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Department of Commerce

FINAL REPORT

DEVELOPMENT O F IMPROVED CORROSAON RESISTANT STAINLESS S T E E L

PROJECT 9 170-4037 CONTRACT DDR- 124

GENERAL ELECTRIC COMPANY, HANFORD

.isrc-- -

W. G. Renshaw

October 23 , 1962

I

Approved by :

R. A . Lula

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

n

A L L E G H E N Y L U D L U M S T E E L C O R P Brac kenr idge, Pennsylvania

FINAL REPORT

DEVELOPMENT OF IMPROVED CORROSION RESISTANT STAINLESS STEEL

O R A T I O N

GENERAL

In t roduc t ion :

PROJECT 917Qd4837 CONTRACT DDR- 124 ELECTRIC COMPANY, HANFORD

The General E l e c t r i c Company, Hanford Works, has encountered d i f f i c u l t i e s with

p re sen t m a t e r i a l s used f o r s t o r a g e tanks and concen t r a to r s f o r r e a c t i v e waste and .- _.__/------- --- -

r e a c t o r v e s s e l s fo2- d i s s o l v i n g fuel. elements. S ince t h e chemical s o l u t i o n s involved --I _-_. ----------- ---

i n t h e process ing must be h igh ly ‘ co r ros ive t o accomplish t h e i r purpose, co r ros ion

problems f o r handl ing equipment, become s e r i o u s a s wel l . I i p such equipment, bu t leaves much t o be d e s i r e d because of h igh co r ros ion r a t e s ; t h e

Type 304L has been employed

problems a s s o c i a t e d with f a i l u r e and d i sposa l of f a i l e d equipment a r e obvious.

is need f o r a l l o y s wi th improved co r ros ion r e s i s t a n c e .

s t e e l have been i n v e s t i g a t e d a t General E l e c t r i c Company and whi le an improvement,

they do no t f u l f i l l a l l t he d e s i r e d c h a r a c t e r i s t i c s needed.

There

Types 309L and 309Cb s t a i n l e s s

The u s e of n i t r i c - h y d r o f l u o r i c mixtures more r e c e n t l y a s a p r e f e r r e d chemical

process ing s o l u t i o n poses a much more s e r i o u s d i f f i c u l t y , because u n l i k e o t h e r

minera l a c i d s , hydro f luo r i c i s not e a s i l y o r r e a d i l y i n h i b i t e d i n i t s co r ros iveness

and n i t r i c provides l i t t l e , i f any, b e n e f i t toward i n h i b i t i o n .

The purpose of t h i s i n v e s t i g a t i o n has been to’develop new o r improved a l l o y s -- - -- e-

which might be employed i n p rocess ing equipment, and e s p e c i a l l y equipment handl ing -.----- ---_--- __L_.- ----___----------- -------

n i t r i c - h y d r o f l u o r i c a c i d mixtures . - -- -__ .--------

Summary:

S p e c i a l modi f ica t ions of Types 309 and 310 and a l s o higher chromium and n i c k e l 2__4- \ --_ - - .- - - ___.--.

E.*

a l l o y s have been eva lua ted f o r t h e i r a b i l i t y to meet co r ros ion requirements . ---- ~

-\

U Tes t s have been conducted on welded and unwelded samples from 15 spec ia l l abora to ry

Page 2

melted compositions i n b o i l i n g 65% n i t r i c a c i d , i n b o i l i n g 13 molar HNO3 wi th add i -

t i o n s of .075M, 0.25M and 0.50M HF, i n 0 . 5 molar s u l f u r i c a c i d , i n 6% f e r r i c c h l o r i d e

and i n a b o i l i n g mixture con ta in ing 6M HNQa + .4M H2SQ4 + .4M NaN03 -‘i- .3M Fe2(S04)3 +

.OLM C r + . O l M Hg + .Om P04. Welds b.ave been examined a f t e r co r ros ion t e s t s , and

s e n s i t i z e d specimens from a l l compositions have been t e s t e d i n b o i l i n g 65% n i t r i c

a c i d .

Success fu l l abo ra to ry me l t ing and process ing of t h e s e compositions t o p l a t e and

s h e e t has been accomplished on smal l s c a l e equipment. Mul t ipass welding by t h e

manual tungs ten i n e r t gas method us ing f i l l e r s t r i p s c u t from s h e e t was s u c c e s s f u l i n

sample p r e p a r a t i o n wi th no evidence of c rack ing or o the r d i f f i c u l t i e s .

It may be concluded t h a t , i n both t h e n i t r i c - h y d r o f l u o r i c mixtures and t h e

tomplex mixture , a much improved gene ra l co r ros ion r e s i s t a n c e over Type 309 can be /-- /-----J

ob ta ined wi th .02% carbon Type 310 Cb, wi th .02% carbon Type_-3JO, and wi th a l l of

t h e h igh chromium n i c k e l a l l o y s . I n regard t o a t t a c k i n weld h e a t a f f e c t e d zones

t h e s e r e s u l t s show t h e .02% carbon Type 310 Cb t o be oqts tanding . While t h e .02%

carbon Type 310 shows some t r a c e evidence of discont inuous p r e c i p i t a t e a t g r a i n

- --. - -- -_ ...-- - -. ---- -.--_ --- . --. . . -- . . ---’ ‘\_____/ - - . - ,

- -~ ....

boundaries , it s u f f e r e d no i n t e r g r a n u l a r a t t a c k ad jacen t t o t h e weld even i n t h e

b o i l i n g n i t r i c - h y d r o f l u o r i c s o l u t i o n s , bu t d i d e x h i b i t a s l i g h t e t ch i n t h i s a r e a . *

The a u s t e n i t i c 30% C r - 25% Ni a l l o y which w a s very e x c e l l e n t i n genera l cor ros ion

r e s i s t a n c e , un fo r tuna te ly s u f f e r e d i n t e r g r a n u l a r a t t a c k i n t h e h e a t a f f e c t e d zone

b u t t h i s may be a t t r i b u t e d t o t h e h igh n i t rogen con ten t ( .084%).

/ __- -

’ \/-~-.u--

F ,

There i s cons ide rab le v a r i a t i o n i n s e n s i t i v i t y of t h e 65% n i t r i c a c i d , t h e

HN03-HF, and t h e complex mixture t o g r a i n boundary p r e c i p i t a t e s o r o t h e r s t r u c t u r a l

cond i t ions . I n t h e course of sample examination i t was d iscovered t h a t t h e complex

s o l u t i o n can cause a u s t e n i t e g r a i n boundary e t ch ing even i n the absence of a v i s i b l e

p r e c i p i t a t e . S i m i l a r l y t h e n i t r i c - h y d r o f l u o r i c s o l u t i o n s s e v e r e l y a t t a c k t h e Type

309 Cb weld s t r u c t u r e but a r e very mild toward Type 310 o r Type 310Cb.

understood about why t h e s e s o l u t i o n s behave a s they do.

Much i s not

Page 3

Recomrnenda t ion :

Based on t h e s p e c i f i c compositions included i n t h i s i n v e s t i g a t i o n , t h e .02%

carbon Type 310 Cb (Heat GD-44) appears most promising as an improvement over Type

309L and Type 309Cb. It possesses improved genera l c o r r o s i o n r e s i s t a n c e i n b o i l i n g

"03-HF s o l u t i o n s and i n t h e b o i l i n g complex mixture and, fur thermore, shows no i n t e r -

g ranular s u s c e p t i b i l i t y o r a c c e l e r a t e d a t t a c k i n h e a t a f f e c t e d weld zones nor does t h e

weld s u f f e r s eve re d i s i n t e g r a t i o n i n e i t h e r s o l u t i o n . A second a l l o y posses s ing

nea r ly a s good p r o p e r t i e s (Heat FV-19A) is a .02% carbon Type 310. On a l abora to ry

s c a l e i t has a l s o been demonstrated t h a t t h e s e Type 310 compositions can be success-

f u l l y mel ted and processed t o p l a t e and s h e e t , and welded wi th no cracking.. Provided

t h e improvements i n co r ros ion r e s i s t a n c e a r e a t t r a c t i v e t o General E l e c t r i c Company,

Hanford, t h e second phase c o n s i s t i n g of t h e development of product ion methods f o r m i l l

s i z e d h e a t s i n s h e e t , p l a t e and tub ing should be undertaken.

Should even a g r e a t e r improvement i n co r ros ion r e s i s t a n c e be d e s i r e d t h e h ighe r

chromium and n i c k e l a l l o y s warrant a d d i t i o n a l i n v e s t i g a t i o n . S ince each of t h e four

d i f f e r e n t C r - N i compositions were r e s t r i c t e d t o a s p e c i f i c carbon and n i t r o g e n con-

t e n t , a program t o s tudy t h e in f luence of t h e s e l a t t e r two elements would be necessary

be fo re they could be recommended. The f u l l y a u s t e n i t i c Heat FV11, a 30 C r - 25 N i

a l l o y , would have deserved recommendation were it not f o r i t s s u s c e p t i b i l i t y t o i n t e r -

g ranular co r ros ion .

Add i t iona l s tudy of t h e p e c u l i a r e f f e c t s of s e n s i t i z i n g on c o r r o s i o n by t h e

HN03-HF and complex s o l u t i o n is ind ica t ed . The unusual a u s t e n i t e g r a i n boundary e t c h

by t h e complex s o l u t i o n even i n the' absence of v i s i b l e p r e c i p i t a t e d ca rb ides i s

unexplained, and equa l ly myster ious i s t h e s l i g h t a c c e l e r a t i o n of HNO3-HF a t t a c k a t

a r e a s where only a t r a c e discont inuous g r a i n boundary p r e c i p i t a t e is p r e s e n t .

A 1 loy Compos i t ion S e l e c t ion :

I n a development program of t h e type involved h e r e i t was necessary t o cons ider / \

s e r i o u s l y t h e problem of i n t e r g r a n u l a r s u s c e p t i b i l i t y i n t h e a s welded c o n d i t i o n s i n c e

Page 4

t h e na tu re and s i z e of t h e equipment involved does not permit a pos t -annea l ing opera-

t i o n . For t h i s reason a l l h e a t s were melted with t h i s i n mind and low carbon o r

columbium s t a b i l i z a t i o n was employed t o accomplish t h i s . Vacuum mel t ing of ve ry low

carbon v a r i a t i o n s of t h e Type 309 composition below .03% was o f f e r e d a s one s p e c i a l

v a r i a t i o n . The a d d i t i o n of columbium t o low carbon Type 310 was another .

The p u r i t y of m a t e r i a l s was cons idered a s poss ib ly a f f e c t i n g t h e gene ra l co r ro -

s i o n r e s i s t a n c e i n these environments and t h e use of h igh and low s i l i c o n modi.fica-

t i o n s of Type 310 a s we l l a s high and low manganese con ten t i n Type 310 was proposed

a s worthy of i n v e s t i g a t i n g .

F i n a l l y t h e s e l e c t i o n of h igher chromium and n i c k e l a l l o y s above t h e s t anda rd

S t a i n l e s s s t e e l ranges would be expected t o provide . . b e t t e r co r ros ion r e s i s t a n c e

because of t h e i r a l l o y con ten t . These a l l o y s could, t h e r e f o r e , s e r v e a t.wo f o l d

purpose because i t i s gene ra l ly known t h a t p r e c i p i t a t i o n of harmful i n t e r g r a n u l a r

ca rb ides i s f r e q u e n t l y r e t a r d e d apprec iab ly i n a duplex a u s t e n i t i c f e r r i t i c s t r u c -

t u r e .

Table I covers t h e composition aims which were s e l e c t e d t o be melted i n t h e

program. These were 100 pound a i r induct ion and 50 pound vacuum induct ion l abora to ry

h e a t s . The r equ i r ed method of me l t ing i s des igna ted i n t h e t a b l e , s i n c e those

m a t e r i a l s wi th ve ry low carbon n e c e s s i t a t e d vacuum mel t ing .

have to be cons idered as a product ion method i f i t were found t h a t t h e s e compositions

Vacuum mel t ing would

E

had t h e b e s t performance i n t h e co r ros ion tests.

. TABLE &

COMPOS I T I O N OF LABORATORY

AIM

S i z e of Method of

HEATS

U I t e m 11 Heat Melt inp C ---- Mn S i C r N i P S Cb

1 loo# A i r Ind. .03 max .75 .35 35 23 .045 max .03 max - 2 loo# A i r Ind. .03 max .75 .35 30 20 .045 max .03 max - 3 l O O # A i r Ind. .03 max .75 .35 30 25 .045 max .03 max -

---

iJ --.

TABLE I (contd)

S i z e of Method of

pehpcI9c..- em # Heat M e l f i n L A L A L 6 r N i 4 5

6

- 7 8 9 10 11 1 2 13 14

15

loo# 50# 50# 5 O# 50#

loo# loo# loo# .508 50# 5 O# 50#

loo#

A i r Ind. A i r Ind.

A i r Ind.

Air-50# A i r - 5 O V A i r Ind. Vacuum Vacuum Vacuum Vacuum A i r Ind.

( a )

(b )

l O O # A i r Ind .

.03 max

.03 max

.03 max

.03 max

.03 max

.03 max

.03 max

.03 max

.01 max

.005 max

.001 max

.01 max

.05 max

.02 max

.75

.10 1.00 . 75 . 75

.75

.75 1 .50 1.50 1.50 1 .50

.50 1.50

.75

Page 5

p s - -L ..35 30 15 .045 max .35 25 20 .045 max .35 25 20 ,045 max .30 25 20 .045 max

1.00 25 20 .045 max 0 25 20 .045 max

.15 25 20 .045 max

.40 22.25 14.50 - * . 4 0 22.25 14.50 -

.40 22.25 14 .50 -

.40 22.25 14 .50 -

.40 22.25 15.25 -

.40 22.50 14.50 - - 3 5 25 20 -

.03 max

.03 max

. 03 max

.03 max

.03 max

.03 max

.03 max

- - - - - . -

(a') (b)

Pour 50 l b . i ngo t and then add 1% Mn t o remaining 50# p o r t i o n Pour 50 l b . ingot and then add 1% S i t o remaining 50# p o r t i o n

I n r e s p e c t t o s t r u c t u r e , t h e proposed compositions were c l a s s i f - i e d i n t o two

groups: duplex s t r u c t u r e . a u s t e n i t i c - f e r r i t i c h e a t s and f u l l y a u s t e n i t i c h e a t s .

Heat numbers 1, 2 , 3 , and 4 (Table I) show t h e composition of t h e proposed duplex

s t r u c t u r e m a t e r i a l s . The main advantage of t h e s e h e a t s i s t h e i r r e s i s t a n c e t o i n t e r -

g ranular co r ros ion . I n h igh ly a l loyed a u s t e n i t i c s t a in l ' e s s s t e e l s t h e s o l u b i l i t y f o r

carbon decreases , and even hold ing t o .03% max carbon con ten t does not seem to be

s u f f i c i e n t t o i n s u r e good r e s i s t a n c e t o i n t e r g r a n u l a r a t t a c k . While. lower carbon

con ten t below .03% would be h e l p f u l , t h i s r e q u i r e s , s p e c i a l me l t ing procedures which

a r e more expensive and t h e r e is a l s o a l i m i t a t i o n i n t h e s i z e of such h e a t s . I n con-

t r a s t t h e duplex s t r u c t u i e m a t e r i a l s a r e r e s i s t a n t t o i n t e r g r a n u l a r a t t a c k a t " 03%

carbon o r even h igher . These f e r r i t e - a u s t e n i t e compositions have, i n gene ra l , h igher

mechanical p r o p e r t i e s , though t h i s might not be an important f a c t o r i n t h e s e l e c t i o n

of a m a t e r i a l . S ince chromium i s t h e most impoftant element i n c o n f e r r i n g c o r r o s i o n

r e s i s t a n c e i n t h e media involved here , i nc reas ing t h e chromium con ten t thus produced

t h e s e duplex , s t r u c t u r e s . The presence of d e l t a f e r r i t e , per s e , does no t adve r se ly

Page 6

a f f e c t co r ros ion r e s i s t a n c e except i n c a s e s where it might l ead t o t h e formation O f

sigma phase. Sigma phase may b e hazardous t o n i t r i c a c i d co r ros ion r e s i s t a n c e . The

n i c k e l conecjtit of the duplex phase W B I var%ad fn erder t e eetablish its i n f luenee in

t h e s e s t r o n g n i t r i c a c i d s o l u t i o n s , and a l s o t o e s t a b l i s h i f i t can c o n t r o l e m b r i t t l e -

ment i n t h e weld.

The a u s t e n i t i c h e a t s were designed t o i n v e s t i g a t e s e v e r a l co r ros ion problems.

Heat number 5 (Table I) was a 25% chromium, 20% n i c k e l h e a t which was d iv ided

i n t o two 50-pound ingo t s of i d e n t i c a l composition wi th t h e except ion of manganese

which was aimed a t . lo% i n one ingot and 1% i n t h e o t h e r . The o b j e c t of t h i s was t o

i n v e s t i g a t e t h e i n f l u e n c e of manganese i n t h e co r ros ion problems. There a r e no da ta

i n t h e l i t e r a t u r e t o r e v e a l t h e in f luence of manganese a t t h i s l e v e l , and i t i s I g ene ra l ly assumed t h a t i t does not a f f e c t co r ros ion r e s i s t a n c e i n t h i s 1ow.range. We

e a r l i e r e s t a b l i s h e d experimental ly i n our l abora to ry t h a t v a r i a t i o n of manganese

con ten t i n t h i s range had n o t i c e a b l e in f luence on the ox ida t ion p r o p e r t i e s .

ox ida t ion and co r ros ion r e s i s t a n c e a r e no t n e c e s s a r i l y r e l a t e d , ox ida t ion du r ing

annea l ing might i n f luence t h e base meta l ad jacen t t o t h e oxid ized s u r f a c e and was

subsequent ly , f o r t h i s reason, considered necessary t o i n v e s t i g a t e .

W h i l e

Heat numbers 6, 7 , and 8 represented 25% chromium and 20% n i c k e l s t e e l s wi th

va r ious s i l i c o n con ten t s .

composition except s i l i c o n con ten t .

chromium - 20% n i c k e l with 0 and .15% s i l i c o n .

i n t e r e s t s i n c e it i s impossible p r e s e n t l y t o produce a commercial a i r mel ted h e a t

with s i l i c o n con ten t lower than .20%. It has been e s t a b l i s h e d t h a t s i l i c o n has an

in f luence on t h e co r ros ion r e s i s t a n c e of a u s t e n i t i c s t a i n l e s s s t e e l s . This was

r epor t ed by Brown, DeLong and Myers*, as wel l a s by Bur ra t .

Heat number 6 was d iv ided i n t o two ingo t s wi th i d e n t i c a l

Numbers 7 and 8 a r e 50-pound h e a t s of 25%

This information was only of academic

Heat numbers 9 , 10, 11, 1 2 , and 13 were Type 309L i n which t h e carbon con ten t

was decreased from . 03 t o ,001 i n order t o e s t a b l i s h t h e l i m i t of s o l u b i l i t y f o r

carbon and carbon l e v e l necessary t o prevent i n t e r g r a n u l a r co r ros ion .

7kASTM S p e c i a l Technica l Pub l i ca t ion No. 165

Page 7

Heat number 14 was Type 309Cb, included f o r comparison wi th o t h e r m a t e r i a l s and

f o r t h e s tudy of k n i f e - l i n e a t t a c k .

Heat number 15 was s e l e c t e d because based on e x i s t i n g publ i shed informat ion

and gene ra l c o n s i d e r a t i o n of t h e co r ros ion and m e t a l l u r g i c a l problems t h i s was t h e

optimum a n t i c i p a t e d composition.

Melt inP and Actual Compositions At t a ined :

I n gene ra l , wi th a few except ions , i t was p o s s i b l e t o a t t a i n t h e d e s i r e d composi-

t i o n a s shown i n Table 11. The composition des igna ted item 1 2 was cance l l ed , however,

because i t was impossible t o a t t a i n t h e d e s i r e d .001% carbon by vacuum induct ion

mel t ing . Heats FV7l-15 and FV70-15 were remade h e a t s u s ing Gra ina l 7 9 , ( l ) s i n c e t h e

o r i g i n a l h e a t s cracked dur ing hot r o l l i n g . Both t h e s e h e a t s have t h e h ighes t d e l t a I

f e r r i t e s t r u c t u r e . I n t h e c a s e of Heat FV56-15, t h e s i l i c o n con ten t was he ld a s low

a s p o s s i b l e t o .033%, but i n order t o do t h i s t h e raw m a t e r i a l s were of such p u r i t y

t h a t carbon con ten t became unusual ly low, .0039%, cons ide r ing t h e .03% maximum carbon

aim. I n t h e fol lowing h e a t , FV57-15, t h e s i l i c o n con ten t of .28% is somewhat h igher

t han t h e aim of .15%. The f a c t t h a t i t l i e s between 0 and the usua l - 4 % average

poin ted t o our dec i s ion t o t e s t t h i s anyhow, s i n c e i t could f i l l t h e gap and main ta in

a reasonable carbon con ten t .

(1)

p r o p e r t i e s : Improves ho t working c h a r a c t e r i s t i c s of wrought s t a i n l e s s s t e e l s and

reduces hea t checking of c a s t i n g s . .The c h i e f advantage of t h e use of Gra ina l 79

i n our work h e r e has been t o avoid c rack ing of t hese h igh a l l o y con ten t s t a i n l e s s

s t e e l s dur ing h o t r o l l i n g . Gra ina l 79 i s manufactured by Vanadium Corpora t ion of

America and has t h e fol lowing chemical composition:

Gra ina l 79 i s an a d d i t i o n f o r f e r rous me l t s which can impart the fo l lowing

c u - B - - C - Mn - Z r - S i A 1 T i

. 1 7 7 . 6 7 . 2 . 8 7 3.24 12.49 21.67 .50 .22

n

n mJ ]! TABLE I1 --

- ACTUAL COMPOSITIONS

Method of Item # Heat No, Melt ing C Mn S i C r N i P - Cb T i Cu Co A 1 N

*1

2

3

*4

5

6

7

8

9

10

11

FV71-15 A i r Ind. .030 .86 .39 34.74 19.70 .024 .017 - .025 .070 .028 - 004 2 -066

N20-15 A i r Ind. .022 . 8 7 .51 30.28 19.83 .008 .010 - .018 .040 .044 -0031 -060

FV11-A A i r Ind. .030 .83 .56 30.32 24.48 .015 .011 - .011 .050 .056 .0017 .084

FV70-15 A i r Ind . ,024 .75 .42

FV17-15A A i r Ind. .017 .33 .52 FV17-15B A i r Ind. .018 1.24 .48

29.96 15.14 .025 .019 - .025 .070 ,053 - 00 30 -037

25.48 20.28 25.36 20.13

.020 .016 - .018 .080 ,058

.015 .016 - .011 .082 .052 .0022 -0026

.048 -046

FV19-15A A i r Ind. -020 .85 .47 FV19-15B A i r Ind. .017 . 8 2 1.07

25.62 20.30 25.18 20 .2 i

.015 .008 - .014 .082 .062

.015 . O M - ,011 .080 .062 .GI013 -0071

.047 -046

FV56-15 A i r Ind. .0039 . 7 7 .033 24.40 19.99 .006 .014 - .014 .030 ,045 -0025 .040

FV57-15 A i r Ind. .021 .90 .28

FY78-14 A i r Ind. .026 1.59 .45

24.80 19.61 .008 ,014 - .011 .030 .069 ,0039 .045

22.25 14.25 .022 -_ ,015 - .014 .035 .039 .0031 .030

RV296-4 Vacuum .-, ,0086 1.51 .42 22.34 14.51 . Q O 8 .010 - .022 .030 .034

.008 .008 - .011 .035 .057

.QO27 -0028

RV294-4 Vacuum .0041 1.57 .46 2 2 . 7 1 14.32 .QQ29 -0044

13

14

15

RV297-4 Vacuum .0081 .59 .45 22.30 15.03 .008 .008 - .014 .030 .031 -0024 .0038

FY79-14 A i r Ind. .043 1.53 .47 22.48 14.25 .015 .013 .40 .014 .042 .034 .0015 .044

. 0 4 3 ' P, 00

03 GD-44 A i r Ind. ,015 .84 .40 24.76 , 20.00 .014 ,015 . 2 2 .014 .057 .035 .0022

q h e s e two hea t s were melted with 4#/ton r a t i o of Grainal 79. O r i g i n a l hea t s cracked seve re ly and had t o be remade.

Page 9

It is s i g n i f i c a n t t o no te t h a t , a l though no aim was made on n i t r o g e n con ten t ,

t h e vacuum melted h e a t s , RV-294, RV296, and RV297, have ve ry low n i t rogen compared

t o t h e usua l normal con ten t of about .04%. On t h e o t h e r hand, t h r e e of t h e v e r y h i g h

C r - N i a l l o y s had s l i g h t l y higher than normal n i t rogen , due t o t h e f a c t t h a t i t i s

added a s a p a r t o f t h e ferrochrome add i t ion . This was of some concern, s i n c e n i t r o -

gen may appear i n a g r a i n boundary n i t r i d e p r e c i p i t a t e s i m i l a r t o c a r b i d e when h igh

n i t rogen s t a i n l e s s s t e e l s a r e s e n s i t i z e d . This i s d iscussed l a t e r i n t h e i n s t a n c e

of Heat FV-11 with .084% N .

Unlike commercial h e a t s , impur i t i e s and n o n m e t a l l i c i nc lus ions a r e more common

i n smal l r e sea rch h e a t s . This f a c t i s o f t e n evidenced a s end g r a i n a t t a c k on heavy

gage co r ros ion t e s t samples; t h i n gage s h e e t i s not . sub jec t t o end g r a i n a t t a c k .

Thus s h e e t samples a r e p r e f e r r e d to e s t a b l i s h co r ros ion ' rates.

Process ing t o Gage :

M a t e r i a l from a l l h e a t s was condi t ioned , forged t o shee t bar and then hot r o l l e d

t o 1/4" p l a t e ( f o r weld t e s t samples). Enough m a t e r i a l was s e l e c t e d a t t h i s s t a g e

f o r t he purpose of provid ing welds, and t h e remaining approximate 40% of each h e a t

was f u r t h e r processed e i t h e r by hot r o l l i n g t o . loo" o r .060" or by hot r o l l i n g t o

. l oo" and subsequent co ld r o l l i n g t o .060".

No d i f f i c u l t i e s were encountered i n process ing any of t h e h e a t s a t any s t a g e s .

The two h e a t s mentioned previous ly , which were remelted u s i n g Gra ina l 79, a l s o pro-

cessed s a t i s f a c t o r i l y wi th no c racking .

f o r a l l h e a t s a r e r epor t ed i n Table 111.

\

i I

The fo rg ing and ho t r o l l i n g temperatures

It i s poin ted out t h a t l abo ra to ry process ing on t h i s smal l s c a l e cannot dup l i -

c a t e commercial ho t f i n i s h i n g p r a c t i c e s .

many times l a r g e r than a l abora to ry ingot , much g r e a t e r r educ t ions a r e necessary t o

S ince t h e s t a r t i n g commercial i ngo t i s

reach t h e gages involved i n t h i s program. Thus g ra in ref inement and uni formi ty of

s t r u c t u r e i n our 1/4" p l a t e tes t samples i s much l e s s than would be a t t a i n e d i n an

Page 10

a c t u a l m i l l product . However, t h e information gained from our p rocess i cg methods i s

h igh ly s i g n i f i c a n t , f o r it i n d i c a t e s t h a t with development of s u i t a b l e m i l l p rocess ing

procedures a l l of the e e m p e s i t i o ~ s a r e probably capable of s a t i s f a c t o r y product ion on

a l a r g e s c a l e .

TABLE 111

PROCESSING DATA

--

Forged t o Sheet Hot Rolled t o Hot Rol led to Cold Rolled t o - Item # Heat No. Bar a t .25" a t * Gage Temp.

1 2 3 4 5

I

6

7 . 8 . 9 10 11 13 14 15

F v 7 1 Fi20 W l l FV 70 FV 17 - 15A E'V 17 - 15B FV19-15A FV 19 - 1 5B FV56 Fv57 FY78 RV296 RV294 RV29 7 FY79 GD44

2200°F 2200°F 2200°F 2200°F 2200°F 2200°F

2200°F 2200°F 2200°F 2200°F 2200°F 2200°F 2200°F 2200°F 2200°F 2200°F

2100°F 2103°F 2100°F 2100°F 2100°F 2,100"F ,

2100°F 2100°F 2100°F 2100°F 2150°F 2150°F 2150°F 2150°F 2150°F 2100°F

.060" 2100°F

.0601' 2100°F

.060" 2100°F ,

,060" 2100°F .060" 2100'F

used f o r . weld f i l l e r .060" 2100°F .060" 2100°F - - - - . loo" 2150°F . 100" 2150°F . l oo" 2150°F ,100" 2150°F . loo" 2150°F . loo" 2100°F

* M a t e r i a l taken a t t h i s gage subsequent ly was annealed a t 2050°F and used f o r weld t e s t s . Samples t e s t e d as welded only, except f o r a few s p e c i a l samples reannealed and then s e n s i t i z e d a t 1200°F.

Annealing and Descalinq:

The p l a t e m a t e r i a l a t 1/4" rece ived an a n n e a l p a t 2050°F f o r 20 minutes , a i r

cooled, followed by desca l ing i n 15% "03 + 3% HF.solu t ion .

quen t ly welded and co r ros ion t e s t e d i n t h e as welded condi t ion .

This m a t e r i a l was aubse-

The p o r t i o n s of each hea t t h a t were hot r o l l e d t o l i g h t e r gages were desca led i n

15% "03 + 3% HF a t var ious s t a g e s and b e f o r e co ld r o l l i n g .

m a t e r i a l s were degreased i n 10% a l k a l i n e c l e a n e r of t h e sodium o r t h o s i l i c a t e t ype and

then annealed a t t h r e e temperatures (2050"F, 2150°F and 2300°F) s i n c e it was f e l t t h a t

annea l ing temperature might have an in f luence on co r ros ion . r a t e s , e s p e c i a l l y where

A f t e r c o l d r o l l i n g all

Page 11

duplex a u s t e n i t i c - f e r r i t i c s t r u c t u r e s a r e p re sen t i n t h e base m a t e r i a l . This informa-

t i o n would a l s o be inva luab le f o r subsequent m i l l processirig a s s i s t a n c e . A l l .060"

s h e e t m a t e r i a l s r ece ived an annea l of 15 minutes , a i r cool , followed by p i c k l i n g i n

15% "03 - 3% HF at 140'F t o d e s c a l e them i n p repa ra t ion f o r c o r r o s i o n t e s t s .

S t r i p s .060" x 3/16" were sheared from Heats FV17B, GD44, N78, RV294, RV296,

RV297, and FY79 f o r f i l l e r meta l i n welding.

We ld inq :

The 1/4" p l a t e s e c t i o n s which were annealed a t 2050'F were c u t i n t o 24" long

s t r i p s and machined t o a s i n g l e V-groove p repa ra t ion wi th a 60' included ang le .

Mul t i -pass welding by t h e manual t ungs t en i n e r t gas method was employed, u s i n g f i l l e r

p e t a l of sheared s t r i p s of s h e e t .

p rovides t y p i c a l s t r u c t u r a l e f f e c t s i n t h e base meta l and weld t h a t would. e x i s t i n

process v e s s e l s and equipment A s u r f a c e c r o s s weld pass was subsequent ly app l i ed t o

Mul t ipass welding which involves h ighe r h e a t input

permit eva lua t ion of t he cond i t ion which would occur i n a c t u a l f a b r i c a t e d s t r u c t u r e s .

F i l l e r meta ls employed i n welding were s t r i p s c u t from s h e e t as fo l lows:

A l l Type 309 compositions were welded wi th f i l l e r s t r i p s c u t from each i n d i v i d u a l ( a )

h e a t .

s i t i o n .

This was a l s o t r u e f o r Heat GD44, t he .02% carbon Type 310 p l u s Cb compo-

( b ) A l l remaining h e a t s used f i l l e r meta l from Heat FV17B, a .02% carbon Type 310.

Table I V shows t h e r e s u l t s of magne-gage readings f o r t h e base m e t a l , a f u s i o n

c r o s s weld, and of t he weld wi th f i l l e r added.

and r e v e a l s a n i n t e r e s t i n g observa t ion t h a t t h e expected duplex s t r u c t u r e f o r Heat

Th i s i s a measure of f e r r i t e con ten t ,

FVll ( a 30 Cr-25 N i hea t ) d i d not m a t e r i a l i z e . Th i s may be due t o t h e f a c t t h i s h e a t

contained .084% ni t rogen , a s t r o n g a u s t e n i t i z e r . The t h r e e vacuum Type 309 h e a t s

with ve ry low carbon and n i t rogen showed some f e r r i t e i n t h e base metal as annealed

a t 2050'F and some i n c r e a s e a f t e r welding.

from t h e f e r r i t e s t andpo in t upon welding. A s expected, t h e high chromium-nickel

a l l o y s show high d e l t a f e r r i t e con ten t s , i nc reas ing when they a r e f u s i o n welded.

None of t h e 25-20 h e a t s were a f f e c t e d

Heat No.

W71

Fv20

Fvll

FV 70

Fv17A

' W17B

Fv 19A

J?V 19B

FV56

FV57

GD44

m 7 a

RV294

RV296

RV29 7

FY79

-.- TABLE - I V

MAGNE-GAGE READINGS

% MAGNETIC PHASE

Annealed @ 2050°F + Welded

Base Metal Analysis

35-20

30-20

30-25

30-15

25-20 + .33 Mn

25-20 w i t h .018 C

25-20 wi th .020 C

25-20 -k 1 S i

25-20 wi th .03 S i

25-20 wi th .28 S i

25-20 Cb

Type 309L

Type 309-very low C

Type 309-very low C i

Type 309-very low C

Type 309 Cb

Base Metal Fusion Weld

18%

12

0

22

0

0

0

0

0

0

0

1

4

3

2

5%

2 7%

12

0

40

0

0 '

0

0

0

0

0

2

I 7

P

6

3

5%

Page 1 2

FV17B F i l l e r Metal

11%

8

0

18 :

0

0

0

- 0

0

0 (.GD44)

. 7 (RV294)

5 (RV296) ,

3 , (RV29 7)

5% (J379)

. I

Page 13

Afte r welding, a l l samples were mechanical ly abraded with a l e a f gr inder

a b r a s i v e b e l t wheel t o remove s c a l e and oxides , then l i g h t l y p ick led i n a d i l u t e

hydrochlor ic a c i d s o l u t i o n (chosen because i t avoids i n t e r g r a n u l a r a t t a c k ) . The

welds were not ground f l u s h wi th t h e s u r f a c e , and i n s t e a d t h e l i g h t p repa ra t ion

desc r ibed above l e f t t h e normal contour of t he weld untouched. Subsequently t h e s e

samples were sawed t o a rough s i z e and edges machined t o dimensions f o r co r ros ion

t e s t s .

t e s t s o l u t i o n s .

Sample P repa ra t ion :

A 1/4" ho le was d r i l l e d a t one end t o suspend t h e samples intended for b o i l i n g

Examination of samples a f t e r co r ros ion t e s t i n g i s d iscussed l a t e r .

The weld samples were prepared a s descr ibed above and the edges ground wi th 120

g r i t emery p r i o r t o t e s t i n g . These were then thorovghly degreased i n a ho t 10% I

a l k a l i n e s o l u t i o n of t h e sodium o r t h o s i l i c a t e type, r i n s e d with h o t d i lu t , e n i t r i c

then d i s t i l l e d water and d r i e d be fo re weighing.

The unwelded s a m p l e s were c u t t o ' s i z e a f t e r anneal ing, and a 1/4" ho le d r i l l e d

i n one end of t h e 1" x 2" s i z e . Af t e r deburr ing each sample was ground on t h e s u r f a c e

and edges with 120 g r i t emery, degreased and then pass iva ted in warm 20% HNO3 s o l u t i o n

t o c l e a n and p a s s i v a t e them be fo re weighing.

I, I

The s p e c i a l s e n s i t i z e d samples prepared f o r t h e b o i l i n g 65% n i t r i c a c i d t es t

were hea ted 1 hour a t 1200'F and then l i g h t l y ground and p i ck led i n d i l u t e (20%)

HC1 s o l u t i o n t o remove a l l oxide scale b e f o r e weighing and t e s t i n g .

The s tandard s i z e samples f o r each environment a r e shown below:

(b) HN03-HF s o l u t i o n - 1" x 2" with 1/4 h o l e a t one end

( c ) Complex mixture - 1" x 2" with 1/4 h o l e a t one end

( d ) 65% "03 - 1" x 2" with 1/4 h o l e a t one'end

( e ) .5M H2S04 - 2" 211

( f ) 6% FeCl3 - 4" x 4"

Page 14

Corrosion T e s t s :

(a)

Xn meat; G Q X ~ O ~ ~ O ~ t e o t preglrams fer new &;bloyo, eelectief\ of prapar and rapre-

General Nature of Corros ion Tes t Environments

s e n t a t i v e s o l u t i o n s is o f t e n very d i f f i c u l t . However, i n t h i s program, we were bene-

f i t t e d by previous experience and knowledge of c e r t a i n process s o l u t i o n s t h a t could

be adapted d i r e c t l y t o t h e program. Two of t h e s e s o l u t i o n s a r e descr ibed i n (b ) and

( c ) below. The t h r e e a d d i t i o n a l s o l u t i o n s ( d ) , ( e ) and (f), a r e commonly used t o

e s t a b l i s h gene ra l knowledge of c o r r o s i o n p r o p e r t i e s of t h e s t a i n l e s s s t e e l s .

(b) 1 3 M "03 + .075M HF a t b o i l i n g 1 3 M H N O 3 + .25M HF a t b o i l i n g 1 3 M HNO? + . 50M HF a t b o i l i n g

N i t r i c a c i d cannot i n h i b i t HF except t o a minor e x t e n t . The r a t i o of "0.3 t o HF l is 4 0 : l on a molar b a s i s , bu t should r ep resen t very seve re cond i t ions where a l l o y

composition can be s i g n i f i c a n t .

l a r a t t a c k e s p e c i a l l y we l l i f t h e s e s u s c e p t i b l e cond i t ions e x i s t i n t h e me ta l .

This s o l u t i o n can develop k n i f e - l i n e and in t e rg ranu-

Increased chromium and n i c k e l o f f e r some advantage t o r e s i s t a t t a c k of t h e meta l

( f u l l y annealed o r i n t h e absence of p r e c i p i t a t e d c a r b i d e s ) .

o f t e n be expected i n t h i s environment.

End g r a i n a t t a c k may

These t e s t s must be conducted i n s p e c i a l equipment because of t h e HF con ten t .

F igure I is a photograph af t h e t es t equipment. A polye thylene r e f l u x tube surrounded

by a g l a s s j a c k e t was i n s e r t e d i n t h e top of t h e Kel-F b o t t l e . Cool ing water was

c i r c u l a t e d through t h e j a c k e t . The samples were suspended by means of knot ted Tef lon

t a p e . The v e s s e l was hea ted t o b o i l i n g by immersion i n a h o t o i l ba th . Ke l -F ,vesse l s

were used i n t h i s case .

t u r e .

Length of the t e s t was s i x 24 hour per iods a t b o i l i n g tempera-

Specimens 1" x 2" of unwelded material were employed f o r weight loss determina-

t i o n s a f t e r va r ious hea t t rea tments a t 2050, 2150 and 2300°F.

examined v i s u a l l y and microscopica l ly a f t e r t h e t e s t t o determine ex ten t of i n t e rg ranu-

lar co r ros ion .

c r o s s s e c t i o n .

Welded samples a r e

Samples were stopped be fo re s i x per iods i f co r ros ion a t t a c k pene t r a t ed

- .- - -- - _- -- .

P

i

qJ

-D ..-

la

0 i !

F i l m G920 A p p r o x . 1/2 Size

FIGURE 1

Kel-F Vessel and Polyethylene Ref lux Condenser Used for Boiling Tests in 1% HNO3 + .075, 0.25 and 0.50 M HF

Page 15

. ( c ) 6M "03 + . 4 M H2S04 + . 4 M NaN03 + . 3 M Fe2(S04)3 + . 0 1 M CrS6 + . O l M Hg + .Om PO4 a t b o i l i n g (108OC) - Complex So lu t ion

Although t h e r e a r e o t h e r a c i d s and s a l t s added, t h i s is p r i m a r i l y s t i l l a s t r o n g

ox id iz ing environment because of t 'he high ( 6 M ) n i t r i c a c i d con ten t . The s u l f u r i c

a c i d is approximately 4% by weight, bu t f o r t u n a t e l y i t s e f f e c t i s n u l l i f i e d b;y t h e

s t r o n g i n h i b i t i n g a c t i o n of both t h e n i t r i c a c i d and f e r r i c s u l f a t e . S i m i l a r l y ,

phosphate ion w i l l have no c o r r o s i v e e f f e c t under such s t r o n g l y ox id iz ing cond i t ions .

Sodium n i t r a t e per s e does not cause o r i n h i b i t co r ros ion t o s t a i n l e s s s t e e l s . , While

t h e in f luence of mercury has never been def ined , i t i s d e f i n i t e l y known th'at hexavalent

C r ion i s s t r o n g l y a c c e l e r a t i n g t o n i t r i c a c i d a t t a c k e s p e c i a l l y i n t h e range named

(.01M).

It i s concluded t h a t t h i s test: i s p r i m a r i l y a b o i l i n g 6M n i t r i c a c i d tes t . s t r o n g l y

a f f e c t e d by t h e a c c e l e r a t i n g Cr+6 ion .

chromium con ten t i s a b e n e f i c i a l c o n s t i t u e n t .

For a l l o y s t o r e s i s t t h i s environment, h igher

The t e s t s were conducted i n co ld f i n g e r r e f l u x condensers a t b o i l i n g tempera-

t u r e . Time pe r iod f o r t h i s t e s t was 240 hours , wi th specimens weighed and l o s s e s

c a l c u l a t e d ( inches p e n e t r a t i o n p e r month) each 24 hours . This i s d e s i r a b l e s i n c e

t h e a c c e l e r a t i n g e f f e c t of accumulating chromium Cr+6 ion can be s tud ied .

remembered t h a t t h e r a t i o of s o l u t i o n volume t o specimen a r e a (approximately 150

It must be

m l / s q inch) i n our t es t would no t exis t i n a c t u a l 'equipment i n s e r v i c e , e s p e c i a l l y

never i n h e a t exchanger tubes .

Weld samples were examined v i s u a l l y and mic roscop ica l ly a f t e r tes ts f o r ev i -

dence of i n t e r g r a n u l a r or o t h e r l o c a l i z e d a t t a c k .

(d ) B o i l i n g 65% N i t r i c Acid

Nitr ic a c i d is s t r o n g l y ox id iz ing , so much so t h a t i t does not even a t t a c k

mild s t e e l a t low temperatures . A t b o i l i n g , 18-8 s t a i n l e s s s t e e l may show c o r r o s i o n

r a t e s of perhaps .7 t o 1 mil/month, while Type 309 Cb shows about . 3 t o . 5 mils/month.

Page 16

Higher chromium con ten t o f f e r s t h e most b e n e f i t t o improve co r ros ion r e s i s t a n c e

whi le f r i n g e advantages of low s i l i c o n , low manganese and low carbon i n t h i s environ-

ment a r e l e s s known.

The t e s t o f f e r s some va lue because it r e p r e s e n t s s t r o n g n i t r i c cond i t ions a s i n

t h e a p p l i c a t i o n , and a l s o because i t is a s t anda rd we l l recognized t e s t f o r s t a i n l e s s

s t e e l s .

Th i s t e s t w a s conducted under r e f l u x cond i t ions with co ld f i n g e r condensers f o r

f i v e 48-hour per iods i n b o i l i n g a c i d . A l l samples were p rebo i l ed 3 hours and weighed

be fo re r e g u l a r t e s t s were s t a r t e d .

r a t e s were c a l c u l a t e d i n inches p e n e t r a t i o n per month. Welded specimens were examined

, for k n i f e - l i n e and i n t e r g r a n u l a r co r ros ion .

t h r e e annealed cond i t ions and a l s o a f t e r s e n s i t i z i n g 1 hour a t 1200°F.

New a c i d was used f o r each per iod . Co'rrosion

Unwelded samples were t e s t e d i n t h e

. ( e ) P i t t i n g T e s t - 6% F e r r i c Chlor ide

The informat ion provided i s o f t e n h e l p f u l s i n c e t h e presence of c h l o r i d e ion a s

a contaminant i n processes can cause hazardous r a p i d p e n e t r a t i o n of v e s s e l wa l l s by

p inho le p i t t i n g . Higher n i c k e l con ten t s a r e known t o be h e l p f u l .

This t e s t r e p r e s e n t s p i t t i n g under s t r o n g l y depo la r i z ing cond i t ions . Specimens

were t o t a l l y immersed a t room temperature and examined p e r i o d i c a l l y for evidence of

p i t t i n g . Freedom from p i t s a f t e r 300 hours i n d i c a t e s a high degree of c o r r o s i o n

r e s i s t a n c e t o l o c a l i z e d a t t a c k by halogens. No weight l o s s e s were c a l c u l a t e d f o r

p i t t i n g t e s t s . ( f ) 0.5M S u l f u r i c Acid a t 200°F

No p resen t s t a i n l e s s s t e e l s w i l l r e s i s t t h i s s o l u t i o n . I n t h e absence of n i t r i c

a c i d or f e r r i c s u l f a t e as i n h i b i t o r s , a t t a c k due t o . 5 M s u l f u r i c is severe . I t . p re -

s e n t s some i n d i c a t i o n of t h e s t a b i l i . t y of t h e pas s ive cond i t ion of t h e a l l o y s involved

i n t h e program.

The t e s t s were conducted f o r 2 hours a t t h e s p e c i f i e d concen t r a t ion and tempera-

The t e s t s were maintained a t 200'F 2 1°F i n a cons t an t temperature water ba th . t u r e .

Page 1 7

r-

..-

I

-L I-

-- u ...

0

Act iya t ion i n 150'F d i l u t e 10% H C 1 was employed p r i o r t o t e s t i n g i n s u l f u r i c a c i d .

Specimens were immersed u n t i l t h e development of hydrogen bubbles on t h e su r face ,

r i n s e d i n ho t water and immediately placed i n t h e s u l f u r i c a c i d s o l u t i o n .

Resu l t s of Corrosion T e s t s :

The t a b l e s p re sen t ing r e s u l t s of co r ros ion t e s t s on shee t m a t e r i a l a r e shown

i n t h e i r e n t i r e t y a t t h e end of t h e r e p o r t i n t a b l e s p re f ixed A, f i g u r e s p re f ixed C .

Tables d e a l i n g with welded samples a r e p re f ixed B i n t h e same manner.

For purposes of d i scuss ion , va r ious p e r t i n e n t summaries w i l l be used i n t h e

t e x t t o i l l u s t r a t e and compare r e s u l t s .

General Corrosion Res is tance of Various Compositions :

A . E f f e c t of Annealing Temperature on Sheet . I

I n t h e development of new a l l o y s some knowledge of proper a n n e a l i n g . temperature

f o r b e s t c o r r o s i o n p r o p e r t i e s i s needed. Previous experience wi th unbalanced, low

n i c k e l Type 316, f o r example, i nd ica t ed t h a t annea l ing a t 2050°F was too h igh and

c o r r o s i o n r a t e s i n b o i l i n g n i t r i c a c i d were excess ive because of d e l t a f e r r i t e . An

annea l a t 1800'F c o r r e c t e d t h i s s i t u a t i o n . S imi l a r reasoning a p p l i e s t o t h e duplex

C r - N i a l l o y s and even t h e ve ry low carbon Type 309 wi th smal l amounts of f e r r i t e .

Corrosion r a t e s i n va r ious environments f o r s h e e t samples annealed a t 2050°F, 2150°F,

and 2300°F a r e compared i n Table V .

r e s u l t s f o r o the r comparisons l a t e r .

This t a b l e a l s o provides a very good summary of

$

I n genera l , v a r i a t i o n i n annea l ing temperature from 2050°F t o 2300°F has r e l a -

t i v e l y minor e f f e c t s , while a l l o y composition has a g r e a t e r i n f luence i n envir inments

such a s HN03-=HF, t h e complex mixture and even i n f e r r i c c h l o r i d e . However, t h e r e a r e

D

some s i g n i f i c a n t r e s u l t s which should b e poin ted ou t r ega rd ing annea l ing .

(a ) There seems t o be a s l i g h t gene ra l t r end f o r dec reas ing co r ros ion r a t e s

i n t h e b o i l i n g "03-HF s o l u t i o n s as annea l ing temperature i s r a i s e d from 2050'F t o

2300°F al though i n a few cases t h e r e v e r s e may be t r u e .

.. . . ~ .... .. , ._.__.__.i ".. ~ .. ... _.. - ~. . ... .. . . . _ . . . _ I _ . . . _ _ . . _ . . . I . . . ~ ..... ^ _ ._ __ . ~ . . .,

Page 18

(b) I n a l l bu t two c a s e s , i nc reas ing annea l temperature from 2050'F t o 2150°F

Rather d r a s t i c i nc reases increased c o r r o s i o n r a t e s i n t h e b o i l i n g complex mixture .

were observed with t h e t h r e e very low carbon and n i t rogen vacuum melted h e a t s , RV294,

RV296 and RV297, and t h e s e show excess ive r a t e s of 8.8, 8 .0 and 7.9 mils/month when

annealed a t 2150'F.

and t h i s unusual phenomenon w i l l b e d iscussed l a t e r .

They show seve re i n t e r g r a n u l a r s u r f a c e a t t a c k i n t h i s environment

(c) Annealing temperature has r e l a t i v e l y l i t t l e e f f e c t on b o i l i n g 65% n i t r i c

a c i d c o r r o s i o n r a t e s except aga in on two of t h e vacuum melted h e a t s , RV294 and RV297,

a s we l l as Type 309L and Type 310, a l l of which inc rease i n r a t e wi th i n c r e a s i n g

temperature .

(d) The r a t h e r e r r a t i c na tu re of t h e s u l f u r i c , a c i d c o r r o s i o n a t t a c k does not I

permit any eva lua t ion a s t o whether h ighe r annea l ing temperature is hazardous o r

b e n e f i c i a l , bu t t h e r e a p p e a r s t o be some e f f e c t , vary ing wi th composi t ions.

( e ) Among those few h e a t s s u s c e p t i b l e t o a t t a c k i n f e r r i c c h l o r i d e i t can be

s a i d t h a t vacuum melted compositions become worse wi th a h igher annea l whereas a l l

o t h e r s improve.

( f ) S ince t h e r e may be inc reas ing o r decreas ing co r ros ion r a t e s i n va r ious

s o l u t i o n s t h e cho ice of annea l ing temperature may be b e s t governed by t h e type of

environment. The a t t a c k by each s o l u t i o n is appa ren t ly d i f f e r e n t , depending upon

s t r u c t u r e of t h e a l l o y material involved.

For purposes of t h e l a t e r i n v e s t i g a t i o n , samples annealed a t 2050°F were

employed i n t h e weld t e s t s because, of m a t e r i a l l i m i t a t i o n s . The f a c t s presented

above must l a t e r be r e c a l l e d i n d i scuss ion of weld tests.

. B . E f f e c t of Composition

To avoid confusion and s i m p l i f y p r e s e n t a t i o n of d a t a f o r e a s i e r comparison,

subsequent d i scuss ion of t h e e f f e c t s of composition w i l l r e f e r on ly t o t h e 2050°F

annea l c o n d i t i o n s i n c e it a p p l i e s t o both s h e e t and weldded p l a t e tests.

INFLUENCE OF ANNEALING TEMPERATURE ON AVERAGE CORROSION RATES

SHEET SAMPLES

Heat No.

FV71

F v l l

FV20

FV 70

FV19B

FV 56

FV57

FV17A

FV19A

GD44

RV296

RV294

Type

35 Cr-20 N i

30 Cr-25 N i

30 Cr-20 N i

30 Cr-15 N i .

310 + 1 S i

310 + .03 Si + .004C

310 f .28 S i

310 + .33 Mn

310 + .02 C

310 + Cb

309 + .008 C

309 + .004 C

Annea led a t

2050°F 2 150 2300 2050°F 2 150 2300 2050" F 2 150 2300 2050°F 2 150 2300 2050°F 2 150 2300 2050°F 2 150 2300 2050 OF 2 150 2300 2050 OF 2 150 2300 2050°F 2150 2300 2050°F 2 150 2300 2050" F --- 71 50

2300 2050°F 2 150 2300

13M HNO3 .25M HF

m i 1s /mo

35 30 25 29 26 28 32 34 29 37 34 42 52 47 46 44 49 50 44 42 34 61 75 62 38 43 45 45 44 38 .

57

47 58 70 57

r;? >L

13M "03 .50M HF rnils/mo

37 42

44 39

42

*

* * * 51 48

62 58

7 1 61

75 70

72 98

53

*

*

*

*

* *

a *

64 75 .

93 30

87 89

*

*

*

Complex Mixture mils/mo Avg.

3 . 3 3 .5

3 . 1 2.6

3 .1 3.8

3.8 4 .0

3 . 3 2 .9

2 . 8 3.1

2 . 8 3 .0

3 . 1 3 .2

2.9 3 .4

3 .5 3.8

7 . 8 8 .8

6 . 2 8 .0

*

*

*

*

*

*

*

*

*

* .

*

*

65% "03 in/mo Avg.

.0018

.00020

.0002 1

.00024

.00020

. 000 18

.00020

.00018 . 000 18 -00017 .00023 .00023 .00034 . 0001 7 .00022 .00024 .00024 .00023 .00020 .00023 .00023 .00027 .00026 .00023 . 000 19 ,00031 ,00032 .00024 .00024 .0002 7 .00024 .00028 .00032 .0002 7 .00027 .00028

.5M H2s04 i n h o A V ~ .

-33 - 32 .24 - 2 2 .30 .32 .14 -26 . .25 -42 -023 * 7 1 -20 -10 .28 -16 __ .08 -18 - 23 .30 .23 .LO . 1 7 . I 7 .23 .26 .26 - 2 7 .29 .14 -25 .24 . 2 3 .38 -28 -45

FeC 13 Hours t o P i t

100 100 300 No p i t s No p i t s No p i t s 100 . 100 100 24 24 24

No p i t s No p i t s No p i t s No p i t s

24 100 N o p i t s No p i t s No p i t s No p i t s No p i t s No p i t s No p i t s 2 No p i t s % NO p i t s ~

No p i t s a No p i t s No p i t s 168 144 24

144 144 48

- TABLE V_ ( contd) -

F ~ C 13 1 3 M "03 13M "03

Amealed .25M HF .50M HF Complex Mixture 65% "03 .5H H2SO4 Hours a t mils/mo Avg. in/mo Avg:. injmo Avg. t o P i t Type mils/mo milslmo - Heat No.

59 8 5 4 2 150 55 90

RV29 7 309 -:- .008 C 2050°F ,

FY 78 309 -E .026 C

FY79 309 t- Cb

* Not Tested

2300 2050°F

54 77

_ _ * 105

2 150 54 102 2300 51 * 2050°F 69 126 2 150 60 94 2300 62 *

6.6 7.9

5.7 5.9

5 . 3 5.4

*

*

*

.00023

.00028

.00033

.00022

.00026

.00030

.00028

.00029

.00028

.16

. 2 1

.25

.35

.34

.37 - 2 7 -26 29

168 144 24 56

168 144 N o p i t s No p i t s No p i t s

7

,

h, 0

Page 21

Table V I i s a condensed ve r s ion of r e s u l t s f o r 2050'F.annealed shee t i n t h e

t h r e e HNO3-HF s o l u t i o n s , t h e complex mixture and the b o i l i n g 65% "03 t e s t . S u l f u r i c

a c i d and f e r r i c c h l o r i d e r e s u l t s , which show l i t t l e r e l a t i o n t o t h e o the r tests w i l l

be d iscussed s e p a r a t e l y .

It is immediately apparent upon inspec t ion of t h e t a b l e t h a t t h e r e a r e d r a s t i c

d i f f e r e n c e s i n co r ros ion r a t e s among t h e f i v e d i f f e r e n t s o l u t i o n s , va ry ing a s much

as 300 f o l d between b o i l i n g n i t r i c a c i d and t h e s t r o n g e s t "03-HF mixture . A second

s i g n i f i c a n t observa t ion is t h a t t h e r e i s no r e l a t i o n s h i p among t h e t e s t s , and good

c o r r c s i o n r e s i s t a n c e i n one environment does not permit a p r e d i c t i o n that propor t ion-

a l l y good performance of a n a l l o y can be expected i n one of t h e o t h e r s .

bxcept ion e x i s t s f o r t h e t h r e e "O3-HF s o l u t i o n s which show reasonable good r e l a t i o n -

s h i p to each o the r and r a t e s i nc rease p ropor t iona te ly wi th HF con ten t . For example,

a comparison of t h r e e h e a t s w i l l be shown below t o i l l u s t r a t e t h i s b e t t e r . A l l have

p r a c t i c a l l y t h e same n i t r i c a c i d co r ros ion r a t e s bu t v a s t l y d i f f e r e n t behavior i n

o t h e r environments.

Heat No. Type B o i l i n g 65% H N O l Complex Mixture 13M " 0 2 4 .5OM HF

A s l i g h t

Fv 11 30 Cr-25 N i .00024 in/mo 3 . 1 mils/mo 44 mils/mo GD44 310 Cb .00024 in/mo 3 . 5 mils/mo 64 mils/mo Fy79 309L .OOOZZ in/mo 5 .7 mils/mo 105 mils/mo

It is necessary, t h e r e f o r e , t o eva lua te a l l t h r e e type environments a t t h e same

t ime t o have any s i g n i f i c a n c e . Ind iv idua l d i scuss ion of d i f f e r e n t compositions o r

groups of compositions w i l l fo l low.

( a ) g i g h Chromium Nickel Alloys

Taking f i r s t t h e four h igh chromium n i c k e l a l l o y s , t h e s e show d e f i n i t e l y t h e

lowest c o r r o s i o n r a t e s i n t h e JmO3-HF s o l u t i o n s of a l l t h e m a t e r i a l s t e s t e d . They do

no t , however, show any d i f f e r e n t co r ros ion r a t e s t han Type 310 o r i t s mod i f i ca t ions i n

t h e complex mixtures and, i n f a c t , may even show s l i g h t l y g r e a t e r a t t a c k .

t h e i r performance i n n i t r i c a c i d i s about t h e same a s t h e o the r m a t e r i a l s i n t h e pro-

gram though perhaps a l i t t l e lower than t h e Type 309 group. Comparing' w i th Type 310

Furthermore,

Heat NO.

Fv.7 1

F v l l

I Fv20

Fv 70

FV 19B

FV56

Fv57

E'V 1 7 A

FV 19A

GD44

RV296

RV294

RV29 7

FY78

FY 79

Page 22

TA%LE UI

EFFECT OF COXPOSITJON ON CORROSION RATES

SHEET SAMPLES ANNEALED 2050°F

13M "03 f 13M "03 + 13M "03 + .075M HF .25M HF .50M HF Complex Mix 65% FINO3

Type mils/rno miIs/mo m i Is /mo mils/mo inlmo

35 Cr-20 N i

30 Cr-25 N i

30 Cr-20 N i

30 Cr-15 N i

310 -k 1.0 S i

310 + .03 S i *

310 + .28 S i

310 + . 33 Mn

310 + .020 c

310 + C b

309 + .008 C

309 + .004 C

309 + .008 C

309 + .026 C

309 + Cb

-:: . 004% c

11.3

10

1 1 . 3

17.6

16.8

17 .5

14 .5

22.3

15

13

20

19 .2

19

25.8

22.5

35

28

32

36.4

52

44

44

6 1

39

4 5 . 5

57

57 .5

58 .5

' 76.5

69

37

44

"42

51

62

73

73

72.5

73

64

93

8 7

82

105

126

L

3 . 3

3 . 1

3 . 1

3 . 8

3 . 3 .

2 . 8

2 .8

3 . 1

2 . 9

3 . 5

7 . 8

6.2

7.6

5 .7

5 . 3

. 000 18

.00024

.00019

* .00017

.00034

.00024

.00020

,0002 7

.00019

.00024

.000%4

.00027

.00023

.00022

.00028

, - ~ . .. .. . ~~ ~ . _..~ ~ , ~ . .. . . . ... .. - . . I..___.-. .~ .. ...... , - . . . . , . . .. . . , -. . . . . , . . . . -.. __ .. .. . . .

Page 23

m a t e r i a l s i n t h e HN03-HF s o l u t i o n s , t h e r e i s i n d i c a t i o n t h a t i nc reas ing chromium

con ten t t o 30% i n Heat FV20 and t o 35% i n Heat FV71 with a 20% n i c k e l l e v e l has

provided added c o r r o s i o n r e s i s t a n c e .

30% C r and 15% N i wi th t h e Type 309 s t e e l s shows even more d r a s t i c improvement f o r

an inc rease of 8% chromium con ten t . A l l of t h e s e four s p e c i a l chromium n i c k e l a l l o y s

a r e a cons ide rab le improvement over Type 309 m a t e r i a l s i n t h e complex mixture . The

e f f e c t of n i c k e l i s l e s s pronounced than chromium, a t l e a s t a t t h e h igher chromium

l e v e l s , and a change of 10% n i c k e l does not a f f e c t r a t e s t o any g r e a t e x t e n t .

S i m i l a r l y a comparison of Heat FV70 con ta in ing

The f u l l y a u s t e n i t i c 25 Cr-20 N i Heat FVll appears promising i n t h i s group,

showing good c o r r o s i o n r e s i s t a n c e and o f f e r i n g c e r t a i n advantages of a s i n g l e phase

] s t r u c t u r e .

(b) Type 310 Group

A s a whole, t h i s group o f f e r s a marked improvement over t h e Type 309 s e r i e s in

t h e complex mixture s o l u t i o n and HN03-HF s o l u t i o n s . There is v a r i a t i o n i n t h i s group,

s i n c e s e v e r a l composition f a c t o r s were inves t iga t ed .

Heat FV19B showed i n t e r e s t i n g good performance i n t h e HN03-HF s o l u t i o n s , bu t d id

appear s l i g h t l y i n f e r i o r t o a l l o the r h e a t s i n b o i l i n g 65% n i t r i c a c i d . No outs tand-

ing c o r r o s i o n r e s i s t a n c e w a s r e a l i z e d w i t h t h e very l o w s i l i c o n (and ve ry low .004%

carbon) Heat FV56 o r with t h e low .33% manganese Heat FVl ' IA, which may a c t u a l l y

The ve ry h igh s i l i c o n con ten t

be somewhat i n f e r i o r i n HNO3-HF s o l u t i o n s . From t h e more p r a c t i c a l s t andpo in t e i t h e r

a .02% carbon Type 310 o r a .O2% carbon Type 310 Cb, Heats FV19A and GD44 r e s p e c t i v e l y ,

appear promising i n t h i s group. These l a t t e r two show s u p e r i o r i t y t o Types 309L and

309 Cb i n bo th HN03-HF and complex s o l u t i o n t e s t s .

( c ) Type 309 Group

In t h i s s e r i e s t h e most paradoxica l behavior i s exh ib i t ed . Somewhat b e t t e r

c o r r o s i o n r a t e s of t h e t h r e e ve ry low carbon vacuum melted h e a t s over 309L and 309 Cb

i n HNO3-HF s o l u t i o n s i s n u l l i f i e d by t h e i r poorer r e s i s t a n c e t o t h e complex s o l u t i o n .

Page 24,

Regardless , however, t h e group a s an e n t i r e t y i s poorer than a l l o the r m a t e r i a l s

included i n t h e program. Very low carbon and n i t r o g e n con ten t of t h e vacuum melted

Type 309 h e a t s does appear a b e n e f i t i n HN03-HF.

A s a consequence of t h e comparison above, c e r t a i n conclus ions can be reached

regard ing t h e p r e f e r r e d compositions f o r b e s t co r ros ion r e s i s t a n c e .

Using t h e r egu la r Type 309L (Heat F Y 7 8 ) and Type 309 Cb (Heat F Y 7 9 ) a s a base

f o r comparison it i s q u i t e ev ident t h a t Type 310L ( a c t u a l l y .020 C i n Heat FV19A)

and Type 310 Cb (Heat CD44) o f f e r much supe r io r r e s i s t a n c e t o both t h e HN03-HF

s o l u t i o n s a s wel l a s t h e complex mixture . R e l a t i v e l y l i t t l e s i g n i f i c a n c e of compo-

s i t i o n is noted i n t h e 65% b o i l i n g n i t r i c a c i d t e s t s . Apparent ly t h e 65% b o i l i n g

i n i t r i c t e s t i s most u s e f u l f o r eva lua t ion of sensi i5izat ion and i n t e r g r a n u l a r

s u s c e p t i b i l i t y ; more of t h i s w i l l b e d iscussed l a t e r .

I n a d d i t i o n f o r t h e u l t i m a t e i n co r ros ion r e s i s t a n c e t o t h e "03-HF s o l u t i o n s ,

i t i s apparent t h a t t h e h igher chromium and n i c k e l a l l o y s o f f e r t h e . g r e a t e s t b e n e f i t .

Among t h e s e h e a t s , FV11, a 30 Cr-25 N i a l l o y which is f u l l y a u s t e n i t i c i n s t r u c t u r e ,

shows t h e b e s t c o r r o s i o n r e s i s t a n c e . None of t he h igh C r - N i a l l o y s , however, o f f e r

any b e t t e r co r ros ion p r o p e r t i e s than t h e Type 310 a l l o y s i n t h e complex mixture o r

in boiling 65% "03. Both Type 310 and t h e high C r - N i a l l o y s a r e , however, much

b e t t e r than any of t h e Type 309 all .oys i n t h e complex mixture .

F igure 2 i s a b a r graph which compares performance of .026% carbon Type 309;

Type 309 Cb; .020% carbon Type 310; Type 310 Cb; and 30% Cr-25% N i a l l o y i n t h e

13 Molar HNO3 + .25 Molar HF and i'n t h e complex mixture . It i s evident t h a t a n

improvement i n co r ros ion r e s i s t a n c e has been obtained.

C . S u l f u r i c Acid and F e r r i c Chlor ide P i t t i n g T e s t s

The r e s u l t s of both these t e s t s have no r e l a t i o n s h i p t o t h e o the r environments

and w i l l be d iscussed s e p a r a t e l y he re .

There i s no r e l a t i o n s h i p observed between s u l f u r i c a c i d co r ros ion r a t e s and

any composition p r imar i ly because co r ros ion i n s u l f u r i c a c i d under t h e s e t e s t

.: ..._ i _ _ _ j ,... .. , . ," _. ._ . ._ . - . . . . ._ -. . . . . . . . . ~.

c-

U

mil

s/m

onth

-_ -Q

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+ X

09

w

P

VI

a\

w

0)

a

0

0

0

0

0

I I

Y I

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w

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I I

1 0

0

0

0

0 F

v-11

30

Cr

- 25

Ni

mi 1s /

mon

th

I I

0

P

Iu

W

CI

cn

m

v

I I

I I

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. . .

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~ . ... . . .

... . . . -

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.

Page 251

cond i t ions is t ak ing p l ace i n t h e a c t i v e s t a t e , and r a t e s a r e known t o b e e r r a t i c i n

such cases . It was hoped t h a t some higher a l l o y ~ 0 1 n p ~ s i f i 0 n 6 might show p n o s i v i b y

i n t h i s t e s t . Some i n t e r e s t i n g information was learned from t h e s e t e s t s on welded

p l a t e samples. These a r e summarized i n t h e fo l lowing s h o r t t a b l e , cover ing v i s u a l

examination of t h e machined edges f o r unusual a t t a c k . End g r a i n a t t a c k , a form of

very deep l i n e s of co r ros ion a t t a c k usua l ly a s s o c i a t e d wi th t h e presence of non-

m e t a l l i c i nc lus ions

Heat No.

FV 70

I Fv71

Fv 20

F v l l

FV17A

FV 19A

Fv 19B

FV 56

FY78

R V 2 9 6

R V 2 9 4

R V 2 9 7

M79

Heats FV70 and

was observed on some m a t e r i a l s :

Descr ip t ion of S u l f u r i c Acid Test (Welded) Specimens

Heavy end g r a i n a t t a c k . Heavier band of e t ch ing . s t a r t i n g a t weld and extending out about 3/16" i n t o base meta l .

Same a s FV70

L igh t e t ch

Light e t c h

Appreciable end g r a i n a t t a c k

Light e t c h only

Light e t c h only

Trace end g ra in a t t a c k

Severe end g r a i n a t t a c k

Severe end g ra in a t t a c k

Severe end g ra in a t t a c k

Severe end g r a i n a t t a c k

Severe end g r a i n a t t a c k

FV71 con ta in t h e h ighes t amounts of d e l t a f e r r i t e . Apparent ly

the h e a t a f f e c t e d zone s u s c e p t i b l e t o s l i g h t l y more r a p i d s u l f u r i c a t t a c k i n t h e s e

a r e a s is not a c a s e of p r e c i p i t a t e d ca rb ides , but more l i k e l y d e l t a f e r r i t e .

The f e r r i c c h l o r i d e t e s t r e s u l t s a r e a l s o of i n t e r e s t , s i n c e r e s i s t a n c e t o

c h l o r i d e p i t t i n g is va luab le i n chemical process ing equipment. F a i l u r e due t o r a p i d

Page 20

pene t r a t ion of a tank wal l can he hazardous.

p i t t e d m a t e r i a l i s i l l u s t r a t e d by F igure 3 f o r one of t h e welded p l a t e specimens.

The t y p i c a l appearance of a deeply

C e r t a i n m a t e r i a l s showed very good r e s i s t a n c e t o p i t t i n g i n 300 hours exposure.

It i s s i g n i f i c a n t t o no te t h a t t h i s environmer,t was found t o be r a t h e r s e n s i t i v e

t o d e l t a f e r r i t e . Those h e a t s which f a i l e d by p i t t i n g were i n every i n s t a n c e

compositions con ta in ing d e l t a f e r r i t e even i n s m a l l amounts of 2% o r 3%. There i s

no r e l a t i o n s h i p between f e r r i t e con ten t and t ime t o p i t t i n g , however.

E f f e c t of Welding or S e n s i t i z i n g on Corrosion Res is tance :

A . Welding

The r e s u l t s of co r ros ion t e s t s on a s welded samples appear i n Tables B - 1 t o

I B - 5 i n c l u s i v e a t t h e end of t h e r e p o r t . While t h e co r ros ion r a t e s a r e of g r e a t

i n t e r e s t , they a r e inf luenced by c e r t a i n f a c t o r s more c r i t i c a l which demand v i s u a l

o r microscopic in spec t ion , namely end g r a i n a t t a c k , weld a t t a c k o r p i t t i n g and

poss ib ly i n t e r g r a n u l a r a t t a c k .

F igure 4 i s a photograph of s e l e c t e d samples a f t e r tes ts i n t h e b o i l i n g c-omplex

s o l u t i o n of n i t r i c a c i d and s u l f u r i c a c i d p lus c e r t a i n s a l t s . These were c u t f o r

microscopic examination be fo re phot.ographing. I n genera l , t h e ex ten t of a t t a c k i s

much l e s s than i n t h e n i t r i c - h y d r o f l u o r i c s o l u t i o n s shown l a t e r . NO s eve re weld

a t t a c k o r p i t t i n g has occurred. However, c e r t a i n hea t s show f a i n t evidence of

a t t a c k i n h e a t a f f e c t e d zones i n t h i s s o l u t i o n . Although it is somewhat d i f f i c u l t

t o no te from t h e photograph, a l l t h e samples show s l i g h t l y d i f f e r e n t a t t a c k i n t h e

h e a t a f f e c t e d zone than t h e base meta l .

bands of a t t a c k extending out from t h e weld t o about 3/16" o r 1/4".

N 7 9 , FV17A, and FV17B show apparent narrower bands of a t t a c k very c l o s e t o t h e

weld. F V l l shows a broad band of a t t a c k which s ta r t s beyond 1/8" from t h e weld.

A l l o t h e r h e a t s show no a c c e l e r a t e d l o c a l i z e d a t t a c k i n t h i s c o r r o s i v e medium.

Heats RV294, RV296 and RV297 show apparent

Heats FY78,

I n F igure 5 we have shown a l l the weld specimens a f t e r they have been t e s t e d

i n t h e b o i l i n g 13 molar n i t r i c -:- 0.25 molar hydro f luo r i c s o l u t i o n . I n t e r g r a n u l a r

6'y0 F'I:RRIC C I I L O K I D E P I T T I N G TEST

HEAT FV-20

PITTED 20 I-IRS BASE NETAL PITTED 96 IlRS IN VELD

F i l m 6994

FIGURE 3

i-:. , . . I I. .. , CY".. P' . .

. '<.

i ; I \ .~

.. -. .......

FV-17B 3 . 5 m i l s / m o

F V - 1 7 A 3 . 5 m i l s / m o

..... .'.' ...

F Y - 7 8 4.9 rnils/mo

Film G995

, RV-E94 4 . 9 m i l s / m o

RV-297 5 . 2 m i l s / m o

FY-79 4.6 rn l l s /mo

FIGURE 4

r---

. - _. _I - . -

HIGH C R - N I TYPE 310 GROUP TYPE 309 GROUP

FV-71 4 2 m i l s / m o

FV-19B 56 mils/mo

RV-296 82 m i l s / m o

FV-11 45 mils/rno

FV-56 59 m i l s / m o

RV-294 68 ;r i ls/mo

. . . . . . .-..:. .... .... 6,- : ' g ./" .?" .,

' , :I' -. - , -~

I <.- t

6". ...... -. .. ......... ........ I

FV-20 35 m i l s / m o

Fv-57 50 m i l s / m o

RV-297 60 m i l s / m o

-.

- . . . . .~ . . . . . - '7

. . %..ai !

i

FV-17A 7 1 rni ls /mo

FY-78 7 2 mils/mo N - 7 0

54 m i l s / m o

N-19.4 39 m i l s j m o

- - - AS WELDED SAMPLES ' c , 2

- - AFTER S I X - 2 4 HOUR PERIOIJS

I N B O I L I N G 131? HNO3 + .25M HF GD-44

49 m i l s / m o

la .............. .. . . . . . . . . ..-.L.-. -....---,..-.- ..................................... -..-.. .-.. l__.l__ __- ,. .

Film G996

FIGURE 5

............... . ............. .- ----------I--..--.~-.-____I__. _-_______. .. . . . . ..-......; .L :.:z-::.L--zzz,--- ................ ...... ........... ........ . .

Page 2 7

a t t a c k is very evident on Heat FV11, and some apparent s l i g h t a c c e l e r a t e d a t t a c k

ad jacen t t o t h e weld can be f a i n t l y seen on Heats FV193, Fv56, FV71, W19A and

FY78.

t h e Type 309 Cb wi th f i l l e r meta l of t h e same composition.

p i t t i n g of t h e weld and base meta l ad jacen t t o t h e weld on Heat N 1 7 A , a " 3 3 %

manganese Type 310.

It i s a l s o obvious t h a t s eve re weld d e t e r i o r a t i o n has occurred OE Heat FY79,

There was apprec i ab le

The appearance of samples i n the, b o i l i n g 13 molar "03 + .50 molar HF so.Lution

i s s i m i l a r t o t h i s photograph with t h e except ion of more seve re a t t a c k of F V l l and

FY79. Samples FV19B, FV56, FV19A and FY78 l ikewise appear t h e same i n a l 1 , t h r e e

"03-HF s o l u t i o n s , with a f a i n t l i n e of a t t a c k ad jacen t t o t h e weld but which is not

l i n t e rg ranu la r .

l a t t e r samples i n any of t h e t h r e e s o l u t i o n s .

The depth of a t t a c k i s not more than .001" on any of t h e s e four

To b e t t e r r e p o r t t h e r e s u l t s of a t t a c k i n t h e weld and t h e heat. a f f e c t e d zones,

t h e fo l lowing Figure 6 and Table V I 1 have been employed t o he lp d e s c r i b e t h e a r e a s

i n ques t ion . A v i s u a l r a t i n g of t h e i n t e n s i t y of a t t a c k i n both environments i s

given i n

1 -

2 -

3 -

4 -

P -

x - E -

The

s o l u t i o n

Table V I I . Numerical r a t i n g s used a r e descr ibed a s fo l lows:

Neg l ig ib l e a t t a c k wi th r e s p e c t t o ad jacent a r e a s

Slight acce lera ted a t t a c k less t han .004" w i t h r e spec t t o ad jacen t a r e a s

Acce lera ted a t t a c k up t o .020" with r e s p e c t t o ad jacen t a r e a s

Very severe a t t a c k

P i t t i n g

D e f i n i t e i n t e r g r a n u l a r

End g r a i n a t t a c k

average co r ros ion r a t e s f o r a l l t h r e e HN03-HF s o l u t i o n s and t h e complex

a l s o appear i n Table VII.

.... .... .-. . ... .. .. - .. .... ... .. . . . - -. - ..... .. . _.___ .. - . .

c-

a

rl Q

Ja

3

4

a 4

z aJ 3

a

rl a, 3

VI

w

0 k

8 k

l4-I U

0

U

E k

w

a

rl

P 4

rl

a, 3

a

U

rl a, 3

w 0

- N m

E k w

m

u aJ E

4

a'

U

ti" a, w

rb n

a, C 0 N

\

rl

-_

--0 a

.a,

U

U

aJ w

w

rp

a c a,

0" a aJ a a, c

.I4 c U

i!

-0

a, C

.I4

c c)

m

a

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m

aJ c

.-

I

la

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c3. 4

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TABLE V L L

VISUAL RATING OF WELDED SAMPLES APTER CORROSION TESTS I N 13 MOLAR "03 + .SO MOIAR HF

AND LN COMPLEX MIXTURE

Corrosion Rates i n Complex Mixture Surface Welded HNO3 - .50 Molar HF 1 3 ~ "03 + Rate Grain Boundary

Re.?+ No. Type With B, C p E E .07% .25M .50M & C E E mils/mo Etch

W71 35 Cr-20 Ni 310 1 1 1 2 3 2 3 2 26 42 85 1 1 1 1 E l 1 1 1 3.8 No

F v l l 30 Cr-25 Ni 310 1 1 P 1 2 3 x 1 4 x 2 17 45 7 1 1 1 1 1 2 1 2 x 1 3.7 Yes

w 2 0 30 Cr-20 Ni 310 1 1 1 2 2 1 1 1 14 35 76 1 1 1 1 1 1 1 1 3.4 No

Fv 70 30 Cr-15 Ni 310 1 1 1 E . E 1 2 1 25 54 83 1 1 1 1 1 1 1 1 4.6 No

FV19B 310 + 1 Si 310 1 1 3 P 3 E 3 E l 2 1 23 59 94 1 1 1 1 1 1 1 1 3-8 Yes

N 56 310 + .03 Si 310 1 3P 3P 1E 1E 1 2 1 30 59 9 1 1 1 1 1 1 1 1 1 2.8 Yes

Pv57 310 + .28 Si 310 1 2 P 2 P 1 1 1 1 1 27 50 92 1 1 1 1 2x 1 1 1 --2.9 Yes

FV17A 310 + .33 Mn 310 4P 4P 4P 1E 1E 4P 1 1 30 11 115 1 1 1 1 1 1 1 1 3.5 Yes

PI 19A 310 + .020 C 310 3P 3P 4P 2E 2E 1 2 1 22 39 8 7 1 1 1 1 1 1 1 1 3.2 Yes

W17B 310 + .018 C 310 1 1 3 P 1 1 1 1 1 23 59 122 1 1 1 1 1 2 1 1 3.5 Yes

GD44 310 Cb GD44 1 1 2 F 1 1 1 1 1 27 46 92 1 1 1 1 1 1 1 1 3.7 Yes

1 1 1 1 1 2 2 1 5.1 Y e s RV 29 6 309 + .008 C RV296 2 2 2 1 1 1 1 1 36 82 133

1 1 1 1 3 x 2 2 1 4.9 Yes 38 68 149 RV294 309 + .004 C RV294 3 3 3 1 1 1 1 1

RV29 7 309 + .008 C RV297 2 2 ' 2 1 1 1 1 1 34' 70 122 1 1 1 1 3 x 2 2 1 5.2 Trace

pY78 309 + .026 C F178 1 1 1 2 E 2 E l 1 2 38 72. 122 1 1 1 1 1 2 x 1 1 4 . 9 Yes

my79 309 + Cb FY79 4 4 4 1 ' 1 1 1 1 70 118 193 1 1 1 1 3X 3X 1 1 4.6 Yes

Page 28

No d e f i n i t e a c c e l e r a t e d a t t a c k could be observed on any of t h e b o i l i n g 65%

&-u - n i t r i c a c i d weld t e s t specimens, even under 30X magni f ica t ion . The occas iona l

s l i g h t l y higher r a t e s on welded p l a t e was a t t r i b u t e d t o somewhat rougher s u r f a c e s

and s l i g h t t r a c e s of end g r a i n a t t a c k ( o f t e n ccmmon t o l abora to ry s i z e h e a t s ) .

There was no a c c e l e r a t i o n of co r ros ion r a t e s from pe r iod t o per iod , a phenomenon

observed when i n t e r g r a n u l a r a t t a c k occurs . -- However, t o more c a r e f u l l y examine any compositions suspec ted of i n t e r g r a n u l a r

a t t a c k , s h e e t samples of each composition and s p e c i a l s e l e c t e d p l a t e s were reannealed

a t 2050°F and then s e n s i t i z e d f o r one hour a t 1200°F and t e s t e d i n b o i l i n g . 6 5 % n i t r i c

a c i d . Resu l t s of s e n s i t i z e d s h e e t appear i n Table A - 7 and s e n s i t i z e d p l a t e i n Table

9-6 a t end of t h e r e p o r t . I n both cases some inc rease of co r ros ion r a t e was observed,

B .-.- -u -

- n

but s u r p r i s i n g l y t h e s e samples showed no i n t e r g r a n u l a r s u r f a c e a t t a c k nor adid r;hey -u -_ show inc reas ing co r ros ion r a t e s from per iod t o pe r iod , which would tend t o f u r t h e r

- P confirm t h a t no i n t e r g r a n u l a r a t t a c k had occurred.

I f we r e f e r t o t h e f i v e hea t s we compared previous ly i n the ba r graphs i n

F igure 2 a s t h e most promising compositions, and s e l e c t them f o r f u r t h e r s tudy a s

i n Table V I I I , we w i l l no t e a l l have increased r a t e s a s s e n s i t i z e d .

TABLE VI11 -- - EFFECT OF SENSITIZATION

N I T R I C A C I D CORROSION RATES IPM

la n W Heat N o . Type Annealed 2050°F S e n s i t i z e d 1200°F Ra t io

FVll 30 Cr-25 N i .00024

GD44 Type 310 Cb 4 .02 C .00024

FY79 Type 309 Cb .00028

FV 19A Type 310 + .020 C .00019

FY78 Type 309 -+ .026 C .00022

.00034 1.4

.00041 2.2

.00029 1 . 2

.00046 2 . 1

.00039 1.4

I f t h e increased r a t e s (even without i n t e r g r a n u l a r a t t a c k ) have any s i g n i f i c a n c e ,

then t h e r e aga in appears t o be a high degree of promise f o r Heat GD44, t h e Type 310

with .02% carbon and .22% columbium.

Based on t h e co r ros ion t e s t r e s u l t s and

V I I , A - 7 , B-6 and V I I I , c e r t a i n observa t ions

( a ) The n i t r i c -HF s o l u t i o n is far more

v i s u a l l o c a l i z e d a t t a c k .

(b) End g r a i n a t t a c k i s a problem wi th

a r e a r a t i o i s apprec i ab le . Laboratory h e a t s

Page 29

v i s u a l s t u d i e s r epor t ed i n Tables

can now be made:

severe i n i t s e f f e c t t o produce

heavy s e c t i o n s where edge t o s u r f a c e

a r e more prone t o show t h i s t han

commercial product ion m a t e r i a l . In a c t u a l equipment, t h i s would not be t h e s e r i o u s

f a c t o r i t i s he re .

( c ) P i t t i n g of t h e weld s u r f a c e and e s p e c i a l l y ends can have a s e r i o u s

in f luence on

I (d ) No

weld a t t a c k .

( e > I n

co r ros ion r a t e i n HN03-HF t e s t s .

v i s u a l end g r a i n a t t a c k is observed i n ' t he complex mixture , nor s eve re

s p i t e o f mild p i t t i n g on the ends of t h e weld ( a r e a C ) on GD44, r e s u l t s

i n d i c a t e t h a t .020% carbon Type 310 Cb p resen t s t h e b e s t co r ros ion r e s i s t i n g as-welded

s u r f a c e f o r t h e "03-HF s o l u t i o n s . Heat FV20, a 30 Cr-20 N i a l l o y is a l s o good.

Nei ther show l o c a l i z e d s u r f a c e attac:k. FV19A, a .020 carbon Type 310 a l s o showed

a gray e t ch i n t h e h e a t a f f e c t e d zone, bu t co r ros ion r a t e s were high due t o a c.om-

b i n a t i o n of weld p i t t i n g and end g r a i n a t t a c k .

( f ) Regardless of l o c a l i z e d a t t a c k e f f e c t s , t h e Type 310 compositions and. t h e

high C r - N i a l l o y s a r e supe r io r t o Type 309 i n both media.

(g ) Heats RV294, RV297, FY78 and M79, t h e Type 309 s e r i e s , a l l show a t t a c k

immediately ad jacen t t o t h e weld (aZea F on drawing Figure 6 ) i n t h e C L .:lex so lu -

t i o n , but none i n t h i s a r ea when sub jec t ed t o "03°F tes ts .

Metal lographic Examinat ion:

Samples of welded p l a t e were a l l sub jec t ed f i r s t t o examination a t 30X magnifica-

t i o n t o examine t h e su r face , welds and hea t a f f e c t e d zones more c r i t i c a l l y and then

each was c u t , me ta l log raph ica l ly pol i shed , e tched with oxa l i c e tchant and examined a t

250X. The examination a t 30X was q u i t e s u r p r i s i n g .

,\ . .- . . ... . . . . . . . . . . .. . . _ . I . .~ . .

Page 30

A . 30X Study

A s e a r l i e r r epor t ed , no i n t e r g r a n u l a r a t t a c k could be seen on t h e b o i l i n g 65%

n i t r i c a c i d samples. It appears t h a t t h e n i t r i c a c i d t e s t s i s not a s s e n s i t i v e a s

t h e o the r two s o l u t i o n s f o r d e t e c t i n g i n t e r g r a n u l a r s u s c e p t i b i l i t y . An examination

of weld samples a f t e r t e s t i n g i n HN03-HF s o l u t i o n s and the complex mixture revea led

t h e observa t ions r epor t ed i n Table I X .

.25M HF showed t h e same r e s u l t s a s i n t h e t a b l e bu t t o somewhat l e s s e r degree .

Tes t s i n 13M HN03-.075M HF and 13M "03-

TABLE I X

30X STUDIES FOR SURFACE ATTACK BY HNO3-HF AND COMPLEX SOLUTIONS

Heat No.

I FV71

F v l l

FV20

FV 70

FV 19B

FV 56

Fv57

FV17A

FV 19A

GD44

RV296

RV296

RV297

Type

35 Cr-20 N i

30 Cr-25 N i

30 Cr-20 N i

30 Cr-15 N i

310 + 1 S i

310 + . 03 S i

310 + . 2 8 S i

310 + . 33 Mn

310 + .02 C

310 + Cb

309 + .008 C

309 f .004 C

309 + .008 C

13M "03 -t .5OM HF

Line 1/8" from weld. No I G

I G ad jacent t o weld

No I G

No I G

Etch 1/4" from weld

No I G

N o I G

P i t s ad j acen t t o weld

Etch 1/4" from weld

No I G

Undercut weld. No I G

Undercut weld. No I G

Undercut we1.d. No I G

Complex __

'End g r a i n a t t a c k . No I G

Deep g r a i n boundary e t ch -a l so i n weld

No I G

No I G

Deep g r a i n boundary e t ch -a l so i n weld

No I G

Deep gra in boundary etch-also i n weld

Deep g r a i n boundary e t c h - a l s o i n weld

Deep g r a i n boundary e t ch -a l so in we Id

Deep , g r a i n boundary e t ch -a l so i n weld

Very rough I G s u r f a c e

Very rough I G s u r f a c e . I G a t edge of weld

Very rough I G su r f ace . I G alt edge of weld

TABLE I X (contd) --

Heat No. Type 13M HNO3 + .50M HF

FY78 309L Etch 1/4" from weld

FY 79 309 C Severe a t t a c k of weld

The cond i t ion observed on t h e complex s o l u t i o n

Page 31

C-gmp 1 ex

Deep g r a i n boundary e t ch . Also I G

Rough I G su r f ace . Deep I G a t edge of weld

samples was s t a r t l i n g s i n c e it

occurs i n base meta l completely unheated by welding. The unusual deep g ra in boundary

e t ch o r perhaps i n t e r g r a n u l a r s u r f a c e a t t a c k i s p i c t u r e d i n F igure 7 taken a t 3 0 X on

sample FV19A. Note t h a t t h e a t t a c k occurs a l s o a long g r a i n boundaries i n t h e weld.

This c o n d i t i o n i s not t h e commonly observed i n t e r g r a n u l a r s u r f a c e a t t a c k sometimes

encountered a f t e r annea l ing and p i ck l ing . It was a l s o q u i t e ev ident on machined and

pol i shed edges; such edges were prepared a s a f i n a l s t e p be fo re c o r r o s i o n t e s t i n g and,

t h e r e f o r e , never had any annea l s c a l e on them. Based on subsequent 250X microscopic

examination, t h i s i n t e r g r a n u l a r e t ch ogcurs i n t h e absence of v i s i b l e g r a i n boundary

p r e c i p i t a t e . A t t h e p re sen t t ime t h i s phenomenon i s not understood but p o i n t s t o a

p o s s i b l e i n v i s i b l e p r e c i p i t a t e of some type t h a t is s e n s i t i v e t o a t t a c k i n t h i s

s p e c i f i c complex s o l u t i o n environment. In c o n t r a s t t h e more s e v e r e l y c o r r o s i v e

HN03-HF s o l u t i o n s d i d not produce i t i n any ins tance .

I

Another i n t e r e s t i n g f a c e t of t h i s unusual g r a i n boundary e t ch e f f e c t i s t h a t i t

does no t occur with t h e duplex s t r u c t u r e s i n Heats FV70, FV71 and FV20. The s u r f a c e

a t t a c k can occur f a r from any weld; it does not p e n e t r a t e a f u l l g ra in deep, and a s a

ma t t e r of f a c t could not be seen i n a 250X microscopic examination of t h e c r o s s sec -

t i o n . Because of our concern

samples which had been t e s t e d

t o view samples wi th a 2050'F

about t h i s s e r i o u s cond i t ion , we

i n t h e complex s o l u t i o n ; h e r e we

anneal and a 2150'F annea l . The

i n Table X.

examined a l l sheet:

had an oppor tun i ty

r e s u l t s a r e t a b u l a t e d

j _ . .-. - , . , - . ,.... .:..> :. . . -1. - . .. . . .. _. . . . .. . . .. . - . .

Y

F i l m G993

FIGURE 7

Sample FV19A

30X

Showing Deep Grain Boundary Etch i n Base Metal and Weld' After Tests i n Complex Mixture

,- . - ..... .. _ _ . ~ .,... ..,. .

Page 32

TABLE 5

30X EXAMINATION OF SHEET SAMPLES AFTER COMPLEX SOLUTION TEST

Heat No. Type - 2050°F 2150°F

FV71 F v l l FV20 FV 70 FV 1 9 B FV56 FV17A FV 19A GD44 RV296 RV294 RV29 7

I FY78 FY 79

35 Cr-20 N i 30 Cr-25 N i 30 Cr-20 N i 30 Cr-15 N i 310 + 1.0 S i 310 + .03 S i 310 i . 33 Mn

310 Cb 310 + .02 C

309 + .008 C 309 + .004 C 309 + .008 C 309L 309 Cb

No NO

N o No Trace Yes Yes-mild Yes Yes-s evere Ye s - s ever e Yes - s ever e Yes -sever e Yes -sever e Trace

No Yes No NO

Heavy No Yes - m i Id Yes -sever e Yes Yes -sever e Yes -sever e Yes -sever e Yes - s ev e r e Yes -heavy

It may be concluded t h a t t h e r e probably is a s u s c e p t i b l e p r e c i p i t a t e of some

type t h a t i s i n most ca ses formed a t h igher temperatures . We have been unable t o

s e e any p r e c i p i t a t e microscopica l ly . It could expla in t h e ex i s t ence of heavier o r

g ra in boundary a t t a c k on Type 309 m a t e r i a l s commencing immediately a t t h e edge of

t h e weld and extending a s h o r t d i s t a n c e i n t o t h e base meta l , f o r t h i s a r ea has reached

very high temperatures (above 2050°F) next t o the fus ion zone. While t h e a t t a c k may

be too s u p e r f i c i a l t o be d e t e c t e d i n co r ros ion r a t e s , neve r the l e s s i t should be of

concern and deserves much f u r t h e r i n v e s t i g a t i o n beyond t h e scope of t h i s a l l o y develop-

ment program.

B . Metal lographic S tud ie s

A l l t h e samples were examined me ta l log raph ica l ly t o e s t a b l i s h s t r u c t u r e s and

presence of g r a i n boundary p r e c i p i t a t e s . I n a d d i t i o n they were examined f o r evidence

of s u r f a c e a t t a c k . The r e s u l t s a r e summarized i n Tables X I and X I 1 and i l l u s t r a t e d

with a s e r i e s of photomicrographs t h a t fol low.

... .

Page 33

:n TABLE XI -- - METALLOGRAPHIC EXAMINATION OF WELD HEAT AFFECTED ZONE

AFTER TESTS I N COMPLEX MIXTURE

Wre Id A t t a c k

None

None

None

None

"one

None

None

None

None

None

None

None

None

None

None

None

De l t a F e r r i t e

Yes

None

Yes

Yes

None

None

None

None

None

None

None

Trace

Trace

Trace

Trace

None

Weld - 'u Heat Eo. Type Grain Boundary Carbides i n Heat Af fec t ed Zone S u r f a c e At t ack

None -

B FJ71

P Fv20

5 FV70

-_ EV 19B

-

FV56

0 Fv57

L FV 19A

FV 1 7 B

GD44

RV29 6

RV294 ' RV297

R FY78

P FY79

l-3

35 Cr-20 N i

30 Cr-25 N i

30 Cr-20 N i

30 Cr-15 N i

310 -L 1 S i

310 + .03 Si

310 + .28 S i

310 + .33 Mn

310 1- .020 C

310 + .018 C

310 + Cb

309 + .008 C

309 + .004 C

309 + .008 C

309 + .026 c

309 + Cb

310

3 10

3 10

3 10

3 10

3 10

3 10

3 10

3 10

3 10

GD44

RV296

RV294

RV297

N78

FY79

Very s 1 i g h t p r ec i p i t a - t ion

Continuous Some I G a t t a c k

None

None

Trace

None

'None

Some discont inuous p r e c i p i t a t i o n

None None

None Very l i g h t p r e c i p i t a - t i on

None None

Very l i g h t p r e c i p i t a - tr ion

None

None

None

None

None

Nos e

None

None

I, igh t p r ec i p it a t i on

Very l i g h t

None

Very l i g h t p r ec i p i t a - t ion

Very l i g h t p r e c i p i t a - t ion

L igh t p r e c i p i t a t i o n

None

There was no microscopic evidence of i n t e r g r a n u l a r a t t a c k ad jacen t t o t h e weld

on any of t h e Type 310 m a t e r i a l s . Among t h e h igh C r - N i a l l o y s only t h e 35 C r - 2 Q N i

composition showed any evidence of a t t a c k a d j a c e n t t o t h e weld. These r e s u l t s a r e

: . , . . .... ... . ... . . . . . . . . _ I _ . . . . . . . . .

Page 34

encouraging s i n c e t h e Type 310 Cb and the ,020 C Type 310 which a r e promising have

showrl ne inLergranular o u s c o p f i b i l i t y i n t h i e envirenmenf, and in a d d i f i e n Ghca w@hd

depos i t of .018% carbon Type 310 (from Heat FV17B) shows no s u s c e p t i b i l i t y . Even t h e

h e a t s , RV294, RV297, and N 7 9 , which showed i n d i c a t i o n of a heav ie r l i n e of a t . tack

a t t h e hea t a f f e c t e d zone v i s i b l e on t h e edges of welded p l a t e specimens, do n o t show

s e r i o u s i n t e r g r a n u l a r p e n e t r a t i o n o r g r a i n i n e s s when examined me ta l log raph ica l ly a t

250X.

F igures 8 t o 14 i n c l u s i v e were s t r u c t u r e s a t t h e s u r f a c e of va r ious samples a f t e r

t e s t i n g i n t h e complex s o l u t i o n s . These have been s e l e c t e d t o i l l u s t r a t e va r ious

r e p r e s e n t a t i v e s t r u c t u r e s and what they show a f t e r co r ros ion t e s t s i n t h i s environ-

I ment.

F igure 8 i s a photograph of Heat FV11, t h e a u s t e n i t i c 30% Cr-25 % N i s t e e l i n

t h e weld hea t a f f e c t e d zone.

and d e f i n i t e i n t e r g r a n u l a r a t t a c k a t t h e s u r f a c e .

Note the presence of a cont inuous c a r b i d e p r e c i p i t a t e

F igure 9 i s a duplex a u s t e n i t i c - f e r r i t i c s t r u c t u r e of Heat FV71, a 30 Cr-15 N i

a l l o y i n t h e weld hea t a f f e c t e d zone. There was no v i s u a l evidence of a c c e l e r a t e d

a t t a c k a t weld h e a t a f f e c t e d zones and t h i s i s confirmed by a microscopic examination.

F igures 10 and 11 rep resen t Type 310 h e a t s without a g ra in boundary p r e c i p i t a t e

i n the weld h e a t a f f e c t e d zone. Note t h e ve ry rough s u r f a c e i n F igure 10; t h i s was

p re sen t a l l over the s u r f a c e of t h e base meta l even i n a r e a s remote from weld h e a t

a f f e c t e d zones. This could be t h e s u r f a c e e t ch descr ibed above and shown i n Fi.gure

7 , bu t no te t h a t t h i s is a m a t e r i a l which has no v i s i b l e g r a i n boundary p r e c i p i t a t e .

In Figure 11 some discont inuous p r e c i p i t a t e i s v i s i b l e i n t h e hea t a f f e c t e d zone, and

t h e r e i s some s l i g h t evidence of a t t a c k of a p i t t i n g n a t u r e bu t no t n e c e s s a r i l y a t

t h e g r a i n boundaries .

F igure 12 i s t h e vacuum melted Heat RV296 with ve ry low

d e l t a f e r r i t e . The a rea shown i s immediately bes ide t h e edg

carbon

of t h

which shows

weld. There i s

Page 35

no g r a i n boundary ca rb ide p r e c i p i t a t e , ye t some t r a c e s of s u r f a c e e t ch a r e apparent .

The s u r f a c e appears t he same i n base meta l a r e a s remote from t h e weld hea t a f f e c t e d

z:6tie.

Figure 13 r e p r e s e n t s .02% carbon Type 310 Cb i n t h e weld hea t a f f e c t e d zone.

The t r a c e amounts of d i scont inuous g r a i n boundary p r e c i p i t a t e have not promoced any

i n t e r g r a n u l a r co r ros ion . The s u r f a c e showed t h e unusual g r a i n

examined a t 30X bu t t h e cond i t ion e x i s t e d a l l over t h e s u r f a c e

weld hea t a f f e c t e d zones.

boundary e t c h when

and not confined t o

F igure 14, t h e Type 309 Cb weld, showed no evidence of a t t a c k i n t h e complex

b o i l i n g mixture . This i s i n s u r p r i s i n g c o n t r a s t t o t h e performance of t he same weld

i n b o i l i n g "03-HF s o l u t i o n p i c t u r e d i n Figure 19 l a t e r . I

Table X I 1 dea l s wi th microscopic examination a t 2 5 0 X of samples t h a t showed any

susp ic ion of p o s s i b l e i n t e r g r a n u l a r co r ros ion i n t h e b o i l i n g HN03-HF s o l u t i o n s . Again

i t was seen t h a t no i n t e r g r a n u l a r co r ros ion had occurred i n t h i s s o l u t i o n o t h e r than

t h e one in s t ance of FV11, t he a u s t e n i t i c 30 Cr-25 N i a l l o y which a l s o was a t t a c k e d i n

t h e complex s o l u t i o n .

The a t t a c k i n HN03-HF s o l u t i o n s on t h e a l l a u s t e n i t i c samples i s seve re and

appears a s i n F igure 15. No a t t a c k i s evident a t g r a i n boundaries i n s p i t e of t h e

d iscont inuous p r e c i p i t a t e .

F igure 16 d e a l i n g wi th Heat FV-11 shows i n t e r g r a n u l a r a t t a c k a s ' expec ted . F igure

1 7 i s t h e duplex s t r u c t u r e 35 Cr-20 N i hea t a t t he h e a t a f f e c t e d zone. The same

s t r u c t u r e and s u r f a c e a t t a c k i s a l so seen a t a r e a s remote from t h e hea t a f f e c t e d zone.

The

Although

t h e r e i s

f i n a l two f i g u r e s , 18 and 19, show t h e Type 309 Cb base meta l and weld,.

F igure 18 shows no s u r f a c e a t t a c k i n t h e hea t a f f e c t e d zone bes ide the weld,

s e r i o u s d e t e r i o r a t i o n of t h e weld i t s e l f (F igu re 19 ) . There i s no evidence

from meta l lographic examination t o expla in t h e r a p i d co r ros ion of t h e Type 309 Cb i n

"03-HF s o l u t i o n .

of d e t e r i o r a t i o n .

The Type 310 Cb weld i n t h i s program i s not s u b j e c t t o t h i s type

-. . . . ~ . . . . . . . . . . . .

FIGURE 8

P l a t e 200E8

250X Oxal ic

,Heat FVl l

Weld Heat A f f e c t e d Zone A f t e r

T e s t i n Complex- S o l u t i o n

F I G U R E 9

P l a t e 200E9

250X Oxal ic

Heat F’V71

Weld Heat A f f e c t e d ’Zone A f t e r

T e s t i n Complex S o l u t i o n

,

...... ........ ..... .... ........ _- ..-.. ~. .~... . - ..I_---. .. -. ........... - .- . . . . . . . . . . . . . . .

FIGURE 10

P l a t e 200E10

250X Oxal ic

Heat FV17A

Weld Heat Af fec t ed :Zone A f t e r

T e s t i n Complex .Solu t ion

FIGURE 11

P l a t e 2 0 0 E 7

250X Oxal ic

Heat FV19B

Weld Heat Af fec t ed Zone A f t e r

T e s t i n Complex S o l u t i o n

I

FIGURE 12

P l a t e 201E3

250X Oxalic

Heat RV296

Weld Heat A f f e c t e d Zone A f t e r

T e s t i n Complex S o l u t i o n

FIGURE 13

P l a t e 201E1

250X Oxalic

Heat GD44

Weld Heat A f f e c t e d Zone A f t e r

T e s t i n Complex S o l u t i o n

FIGURE 14

P l a t e 201E2

250X Oxalic

Heat FV79

Weld i n Heat FV79 Type 309Cb

A f t e r T e s t i n Complex Mix tu re

FIGURE 15

P l a t e 201E7

250X Oxalic

Heat FV 19B

Weld Heat A f f e c t e d >!one A f t e r

T e s t i n 1 3 M "03 - .50M H F

.... ... .... ........ ...... . . . ......... - - . . . ~ , i __I--. -__._ ~

.. .- &-- ._

i; b

FIGURE 16

P l a t e 201E8

250X Oxalic

Heat FVll

Weld Heat Af fec t ed Zone A f t e r

T e s t i n 1x1 "03. - .50M HF

FIGURE 17

P l a t e 201E4

250X Oxal ic

Heat FV71

Weld Heat Af fec t ed Zone A f t e r

Test i n 1% HNO3 - .50M HF

. . . . . . . . . ........ . .... _ ._.. _. . . . . . . . . ........ .......... . . . . . . . . . . . . --

I .

FIGURE 18

P l a t e 201E5

250X Oxalic

Heat FV79

Weld Heat Affec ted Zone A f t e r

T e s t i n 1 3 M "03 - .50M HF

FIGURE 13

P l a t e 201E6

250X Oxalic

Weld in Heat FV79 A f t e r

T e s t i n 1% "03 - .50M HF

- TABLE X I 1 --

METALLOGRAPH1.C EXAMINATION OF WELDED 1 / 4 " PLATE SAMPLES

HN03-HF TESTS

Heat Affec ted Zone --- Heat No. Weld Metal Area Next t o Weld Area -1/8" from Weld

FV 19B A l l a u s t e n i t i c No p r e c i p i t a t i o n ca rb ides Some discont inuous p r e c i p i t a t i o n

F v l l P o s s i b l e t r a c e of f e r r i t e No p r e c i p i t a t i o n

FV 19A A l l a u s t e n i t e N O p r e c i p i t a t i o n

F V 7 1 Cons iderable f e r r i t e -30% f e r r i t - e i n base metal

Continuous pr ec i p i t a t ion ca rb ides - i n t e rg ranu la r at- t a c k

S l i g h t amount discont inuous prec i p i t a t ion

-30% f e r r i t e , prnbably p r e c i p i t a - t i o n a long f e r r i t e a u s t e n i t e

Fv 56 A l l a u s t e n i t e No p r ec i p i t a t ion No p r e c i p i t a t i o n

FY79 -5% f e r r i t e Trace of f e r r i t e with p r e c i p i t a t i o n along f e r r i t e - a u s t e n i t e boundaries

Trace of f e r r i t e with p r e c i p i t a t i o n along f e r r i t e - a u s t e n i t e boundaries

W cn

Page 37

The microexamination of weld co r ros ion t e s t specimens has revea led t h e fo l lowing

s i g n i f i c a n t conclus ions .

1. Although t h e HN03-HF s o l u t i o n s a r e h ighly c o r r o s i v e i n n a t u r e they do not

produce i n t e r g r a n u l a r a t t a c k except: where a continuous g r a i n boundary p rec ip i t . a t e

i s p re sen t .

2 . I n c o n t r a s t t h e complex s o l u t i o n appears capable of caus ing i n t e r g r a n u l a r

e tch ing ( o f a s u p e r f i c i a l na tu re l e s s than a g r a i n deep) of t h e a u s t e n i t e s t r u c t u r e s

even i n t h e absence of a v i s i b l e g ra in boundary p r e c i p i t a t e ; i t does not do t h i s

with duplex s t r u c t u r e s . The i n v i s i b l e p r e c i p i t a t e o r g ra in boundary cond i t ion appears

t o be more seve re wi th higher annea l ing temperatures . Th i s could exp la in t h e l o c a t i o n

of apprec i ab le i n t e r g r a n u l a r a t t a c k immediately a t t h e edge of weld fus ion zones i n

Type 309L o r 309 Cb m a t e r i a l s which extends an apprec i ab le d i s t a n c e i n t o t h e base

metal , d iminish ing i n i n t e n s i t y a s t he d i s t a n c e inc reases . Such a t t a c k does not

i

I

occur i n a sharp , deep l i n e , l i k e t h e so -ca l l ed k n i f e - l i n e a t t a c k seen with welded

and s e n s i t i z e d Type 347 or Type 309 Cb. This apprec i ab le band a t t a c k next t o the

fus ion zone does not occur on any o f t h e Type 310 compositions included i n t h i s pro-

gram.

3. With t h e except ion of t he 30 Cr-25 N i Heat F V l l t h a t had cont inuous g r a i n

boundary p r e c i p i t a t e , microscopic examination a f t e r t h e HN03-HF t e s t s a t 250X was

not a b l e t o r e v e a l any i n t e r g r a n u l a r co r ros ion o r g r a i n f a l l - o u t a t t h e surface: of

any compositions included i n t h e program. Even t h e J?V vacuum melted h e a t s showed no

a t t a c k a t t he edge of t he fus ion zone i n HN03-HF, a l though they d e f i n i t e l y were

a t t a c k e d i n t h e complex s o l u t i o n , v i s i b l e on t h e machined ends.

4 . Heat GD44, Type 310 Cb, showed no i n t e r g r a n u l a r a t t a c k i n any of t h e so lu -

t i o n s , e i t h e r i n the a s welded cond i t ion o r a f t e r s e n s i t i z i n g . It i s s u b j e c t , how-

eve r , t o t h e mild s u r f a c e i n t e r g r a n u l a r e t ch s i m i l a r t o a l l t he o t h e r a u s t e n i t i c

compositions, b u t which i s not s e r i o u s .

. .. - . .. .. . . . .. ~. .... ~ . . . - . . . . .. . . ., ..

Page 38

5 . There i s no explana t ion (no s t r u c t u r a l p e c u l i a r i t y ) why Type 309 Cb welds

a r e s u b j e c t t o s eve re d e t e r i o r a t i o n i n b o i l i n g "03-HF s o l u t i o n s b u t unaf fec ted by

t h e complex s o l u t i o n . The Type 310 Cb weld was unaf fec ted by e i t h e r s o l u t i o n .

6. I n those in s t ances where t h e HNO3-HF s o l u t i o n produces a n apparent gray

e t ch i n h e a t a f f e c t e d zones, with t r a c e g ra in boundary p r e c i p i t a t e , t h i s a t t a c k i s

s u p e r f i c i a l (no t more than .001" deep) and i s not i n t e r g r a n u l a r o r graying in n a t u r e .

Conclusions of I n v e s t i g a t i o n :

1. Resu l t s of t h e i n v e s t i g a t i o n i n d i c a t e t h a t .02% carbon Type 310 Cb o r

.02% carbon Type 310 both a r e an improvement over Type 309L and Type 309 Cb i n t h e

n i t r i c - h y d r o f l u o r i c and complex s o l u t i o n s from t h e s tandpoin t of genera l co r ros ion

5 a t e s . A l l of t h e h igh C r - N i a l l o y s show improved c o r r o s i o n r a t e s over both Types

309 and 310 compositions i n HN03-HF s o l u t i o n s , but t h e h igh C r - N i a l l o y s a r e about

comparable t o Type 310 m a t e r i a l s i n t h e complex mixture .

2. A l l of t h e Type 310 a l l o y s , 2 s wel l a s Heat FV11, a 30 Cr-25 N i a l l o y ,

a r e f u l l y a u s t e n i t i c . Corrosion r a t e s i n any of t h e environments does not appear

t o be a f f e c t e d by t h e presence o r absence of f e r r i t e ; r a t h e r i n s t ead t h e i r a l l o y

con ten t has a dominant i n f luence , with chromium being s t r o n g e s t and n i c k e l less , .

Only i n 6% FeC13 does f e r r i t e appear t o have an in f luence i n promoting p i t t i n g .

3 . S i l i c o n and manganese v a r i a t i o n s have perhaps s l i g h t e f f e c t on co r ros ion

i n t h e va r ious environments, bu t not. s u f f i c i e n t t o cons ider such v a r i a b l e s a s

s u f f i c i e n t t o improve co r ros ion r e s i s t a n c e t o t h e poin t d e s i r e d . High s i l i c o n may

be a disadvantage i n 65% "03.

4 . I n weld t e s t s on p l a t e , co r ros ion t e s t s i n HN03-HF and t h e complex mixture

a r e t h e only ones capable of developing i n t e r g r a n u l a r a t r a c k on t h e a l l o y s i n t h i s

program.

t e n i t i c 30 Cr-25 N i a l l o y (with .084% N) i n t h e h e a t a f f e c t e d zone. The complex

s o l u t i o n showed severe i n t e r g r a n u l a r a t t a c k of t he same Heat FVll and a c c e l e r a t e d

The HN03-HF s o l u t i o n caused d e f i n i t e i n t e r g r a n u l a r a t t a c k of FVll t h e aus-

. . . . . . . . . . . . . . . . . . - . . - - . - . - . - -

Page 39

a t t a c k a t t h e edge of t h e fus ion zone on Heats RV294, RV297, FY79, a l l Type 309 o r

309 Cb h e a t s .

5 . Light gray e t ch ing by "03-HF s o l u t i o n s i n heaiz a f f e c t e d zones of Heats

FY78 ( .02% carbon Type 309), and t h e fo l lowing Type 310 h e a t s , F V 1 7 A y FV19Ay FY19B,

and FV56, was very s u p e r f i c i a l and d e f i n i t e l y not i n t e r g r a n u l a r i n na tu re .

6 . Severe weld a t t a c k of Type 309 Cb occurs i n "03-HF but no t t h e complex

s o l u t i o n .

7 . The complex mixture produces a s u p e r f i c i a l i n t e r g r a n u l a r e t ch a t g r a i n

boundaries i n a u s t e n i t i c s t r u c t u r e s v i s i b l e a t 30X even i n t h e f u l l y annealed condi-

t i o n when no g ra in boundary p r e c i p i t a t e can be seen. The a t t a c k appears t o be worse

y i t h h ighe r annea l ing temperatures .

an i n t e r e s t i n g phenomenon t o i n v e s t i g a t e .

The mechanisms . a r e not understood and would be

8. It has been demonstrated t h a t a n improved co r ros ion r e s i s t a n t a l l o y lover

Type 309L and Type 309 Cb has been a t t a i n e d i n t h i s i n v e s t i g a t i o n .

.02% carbon Type 310 Cb, o f f e r s t h e b e s t promise among t h e Type 310

It shows much b e t t e r co r ros ion rate:; i n b o i l i n g HN03-HF and complex

Types 309L o r 309 Cb, and i s not s u b j e c t t o i n t e r g r a n u l a r a t t a c k i n

Heat G D 4 4 , t h e

compositioins.

s o l u t i o n s than

weld h e a t a f f e c t e d

zones i n any of t h e environments. This a l l o y i s f u l l y a u s t e n i t i c and demonstrated it

could, on a l abora to ry s c a l e , be hot: f i n i s h e d and co ld f i n i s h e d s a t i s f a c t o r i l y t o

p l a t e and s h e e t .

u n l i k e Type 309 Cb, showed no a c c e l e r a t e d co r ros ion of t h e weld depos i t .

It welded s a t i s f a c t o r i l y wi th f i l l e r of t h e same composition, and,

9 . Because of t h e i r even bett :er co r ros ion r e s i s t a n c e , t h e high C r - N i al i .oys

o f f e r p o s s i b l e f u t u r e promise. They a re duplex s t r u c t u r e s (except f o r Heat FV11, a

30 Cr-25 N i a l l o y with .084% N) and a s such would be very d i f f i c u l t t o process i n t o

va r ious wrought forms. The encouragement provided by hea t FVll i s overshadowed by

i t s i n t e r g r a n u l a r s u s c e p t i b i l i t y . More should b e learned about t h e e f f e c t s of carbon

and n i t r o g e n i n t h e s e h igher a l l o y s i n regard t o s i n g l e phase s t r u c t u r e and i n t e r -

Page 40

granu la r s u s c e p t i b i l i t y , i n view of t h e i r ve ry low c o r r o s i o n r a t e s .

W. C. Renshaw Allegheny Ludlum S t e e l Corpora t ion

Research Center Brackenridge, Pennsylvania

WGR : ga

October 23, 1962

Q I

H e a t No. -- FV-70

I 1

1 1

I 1

FV-19B I 1

I I

I 1

ly-11 I 1

I I

II

FV-19A I 1

I 1

I 1

Fv-20 I1

I 1

I 1

FV-17A I I

1 1

I I

Fv-71 I1

1 1

I 1

FV-56 I I

I 1

I 1

, FV-57

Ann ea 1 ed a %

2050°F 2050 2 150 2 150

2050°F 2050 2150 2 150

2050°F 2050 2 150 2 150

2050°F 2050 2 150 2 150

2050°F 2050 2150 2 150

2050°F 2050 2150 2150 '

2050°F 2050 2 150 2150

2050°F 20 50 2 150 2150

2050°F 2050 2 150 2150

TABLE A-1 - -- CORROSION RESULTS I N B O I L I N G SOLUTIONS

OF 13M HNO3 $. .075M HF

ON SHEET (SfX 24 HOUR P&RIObS)

A Corrosion Rate IPM 1

.0187

.0182

.0190

.0193

.0212

.0202

.0241

.0241

.0127

. 0 124

.0072

.0226

.0211

.0215

.0245

.0242

.0141

.0136

.0184

.0190

.0237

.0239

.0359

.0360

,0133 .0163 .0150 .0145

.0244 ,0192 .0264 .0247

.0183

.0177

.0206

.0220

2

. 0 165

.0165

.01'76

.01'79

. 0 182

.0171

. O N 7

. 0 148

.011.7

. 0 11.5

.0103

.0102

.0148

.0149

.0075

.0176

.0134

.0134

.0134

.0131

.0237

.0246

.0301

.0301

.0074

.0088

.0128

.0122

.0185

.0146

.0187

.0172

.0151

.014 1

. O l O l S

.0113

-- 3 4

.0182

.0185

.0159 0164

.0174

. 0 163

.0150

.0152

.0107

. 01.09

.0086

.0084

.0181

. 0 1.84

.0144

.OM4

.0135

.0134

.0130

.0132

.0244

.0245

.0284

.0284

.0117

.0138

.0131

.0125

.0220

.0173

.0208

.0192

.0169 0157

.0161

.0174

.0168

.0170

.0168 ,0172

.0173

.0163

.0182 : .OL84

.0083

.0076

.0108

.0107

.0130

.0134

.0129

.0129

.0096

.0096

.0132

.0126

.0186

.0241

.0286

.0287

.0110

.0130

.0134

.0128

.0204

.0160

.0187 0173

.0148

.0138

.0159

.0172

5

.0179

.0181

.0172

.0178

.0166

.0156

.0181

.0181

.0108 ,0105 .0079 .0079

.0120

.0122

.0153

.0153

.0120

.0117

.0115

.0114

.0255

.0219

.0266

.0266

.0103

.0122

.0115

.0109

,0186 .0124 .0136 .0126

.0156

.0144

.0145

.0157

6

.0163

.0164

.0176 ,0182

.0124

.011.6

.0168

.0168

.0073

.0072 ,0075 .0070

,0094 .0096 .0135 .0139

.0063

.0062

.0093

.0091

.0174

.0187

.0296

.0301

.0086

.0103

.0105

. 0100

.0150

.0118

.0136

.0125

.0077

.0113

.0195

.0212

- ilvg,

.0174

.0175

.0174

.0178

.0172

.0162

.0178

.[I179

, 0103 . C I l O O .0087 .0111

.0147

.O 150

.0164

.0164

.0115

.0113

.0131

.0131

.0222

.0230

.0299

.0300

.0104

.0124 '1 0127 .0122

.0198

. 0 152

. O 186

. 0 173

. o L47 -0145 .0:162 .o:t75

.. . . ., .... _.._. -- . . . .. . .. . ~ .. . ... . .. ... . . . -.. .- . . . . - . . . . . . . . , - .

U -..

Heat No. Y FY-78

I t

1 1

I1

RV-296 I 1

I 1

I 1

RV-294 I 1

11

I 1

RV-297 I 1

I 11

FY-79 I 1

I 1

I 1

GD-44 I 1

I 1

I 1

Annea led a t

2056°F 2,050 2 150 2150

2050'F 2050 2 150 2 150

2050°F 2050 2 150 2 150

2050°F 2050 2150 2 150

2050°F 2050 2 150 2150

2050°F 2050 2 150 2150

-- TABLE A - 1 ( c o n t d )

Corros ion R a t e IPM 7 - c L

.0206

.0206

.0304

.0299

.0277

.0285

.0308

.0308

.0277

.0278

.0288

.0287

.0267

.0272

.0233

.0240

.0285 ,0275 .0236 .0239

.0171

. 0 1 7 7 ,0173 .0175

.0291

.0287

.0300

.02!30

.0262

.0270

.0271

.0272

.0251

.0255

.0205

.0203

.0161

.ole12

.021.0

.0209

.0262

.026 1

.023@

.0228

.0151

.0153

.0138

.0139

3

.0317

.0313

.0248

.0329

.0216

.0224

.0218 -0220

.0167

.0168

.0209

.0206

.0221

.0221

.0164

.0164

.0250

.0249

.0358

.0137

.0124

.0126

.0112

.0154

4

.0275

.0272

.0202

.0195

.0183

.0189

.0154

.0155

.0158

.0159

.0163

.0160

.0176

.0176

.0176

.0146

.0195

.0194

.0184

.0188

.0121

.0123

.0129

.0129

- J

.0238

.0235

.0153

.0146

.0131

. 0 136

.0175

.0177

.0168

.0169

.0x3

.0181

.0182

.0182

.0147

.0171

.0248

.0248

.0224

.0228

.0128

.0129

.0128

.0128

.0210 .I3256

.0207 .0e3

.0143 . (3225

.0137 .0233

.0117 .(I198

.0121 ' .020Lr

.0120 .0208

.0121 .(I209

.0122 .019 1

.0124 " 0192

.0128 a 0196

.0125 . .0194

.0125 .0189

.0125 .0190

.0150 . 0180

.0174 .0184

.0124

.912,5 ,0122 .0125

.0089

.0090

.0082

.0082

.0227

.022.5

.0226

.0191

.Q131

.0133

.0127

.0135

. -

Hear N O .

ET-70 I 1

I 1

I 1

1 1

I 1

FV-19B I 1

I 1

1 1

1 1

I 1 1

FV- 11 11

II

I 1

S I

I 1

FV - 19A I 1

I 1

I 1

1 1

I 1

m - 2 0 1 1

I 1

II

I 1

I 1

FV -17A I 1

I 1

I 1

I 1

I I

~~

Annea l e d a t

2050°F 2050 2150 2 150 2300 2300

2050'F 2050 2150 2 150 2300 2300

2050°F 2050 2 150 2 150 2300 2300

2050°F 20 50 2150 2 150 2300 2300

2050'F 2050 2 150 2 150 2300 2300

2050°F 2050 2 150 2 150 2300 2300

TABLE A-2 -- CORROSION RESULTS IN BOILING SOLUTIONS

OF 13M HNO3 t- 25M H F

ON SHEET ( S I X 2sc HOUR PERLOBS)

C o r r o s i o n R a t e IPM 1

.0437

.0439

.0328

.0326

.0542 ,0520

.0413

.0420

.0468

.0489

.0457

.0468

.0319

.0321

.0345

.0352

.0307

.0314

.0955

.0084

.0484 ,0477 .0291 .0702

.0144

.0145

.0321

.0313

.0296

.0284

.0608

.0615

.0626

.0613

.0527

.0518

2

.0335

.0341

.0376

.0382 0363

.0365

.0668

.0674

. 0 743 -0771 .03?7 .0328

.0202

.0203

.0102

.0103

.0358

.0359

.0480

.0460

.0369

.036 1

. 0 14.1

. 0 135

.0557

.0444

.0441

.0263

.0254

.0599

.0602

.0712 ,0698 .0884 .0877

----

.0551 *

3

.0373

.0382

.0335

.0339

.0350

.0352

.0262

.0264

.0301

.0312

.0374

.0388

.0282

.0283

.0204 I 0205 .0175 .0177

.0342

.0330

.0431

.0422

.0669

.0368

.0199

.019 7

.0169

.0168

.0194

.0187

.0370 * 0401 .0947 .0965 .0371 .0341

4

.0596

.0612

.0294

.0298

.0419

.0420

.0983

.1000

.0816

.0741

.0569

. os90

.0259

.0260

.0658

.0254

.0235

.0238

.0335

.0322

.0511

.0429

.0481

.0463

.0231

.0229

.0394

.039 1

.0295 ,0285

.0746

.0765

.0613

.0607

.0579

.0571

5

.0269

.0272

.0405

.0411

.0465

.0468

.0435

.0439

.0286

.029 7

.0368

.0384

.0299

.0301

.0240

.0242

.0227

.0221

.0380

.0367

.0313

.0378

.0739

.0712

.0437

.0434

.0437

.0433

.0380

.0368

.0689

.0693

.0876

.0872 ,0764 ,0755

6

.0194

.019 7

.0281

.0285

.0379

.0382

.0322

.0327

.0279

.0290

.0623

.0647

.0357'

.0361

.0224 = 0226 .0349 .0353

.0316

.0306

.0503

.049 1

.0356

.0343

.,0338

.0333

.0265

.0344

.0367

.0355

stopped 11

11

II

I I

I t

.0367

.0374

.0337

.0340

.0420

.0418

.0514

.0521

.1466

.0483

.0451

.0468

.0285

.0288

.0296

.0230

.0275

.027 7

.0468

.O3 12

. 0435

.0426

.0446 ,0454

.0318

.0315

.0338

.0348

.0299

.0289

.0602

.0615

.0755

.0751

.0625

.0612

0 a Heat No. Annea l ed

a t

2Q5Q"F 2050 2,150 2 150 2300 2300

2050°F 2050 2 150 2 150 2300 2300

2050°F 2050 2 150 2 150 2300 2300

2050°F 2050 2 150 2 150 2300 2300

2050°F 2050 2150 2150 2300 2300

2050°F 2050 2 150 2 150 2300 2300

2050°F 2050 2150 2150 2300 2300

(contd)

C o r r o s i o n Ra te IPM 1

.0192

.0201

.0208

.0194

.0263

.0242

.0472

.0457

.0468

.0482

.0511

.0624

,0462 .0431 .OM5 .0410 .0381 .0389

.0416

.0421

.0322

.0334

.0361

.0363

,0419 .0429 .039 7 .0406 .0338 .0341

.0401

.0390

.0788

.0771 ,0352 .0354

.0436

.0441

.0397

.0415

.0320

.0322

2

i 8299 .0317 . 0 1'3 1 . 0181 "0269 . .02!J5

.0343

.03:34

.039 1

.0402 0468

.0648

.059 1

.0589

.0214

.0176

.0177

.122Lc

.1214

.0248

.025 1

.0249

.02&9

.0245

.0246

.0605

.0600

.0233

.0233

.0656

.0643

.0591

.059 2

.!I584

.0603

.0721+

. p 725

.04 79

.0488

.0654

.0653

--

.021.1 "

3

e 84RX 0 0514 .0464 .044 3 " 0 2 0 3 0192

.0687

.(I696

.0775 e 0874 .0358 .0528

0313 . 0 2 9 9 .0494 .8499 .0414 .0414

.0657

.0659 ,0616 .0632 .048 1 .0482

.0876

.0892

.0483

.0480

.0447

.0452

.0428

.0421

.0738

.0735

.0651

.0667

.0549

.0544 0672

,0686 .0663 ,0662

4

Q434 .0h60 .039 7 .0378 . c201. .0192

.0292

.0284

.0218

. 0 2 m

.0458

.0667

.0485

.0472

.0474

. 0 9 2

.0289

.13289

5

8358 .0371 .0278 .0264 e 0281 .0270

.0410

.0396 ,0689 0690

.0452

.0394

a 0271 .0263 .0459 .0466 .0461 .0463

stopped 11 stopped 11

.0635 .0687

.0750 .0690

.0637 .0693

.0641 .0631

.Of337 .0583

.0648 .0592

.0579 .0563

.0573 .0561 ,0596 .0601 ,0599 .0603

.0696 .0790

.0685 .0605 stopped 11 ' stopped

.0645 .05 73

.0662 .0589

1 1

.0528 .0644

.0526 .0641

.0620 .0.583

.06.56 .0574

.0630 .0581

.0632 .0582

6 Avg.

I 8 2 6 2 II 0 3 3 6 .0281 .io357 .0321 .'3310 .0305 .(I294 0335 .0259

.0324 .0246

.0482 .0448

.0458 .0438

.0340 e 0480

.!I340 e 050 1

.0435 .044 7

.0493 .0559

.0554 . .0448

.0550 .0434

.0436 .04 13

.0443 e04 19

.0322. ,034 1

. 0 3 2 3 , .0343

stopped .0765 .0765

.0682 .053 2

.0686 .0557

.0580 .0517

.0680 .0507

11

.0616 .0563

.0622 .0572

.0489 .05 19

.0489 .05 18

.0625 .0473

.0626 .0476

.0596 .0595

.0583 .0.555 stopped 11 .0706

0699 .0541 .0.558 .0564 .0573

.0635 .0586

.0632 .0585

.0548 .054 1

.0469 .0548

.0319 .0528

.0406 .0543

. .. . . . .. .~. . - .. .~ . . . . . , . . ,._ _ . . ~ . " . . . . . - . . , . . . ... .

Heat No.

FV-70 I 1

I 1

I 1

FV - 19B I 1

I I

I 1

FV-11 I

1 1

I 1

FV - 19A 1 1

FV - 20 I I

~ - 1 7 A I !

I I

I I

FV-71 I I

I 1

1 1

FV-56 1 1

1 1

1 1

FV-57 I 1

I I

1 1

Annea led a t

2050°F 2050 2 150 2 150

2050°F 2050 2 150 2 150

2050°F 2050 2150 2 150

2050°F 2050

2050'F 2050

2050'F 2050 2 150 2 150

2050°F 2050 2 150 2 150

2050'F 2050 2 150 2150

2050°F 2050 2 150 2 150

2050°F 2050 2 150 2 150

--

TABLE A - 3 -- CORROSION RESULTS I N R O I L I N G SO1,UTIONS

of 13M HNO3 -!- .50M HI:

ON SHEET (SIX 24 HOUR PERIODS)

Cprros ion Rate 1.E" c) 1

.0772

.0694

.0689

.0671

. lo26

. 1.020

.0844

.0852

.066 7

.0672

.0532 ,0541

.0407

.0420

.0244

.0236

.0454

.0513

.0973

.0984

.0203

.0211

.0286

.0272

.0627

.0899

.0865

.0655

.0911

.0905

.0893

.0906

.1197

.1200

.1178

.1212

L -- .0652 .0668 .0405 . 0395

.0968

.0959

.07:31 ,0738

.07:11

.07;,3

.025 7

.0267

.0355

.0370

.0398

.0388

.084 1

.0844

.0653

.0655

.032.5

.0337

.0288

.0270

.0692

.0373

.0388

.0732

.0712

.0874

.0884

. 1652

.1645

.0612

.0624

.ob87

3

.0353

.0438

.0526

.0509

.0469

.0466

.0505

.0505

.0330

.0339

.0373

.0385

.0512 - 0533

.039 7

.0387

.066 1

.0671

. l o 6 7 ,1072

,0355 .0371 .0424 .0394

.0668

.0659

.0708

4

.0279

.0285

.0266

.0258

.I3296

.0294

.0347

.0349

.0198

. (3201

.0298

.0307

.0453

.0473

.0636 *

.0615

.0532

.0619

. 1.320

.1326

.039 1 -0408 .0628 .0585

.0925

.0911

.0693

5

.0575

.0589

.0683

.0665

.0604

.0598

.05 76

.0582

.0427

.0434

.!I540

.0558

.0575

.0602

.0322

.0317

.0858

.0936

.0865

.0872

.0379

.0395

.0477

.0446

.0447

.0440

.0363 .0720 ' .0689 .0364

.0844 .0765 .0805

.0812 . 0 733 .0769

.0543 .0483 .0796

. OS55 .0495 .0812

.0728 .0711 .0900

.0729 .0703 .OB98

.1250 s topped stopped

6

.0405

.0415

.0348

.0338

.(I381

.0379 I 0458 .0467

.0299

.0304

.0320

.0329

. O e . i O

.0841

.0526

.0515

.0846

.0918 s E opp ed

1 1

.0586

.0513

.'0516

.0484

.0772

.0758

.0749

.0748

.0496

.0875

.0573 0586

.1089

.1096 stopped .~ .~

.1259 excess ive . weight l o s s end g r a i n a t t a c k

1\17 e 0

.13506 ,125 15 . Oh86 . oLc73

.0621

. (If8 1 9

.0577 0582

.0439 ,0446 .(I38 7 .0398

.0519

.0540

.042 1

.04?0

.0699

.0750

. 09 76

.0982

.0373 e 0373 ,0437 .0409

.0689

.0726 0625 0594

.0759

.073&

.0b94 e 0706

. 1.046 0 1045 .1013 . 1.032

_i-

Heat No.

RV-296 I 1

I 1

I 1

RV-294 1 1

I 1

I 1

RV-29 7 I1

I 1

I 1

N- 79 1 1

1 1 ' I t

GD-44 I 1

1 1

I 1

Annealed a t --

20.50°F 2050 2150 2 150

2050°F 2050 2 150 2 150

2050°F 2050 2 150 2 150

2050°F 2050 2 150 2 150

2050°F 2050 2150 2 150

TABLE A - 3 -- -

Corros ion Rat.e IPM 1

,1139 .1118 .1124 .1125

.LO36

. 1037

. 1105

.lo95

.0014

.0016 fog91 .099 1

.1265

.1257

.0968

.0974

,0943 .0937 .0716 .0725

2

,1111 .lo96 .0705 .0698

. 0 752

. 0 79 2

.1548

.1522

.06 75

.0685

.07:?7

. 0 724

. 1299

. 1305

. 1139

. 1154

.0555

.0554

.0735

.0755

-- 3 4

.0716 I 0596

.0708 .0553

.LO72 .0638

.lo50 .0631

I 0616 .0612 .0764 .0742

* 12.1.5 . 121.9 .1339 .1348

.0605

.Oh05

. 1.063

.lo46

. 1.624

. 1.645

.0661

.0666

. 1206 stopped

.1209

.(I693 .OB93

.0692 ,0903

I 1

.0593 .(I470

.0592 .0467

.0910 .0789

.0933 .0809

5

. 1062

.1075

.0786

.0773

.1104 1108 ,0874 .0866

.0842

.0859

.0885

.0889

stopped

. 1004

.1007

.0555

.0554 a 0623 ,0635

11

.1003 , 0 9 3 1. 0 1011 .0927 .1108 f093h .1106 . os9 7 .i068 0869 .i064 '08 70 . 1039 . !Ob6 . 1.042 e 1,052

.0725 .08&9

.0735 . (3860

.0761. .0894

.0762 .O89 7

stopped . 1257 e 1-257

.09 16 .0936

.0917 .094 1

11

e 0730 .(I641 .0729 .(I639 :0679 .07&2 .0693 .0758

Heat NO.

N-70 II

N-19B II

N-11 11

EV-19A II

N-20 11

N - 1 7 A II

EV-71 11

FV-56 11

N-57 It

W-78 I1

RV-296 II

RV-294 I 1

RV-297 11

FI-79 II

GD-44 I I

E_r

1st

.004 12 ,00466

.00513

.00465

.00338 ,00367

.00392 ,00374

.00350

.00347

.00459 -00446

.00292

.00268

.00430

.00367

.00310

.00374

,00060 .00048

.0044 6

.00432

.00089 -00089

-00380 .00376

.00330

.00406

.00059

.00058

n

2nd

.00282

.00279

.00300

.00296

.00205

.00207

.00262

.00254

.00211 * 00210

.00252 -00254

.00209

.00203

.00253

.00261

.00258

.00304

.00333

.00318

.00566

.00584

.00376

.003 70

.00610

.00658

.00406

.00439

-00292 .00292

1 I pj' p i i l l hl &Jl pEI1

TABLE A-4 -- CORROSION RATES I N BOILING COMPLEX MIXTURE

OF 6M "03 + .4M H2SO4 + .4M NaN03

+ . 3M Fe2(S0$)3 + .OM C r + .OM Hg + .Om PO4

3r d

.00368

.00360

.00309

.00308

.00229

.00241

,00259 .00252

.00218

.00272

.00288

.00287

.00302

.00318

.00263

.00282

.002 74

.00310

.00443

.00449

.00737

.00762

.00577

.00579

.00658

.OO 709

.00509

.00552

.00331

.00330

ON SHEET ANNEALED 2050°F Rates i n Inches per Month

4 t h

.00339

.00329

.00267

.00271

.002 13

.00220

.00233

.00228

.00260

.00263

.00245

.00246

.00286

.00304

.00224

.00242

.00233

.00257

.00500

.00530

. 00 722

.00736

.00678

.00679

.00807

.00863

.00481

.005 12

.00368

.00375

5 th

,0040 1 .00390

.00322

.00326

.00290 -00295

.00277

.00271

-00311 .00317

.00293

.00295

.00345 ~ 00372

.00256

.00275

.00278

.0029 7

.00486

.00522

.00722

.007 36

.006 l l

.00622

.00780

.00521

.004ai

.005 12

.00302

.00319

.

6 th

.00350

.00341

.00287

.00293

.00274

.00277

.00249

.00240

-00292 .00296

.00271

.002 74

.00319

.00346

.00241

.00253

.00249

.00257

.00580

.00629

.00859

.00867

.00566

.00590

.00780

.00825

.00569

.00602

.00331

.00339

7th

.00458

.00396

.00328

.00336

.00342

.00340

.00293

.00287

.00343

.00342

.00308

.002a5

.00363

.00395

.00264

.00268

.00220

.00221

.00637

.00685

.00927 ,00923

.00755

.00784

.00938

.009 69

.00592

.00628

.00375

.00254

8 t h

.00359

.00396

.00326

.00340

.00377

.00256

-00308 .00299

.00354

.00358

.00323 ,00351

.00368

.0040 1

.002 78

.00275

.00280

.00267

.00865

.00923

.00892

.00877

.00957

.00434

.00994

.00015

-00585 .00623

.0049 3

.00513

9 t h

.00401

.0038 7

.00336

.00345

.00386

.003 74

.00314

.00305

.00353 -00355

.00316 00321

.00370 -00403

.00288

.00282

.00302

.00273

.00817

.00845

.00971

.009 64

.00892

.00909

.00681 -00694

.006 19

.00624

.004 70

.00483

10th

.00439

.00434

.00349 ,00353

.00334

.00430

.00342

.00333

.00390

.00394

.00361

.00365

.00389

.00423

.00309

.00289

.00315

.00276

.00885

.00936

,009 14 .00894

.00927

.009 74

.00954

.00961

.0058 1

.00604

.005 18

.00539

Avg.

.0010

.003Z 7

.00333

. 00333 ,00298 .003no

.002@8

.002%A

. oomt

.003115

.003BL

.003U

.00324

.003&3

.00280

.00259

.00271

.002B3

.005Qo

.00588

.00775

.00737

.00642

.00603

.007%3

.005&3

.005115

.005x)

.00353

.003M)

Heat No.

FV-70 I t

EV-19B I t

Fv-11 I t

M-19A I t

Fv-20 tt

FV-17A I t

m-71 $1

FV-$6 I1

Fv-57 I t

Fy-78 v 1.

RV-296 It

RV-294 I t

RV-297 I 1

F-f-79 I t

GD-44 I t

1 s t

.00444

.004 19

.00435

.0039 7

.00355

.00337

.00381

.00411

.00399

.00354

.0043 1

.00388

.00290

.00292

.00449

.00450

.00395

.00433

-00382 .004 10

.00424

.00439

,00452 .00449

.00466

.00444

.00428

.00407

.00359

.00330

2nd

.00368

.00383

-00306 .00291

.00230

.00231

.00352

.00361

.00308

.00292

.00310

.00314

.00303

.00293

.0034 1

.00337

.00315

.00290

.00429

.00437

.00539

.00563

.005 59

.00571

.00536

.PO527

.00426

.00405

.00346

.00342

1 m @~C~AB- CORROSION RATES LN BOILING

OF 6M HNO3 t .4M H2SO4

COMPLEX MIXTURE

+ .4M NaN33

+ .3M Fez ( S o 4 ) 3 + .OM Cr'+ .OD1 Hg + .OM PO4

ON SHEET ANNEALED AT 2150°F

INCHES PENETRATION PER MONTH

3rd

.00338

.00347

.00260 ,0025 7

.00204

.00205

.00291

.00299

.00277

.002 74

.00262

.00271

.0029 5

.00286

.00288

.00286

.00275

.00267

.00378

.00385

-00607 .00659

-0059 1 .00605

.00645

.00633

-00466 .00439

.00327

.00332

4 th

.00455

.0046 1

.00311 -0030 7

.00256

.00262

.00359

.00362

.00373

.0039 1

.00317

.00324

.0038 1

.00370

.00335

.00338

.00307

.00307

.00569

.00558

.00828

.00879

.00812

.00817

-00757 .00?54

.0048?

.00454

.00365

.00371

5 t h

.00371

.00373

.00250

.00249

.00213

.00219

.00288

.00289

.00315

.00339

.00259

.00268

.00305

.00298

.00274

.00268

.00252

.00251

.00472

.00451

.00802

-

.ooa79

.00750

.00759

.00723

. nn9?8

.00454

.0042U

.00303

.00314

6 t h

.00443

.00448

.00289

.00286

.00271

.00281

.00331

.00327

.0039 6

.00411

.00306

.00320

.00405

.00393

.00289

.00288

.0029 7

.00296

.00655

.00628

-00954 . 0 1034

.009 12

.009 14

.00840

.0!?5?5

.00554

.00513

.00348

.00385

7 t h

.00346 -00351

-00230 .00230

.00225 .. 00236

.0034 1 -00332

.00368

.00386

.00282

.00298

.00360

.00361

.00268

.00268

.00263

.00261

.006 72

.00639

.01367

.00856

.ooaai

.ooa46

.00899

.GO843

.01086

.00492

.00351

.00336

8 t h

.00421

.00423

.00278

.00287

.00273

.00287

.00288

.00291:

.00377

.00402

.00281

.00298

.00357

.00331

.00252

.00258

.00261

.00259

.00701

.00671

.01228

.O 1024

.00898

.00901

.00893

.GO902

.00580

.00533

.00375

.003a2

9 t h

.00387

.00390

.00271

.00275

.00273'

.0029 1

.00400

.so394

.0048 1

.00524

.00367

.00388

.0044 1

.00423

.00317 -0030 7

.00331

.00324

.00923

.00876

.01109

.01203

.01105

.01103

.01119

.01i i4

.00574

.0069 1

.00489

.00504

10th

,00404 .00408

.00276

.00280

.00288

.00306

.00388

. vv283

.004 74

.00500

.00358

.00382

.00416

.00412

.00313

.00311

.00348

.00334

.00853

.00783

.OL111

.01184

.01061

. 0 1054

nn 7

.oioa4

.01102

.00741

.006a2

.00488

.00499

A v g .

.00398

.00400

.0029 1

.00286

.00259 -00266

.00342

.GO345

.00377

.00387

.00317

.00325

.00355

.00346

-00313 .00311

.00304

.00302

.00603

.00584

.0089?

.008 72

.00802 -0080 7

.00791

.00787

.005ao

.00504

.00375

.00380

Heat No.

FV70-15

FV19 -1 5B

F V l 1 - A

FV 19 - 1 5 A

FV20-15

FV 17- 15A

JW71-15

Temp., 'E

2050

2 150

2300

2050

2150

2300

2050

2150

2300

2050

2150

2300

2050

2 150

2300

2050

2150

2300

2050

2150

2300

COIC3OSION RATES I N - ( d ) B O I L I N G 65X N I T R I C A C I D (FIVE 48 HOUK PERIODS) ( e ) .SM H2S04 AT 200°F ( 2 HOWS) ( f ) 6% FeC13 PITTING TEST

ON SHEET

1st

.0002 3

.00021

.00046

.00045

.00034

.00034

.00043

.00043

.00027

.00024

.00031

.00035

.00035

.00038

.00022

.00023

.00022

.00021

.00027

.00029 -00034 .00031 .00035 .00037

.00035

.00041

.00037

.00037

.00036

.00035

.00040

.00045

.00034

.00038 -00035 .GO034

.00032

.00032

.00037

.00028

.00038

.00039

2nd

.00018

.00017

.00026

.00025

.00025

.00024

.00025

.00034 . 000 19

.00019

.00020 -00016

.00026

.00027

.00017

.00017

.00018

.00017

.00019

.00020

.00028

.00028

.00028

.00028

.00021

.00022

.00020 ,0002 1 .00023 .00023

.00028

.00028

.0002 7

.00030

.00023

.00023

.00021

.00020

.00028

.00016

.00026

.00029

3r d

.00015

.00015

.00021

.00021

.00022 ,00021

.00036

.00035 . 000 14

. 000 14

.00020

.OOO 18

..00021 .00021 .00032 .00015 .00016 .00017

.00017 ,00016 ,00029 .00028 .00030 .00029

.00016

.00018

.00017

.00017

.00016

.00016

.00023

.00023 ,0002 1 .00023 .00019 . ouozo

.00017

.00017

.00021

.00016

.00017

.0002 1

4 t h

.00017

.00017 * 00022 .00022 .00022 .00023

.00037 ,00035 . 000 18 .00018 .00023 .00023

.00023

.00024-

. 000 19 . 000 19

.00018

.00018

.00018

.00018

.00033

.00034

.00035 ,00034

. 000 18 . 000 19

.00017

. 000 19 -00018 .00018

.00027

.00028

.00024

.00026

.00023

.00025

.00017

.00018

.00032

.00017

. 000 19 ,00024

5th

.00017 -00017 .00021 . 000 20 .00023 .00023

.00035

.00035 . 000 18

.00018

.0002s

.00025

.00021

.00023

.00018

.00019

. 000 19

.00019

.00020

.00020

.00034

.00035

.00035

.00034

. 000 15

.00017

. 000 14

. 000 14

.00016 . 000 15,

.00028

.00030 -00026 .00027 .00023 .00024

.00015

.00017 ' .00018

.00013

.00015

. 000 15

Avg. of 5

.00018

.00017

.00027

.00027 '. 00025 .00025

.00037 -00036 -000 19 . 000 19 .00023 .00024

.00025

.0002 7

.00022

. 000 19 . 000 19 -00018

.00020

.00021

.00032 -

.00032

.00033

.00032

.0002 1

.00023

.00021

.00022

.00022

.0002 1

.00029

.00031

.00026

.00029

.00025

.00025

.00020 ,0002 1 .00027 .00018 .00023 .00026

Average- of L 3 , 4 , 5

.00017

.00017

.00023

.00022

.00023

.00023

.00033 -00035 .00017 .00017 .00022 .00021

.00023

.00024

.00022

.00017 . 000 18

.00018

. 000 19

.00019

.00031

.00031

.00032

.00031

.00018 ,00021 .00017 .OOO 18 .00018 .00018

.0002 7

.00027

.00025

.00027

.00022

.00023

. 000 18

.00018

.00025

.00015

.00019

.SM H2S04 2 h r s - 200°F

.42 in/mo

.023 in/mo

.71 i d m o

.ZO inlmo

.IO inlmo

.28 i d m o

.22 inlmo

.30 inlmo

.32 i d m o

.23 in/mo

.26 in/mo

-26 inlmo

.14 in/mo

.26 inlmo

.25 inlmo

. l o inlmo

. 1 7 in/mo

. I7 injmo

.33 inlmo

.32 inlmo

.24 i n l n o

6% PeC13 Room Temperature

. P i t t e d 24 h r s

P i t t e d 24 h r s

P i t t e d 24 h r s

N o p i t s 300 h r s

N o p i t s 300 h r s

N o p i t s 300 hrs

N o p i t s 300 h r s

N o p i t s 300 h r s

N o p i t s 300 h r s

No p i t s 300 hrs

No p i t s 300 h r s

N o p i t s 300 h r s

P i t t e d 100 h r s

P i t t e d 100 h r s

P i t t e d 100 h r s

No p i t s 300 h r s

No p i t s 300 h r s

Nn p i t . 30s hrs

P i t t e d 100 h r s

P i t t e d 100 h r s

Pitted 300 h r s

p e a t No.

M56-15

W57-15

Ff-78

"-296

RV-294

RV-297

FY-79

a-44

- TABLE A-6 ( con td )

65% "03 IPM

Temp. , O F

2050

2150

2300

2050

2150

2300

2050

2 150

2300

2050

2150

2300

2050

2150

2300

2050

2150

2300

2050

2 150

2300

2050

2150

2300

1st

.00040

.00045

.0004 7

.00045

.00053

.00052

.00033

.00031

.00036

.00038

.00039

.00040

.00050

.00033

.00048 :00042 .00044 .00036

.00032

.00031

.00042

.00037 -00041 .00042

.00050

.00045

.00043

.00039

.00038

.00045

fOOO34 .00036 .00044 .OW49 . o o w .OO04 1

.00037

.00036

.00048

.00051

.00044 i m.04 2

.OW24

.00029

.00027

.00031

.00031

.00031

2nd

.00026

.00027

.00025

.00026

.00030

.00029

.00025

.00022

.00027

.0002 7

.00028

.00027

.00015

.0002 7

.00028

.0002P

.00032

.Om31

.00025

.00026

.00032

.00026

.00035

.00034

00033 .00033 .00032 .00031 .00029 .00033

.0002 7 ,00026 .00030 .00032 .00039 .00037

.00028

.00027

.00029

.OO032

.00030

.e0029

.00026

.00024 ,00020 .00022 ,00026 .00027

3rd

.00022

.00023

.00026

.00023

.00016

.00016

.00012

.00014

.00019

.om19

.00021

.00022

.00021

.00017

.00025

.00026 ,00032 .00029

.00022

.00024

.00030

.00026

.00033

.00034

.Oil024

.00025

.00026

.00026 ,00028 .00029

.00020

.00019

.00027

.00029

.00032

.00031

.00026

.00027

.00027

.00028

.00029

.00028

.00021

.00023 I00022 ,00023 ,00024 .00024

4 t h

.00023

.00024

.00025

.00024

.00026

.00026

.00023

.00523

.00026

.00024

.00023

.00024

.00025

.00023

.00024

.00024

.00027 '. 00029 .00022 .OW24 .0002 7 .00024 .00030 .00030

.00024

.00027

.00026

.00026

.00024 ,00026

.00022

.00023

.00025

.00027

.00030

.00030

.00029

.00026

.00028

.00029

.0002 7

.GOO26

.0002 1

.00024

.00026

.00026 ,00029 .00024

5 t h

.00021

.00020

.00020

.00020

.00020

.00019

.00019

.00019

.00018

.00021

.00019

.00020

.00021

.0002 1

.00025

.COO25

.00032

.00025

.00021

.00022

.00029

.00025

.00029

.00030

.00024

.00026

.00025

.00026

.00025

.00026

.00024

.00023

.00024

.00027 -00031 .00031

.00029

.00030

.00029

.00031

.00027

.GOO27

.00021

.00024

.00026

.00026

.00029

.0002 7

Avg. of 5

.00026

.00028

.00029

.00028

.00029

.00028

.00022

.00022

.00025

.00026

.00026

.OW27

.00025

.00024

.00030

. m32;

.00033

.00029

-00024 .00025 .00032 .00028 .00034 .00034

.00031

.00030

.00030

.00028

.00029

.00032

.00025

.00025

.00030

.00033 ,00035

. .00034

,00028 .00029 .00030 ,00034 .00029 .00030

.00023

.00025

.00024

.00026

.00028

.00027

Average of 2, 3, 4, 5

.00023

.00024

.00024

.00023

.00023

.00023

.00020

.00020

.00023

.00023

.00023

.00023

.00021

.ow22

.00026 . GOO26

.00031

.00028

.OO023 -00024 .00030 .OO025 .00032 .00032

.00026

.00026

.00027

.00027

.00027

.00029

.00023

.00023

.00027

.00029

.00033

.00032

.00028

.00028

.O0O2P2

.00030 ,00028 .OUO28

.00024 ,00024 .00024 .00024 .00027 .OW26

.5M &SO4 2 h r s - 200°F

.16 i n h o

.08 inlmo

.18 in/mo

.23 inlmo

.30 in/mo

.23 in/mo

.35 inlmo

.34 inlmo

.34 in/mo

.34 inimo

.36 inlmo

.37 in/mo

.26 in/mo -24 h / m o .23 inlmo .25 inlmo .23 in/mo .23 in/mo

.36 in/mo

.39 inlmo

.28 in/mo

.28 in/mo

.48 in/mo

.42 inlmo

.17 in/mo

.15 inlmo

.21 in/mo

.21 i d m o

.25 in/mo

.25 i n l m o

.26 inlmo

.27 infmo

.26 in/mo

.26 in/mo

.29 i d m o

.28 in/mo

.27 inlmo

.27 inlmo

.29 i n l m o -28 inlolo . 14 injmo .14 Lnlmo

67. FeCl3 Rocrin Temp e ra t ure

No p i t s 300 h r s

P i t t e d 24 h r s

P i t t e d LOO h r s

No p i t s 300 h r s

No p i t s 300 h r s

No p i t s 300 h r s

P i t t e d 56 h r s P i t t e d 144 hrs P i t t e d 168 h r s P i t t e d 168 hrs P i t t e d 144 hrs P i t t e d 144 h r s

P i t t e d 168 hrs P i t t e d 168 h r s P i t t e d 144 h r s P i t t e d 192 h r s P i t t e d 24 hrs P i t t e d 24 hrs

P i t t e d 144 hrs P i t t e d 144 h r s P i t t e d 144 h r s P i t t e d 144 h r s P i t t e d 48 h r s P i t t e d 48 hrs

P i t t e d 168 h r s P i t t e d 168 h r s P i t t e d 144 h r s P i t t e d 144 h r s P i t t e d 24 h r s P i t t e d -24 h r s

OK 300 h r s OK 300 h r a OK 300 h r s OK 300 h r s OK 300 h r s OK 300 h r s

OK 300 h r s OK 300 h r s OK 300 h r s OK 300 h r s OK 300 h r s OK 300 h r s

Heat No.

FV-70

FV-19B

FV-11

FV-19A

Fv-20 I

FV-17A

FV-71

FV-56

Fv-57

FY - 78

RV-296

RV-294

RV-297

FY-79

GD-44

TF.BLE A - 7

B O I L I N G 65% N I T R I C ACID RESULTS

ON S H E E T SAMPLEIS SENSITIZED 1 HOUR AT 1200'F

1~1c.h.e~ P e r Month 1st

.00052

. 00 140

.00082

.0004 1

.00038

.00040

.00049

.00040

.00037

.00044

.0004 1

.00048

.00040

.00042

. 000 58

.00072

.00050

.00051

.00070

.00066

.00086

.00035

.00040

.00044

.00046

.00073

.00043

.00045

.00032

.0003 1

-- 2 nd -- ,00061 .00071

.00039

.00039

.00034

.00036

.00044

.00040

.00037

.00043

.00042

.00044

.00036

.00041

.00046

.00049

.00045

.00044

.00049

.00050

.00054

.00045

.00040

.00044

.00046

.00055

.00043

.00045

.00032

.0003 1

3r d

.00050

.00056

. 00033

.00030

.00030

.00032

.00033

.00068

.00030

.00030

.00036

.00035

.00031

.00035

.00035

.00039

.00035

.00033

.00039

.0004 1

.00045

.OO05 5

.00036

-__I_

. 00036

.00037

.00038

00033 .00033

.00025

.00023

4th

.0005 1 e 00058

.00036

.00034

e 00031 .00031

.00046

.00026

.00030

.00032

.00032

.00033

.00032

.00036

.00036

.00037

.00034

.00034

.00036

.00037

.00040

.0002 i

.00034

.00037

.00038

.00040

.00036

.00037

.00029

.00027

5t:h

.00052 00058

.00034 ,00032

.00034

.00036

.0004 1

.0002 1

.00031

.00033

.00036

.00036

.00033

.00038

.00037

.00039

.00038

.00036

.00036

.00037

.00040

.00036

e 00035 .00037

.00035

.00038

.00037

.00037

.00028

.00027

Avg

.00053

. 000 7 7

.00045

.00035

.00033

.00035

.00043

.00039

.00033

.00036

.00037

.00039

.00034

.00038

.00043

.0004 7

.00040

.00040

.00046

.00046

.00053 ,00038

.00037

.00040

..00040

.00049

.00038

.00039

.00029

.00028

Heat No.

FV-70

FV-19B

Fv-11

FV-19A

Fv-20

FV-17A

FV-71

FV-56

Fv-57

FY- 78

RV-296

RV-294

RV-29 7

FY-79

GD-44

FV-17B

I

1s t

.0208

.0161

.0113

.0167

.0113

.0233

.0280

.0371

.0303

.0432

,0420

.0433

.0383

.0493

6 0190

.0160

TABLE B-1 -- CORROSION RESULTS I N B O I L I N G

OF 13N "03 -t .075M

s OLUTIONS

HF

ON AS WELDED PLATE

Inches P e n e t r a t i o n per Month

2nd

.029 7

.0294

,0211

.0266

.0077

.0191

.0258

.0298

.0282

.0399

.0382

.0363

.0322

,0789

.0285

.0233

3 r d

.02.27

.0207

. 0 144

.021+6

.0177

.0376

.0301

.0331

.024 1

.0284

.0269

.0352

.031.6

.0782

.0286

.0257

-- 4 t h

.0275

.0256

.0161

.0243

.0136

.0290

.0224

.0212

.0295

.0429

.0353

.0396

.0353

s topped

.0292

.0260

5 t h

.0217

.0218

.0211

.0239

. i l l65

.0349

.0219

.0310

.0236

.0364

.0370

.0404

.0332

stopped

.0266

.0231

6 t h

.0290

.0252

.0169

.0169

.0194

.0348

.0260

.0258

.0231

.0343

.036 7

.0351

.0342

stopped

.0268

.0264

Avg .

.0252

.0233

.0168

.0222

. 0 144

.0298

.0257'.

.029 7

.0265

.0375 '

.0361

.0383

.0341

.0688

.0265

.0235

Heat N o .

FV-70

FV- 1 9 B

FV-11

FV - 19A

Fv-20

FV-17A

??I!-71

FV-56

Fv-57

FY- 78

RV-296

RV-294

R V - 2 9 7

FY-79

GD-44

FV-17B

I

1 s t

.0579

.0783

.0427

.0419

.0407

.0846

.0492

.0515

.0510

,0635

.0901

.0735

,0719

.1182

.0493

.0416

-- TABLE B - 2

CORROSION RESULTS I N B O I L I N G SOLUTIONS

OF L;3M #No3 + .25M HF

ON AS WELDED PLATE

Inches P e n e t r a t i o n per Month

2nd -- 3rd 4 t h 5 th 6 t h

.0590 .0460 .0616 .0530 .0486

.0459 .04C19 .0597 .0579 .0528

.0547 .0409 .0449 .0447 .0437

.0352 .0420 .0436 .0342 .0390

.0249 .0343 .0352 .0418 .0355

.0579 .0685 .0809 .0707 .0649

.0408 .0390 .0356 .0438 .0435

.0661 .0442 .0700 .0677 .0556

.0500 .0476 .0572 .0542 * .0401

.0647 .0655 .0992 .0735 * .0680

.09 19 .060.5 .0949 .0756 .0780

.0615 .0540 .0946 .0574 .0662

- 0 5 18 .0739 .0669 .0725 .0800

9

stopped - weld a t t a c k

.0457 .0420 ,049 7 ,0384 .0531

.0720 .0465 .0580 .0788 .0570

Avg.

.0544

.0559

.0453

.0393 '

.0354

.0713

.0420

.0592

.0500

.0724

.0818

.0679

.0695

.0464

.0590

Heat lo e -- Fv-71

FV-17B

Fv - 19A

GD-44

RV-294 I

N - 7 9

FV-70

FV - 19B

RV-297

RV-296

Fv-11

N-78

FY-17A

FY-57

Fv-20

FV-56

1st

.0845

.0909

.0936

.0860

.1579

.1663

.0762

. l o 2 5

.1256

.1357

.0696

.1395

.1269

. l o30

.0755

. l o 6 5

-- TABLE E-3

CORROSION RESULTS I N B O I L I N G S O L U T I O N S

OF 1:3M wN03 4- .50M HP

ON AS WELDED PIA,TE

Inches Pene t r a t ion Per Month

2nd

.0958

.1302

. l o 6 7

. l o 2 3

.1609

.2307

.0928

. l o68

.1308

.1355

.os10

e1198

.1305

. l o o 0

.0854

.1143

3rd

.0945

.1645

--

.0932

. 1066

.1686

.1809

.0943

.0954

.1394

.2170

.0472

. lo14

.0900

.069!3

.04 79

.04 74

a t t a c k

.0461

.0593

.0766

.0696

.OS66

.0926

4 t h 5 t h 6 t h Avg.

“1040 .0513 .0787 .0848

. l o60 s topped-severe ly .1229 a t t acked a t weld end g r a i n a t t a c k

.0696 .0707 .0904 0874

. l o27 .0735 .0826 .0923

.09 73 .0996 .2095 .1490

s topped-weld s e v e r e l y .1926 a t tacked-severe end g r a i n

. 0 744 .1135 .0829

e 1042 s topped- .0936 p i t t i n g type a t t a c k on weld-at tack a t ca rb ide p r e c i p i t a t i o n a r e a s - seve re end g r a i n a t t a c k

.1239 .1364 , 1 2 2 1

.1161 .1259 .1333

s t o p p e d - p i t t i n g .0711 type a t t a c k on w e Id - s ever e a t t ac k a t c a r b i d e p r e c i p i- t a t i o n areas

.1652 .1135 .1220

s topp ed-weld a t t acked- .1158 s p o t t y end g r a i n a t t a c k

.09 72 I 0855 .0931 .09 15

0642 .0941 .0867 .0756

. l o 2 3 .0760 .09 70 .0906

Fea t N O .

EY-70

IFV-19R

FI - 1 14,

FV - 19A

PV-20

EV-17A

FV-71

FV-56

FV-57

~ I _

FY- 78

RV-296

RV-294

RV-297

FY ._ 79

GD-44

FV-17B

1st

- 00375

.00371

.00?.91!

.00323

00043

.00338

.00052

.00304

.00298

. 000 76

. 000 74

.00079

.00074

.00069

.0039 1

.00290

2g.d

00409

.00360

nn3q7

.00321

D 00224

e 00334

.0326 1

.00318

.00306

.00430

.0038 7

.00382

.00417

,00393

.00383

.00298

0 L ."L . - ' ,

a &7 a &--J m; mi a: TABLE B-4 _c_-

CORROSION RATES IN BOILING COP.IPLEX MIXTURE

OF 6M " 0 3 -k .4M ~ 2 S 0 4 -t- .4M NaN03

-1- . 3 M Fe2 (SO/i)3 i- .01M C r -t- . O l M Hg -k .01M PO/,

ON AS WELDED PLATE

Irllches Penetration Per Month

3r d

- 00436

.(I0367

,00236

.0@29 8

.0029 2

.@0312

00353

.00295

.00246

.00143

,00468

,00459

.00460

.0@425

.00340

.00317

-- 4 th

.0049 1

.00376

.00309

.0030F!

. OQ333

.00325

.00365

.00298

.00291

.00889

.00526

.005 1.1

.0054 1

. 00 508

.00350

.00360

5Lh

.00358

- 00322

* 00294

00271

.00300

,00388

00351

e 00247

.00249

.00415

.00430

.00452

.00410

.00438

.00323

.00331

6 t.h

.004 64

.003??

-.-

nn-nn . VV3031

,003 14

.0035 7

.00322

.00330

00262.

.OO29 3

,0046 1

.005 13

.00315

.00513

.00396

.0@342

.0037 7

7 t h

.00460

.00361.

-.-

A n C. n r. uv303

.0030?

00377

a 00317

.00L13

002.42

.@0262

.00524

.00600

.00.541

.0@589

.00506

.Oil351

.00369

8 t h

.00523

.@(I418

.GO465

.00351

.00480

.00362

* 00538

.00271

.00318

.0068Lt

. 00 740

.00717

.0074 1

.00634

.00413

.004 13

9 th.

.00541

.O04 1.8

.00504

.On361

.004 69

.00387

.0051.6

.0026 1

.0@336

.00636

.00662

.006 75

.00679

.00571

.004 13

.00350

10,h

.01)509

.00425

. 0 0 5 i l

--

09164

.00%2

.0037 7

00546 7

,0026 1

.00335

.00@5

.00710

.00730

.00761

. oofio9

. OOQO5

.0039 7

Avg >

2 00460

,00379

. WO36.5

.00322

,00342

I @03/14

e 003 75

.00276

-00290

.00494

.00511

,00486

.00519

.00455

-00371

.0@34 7

Heat No.

Fv-70

lW-19B

Fv-11

N - 19A

Fv-20

N-17A

FV-71

N-56

N-57

FI-78

RV-296

RV-294

RV-297

FY- 79

GD-44

FV-17B

CORROSION TESTS ON AS W E L D E D PLATE W

(d) Boi l ing 65% " 0 3 ( f i v e 48-hour periods) (e) .5M H2S04 a t 200°F ( 2 hour period) ( f ) 6% FeC13 ( p i t t i n g t e s t )

65% " 0 3 IPM

1st

.00050

.00058

.00030

.00027

.00026

.00025

.00036

.00035

.00036

.00036

.00034

.00035

.00038

.00036

.00042

.00042

.00028

.00029

.00046

.00042

.00034

.00039

.00044

.00046

.00035

.00032

.00053

.0005 1

.00040

.0004 1

.00027

.00024

2nd

.00040

.00042

.00023

.00021

.00016

.00016.

.00022

.00020

.00027

.00017

.00022

.00023

. 000 17 . 000 16

.00025

.00025

.OOO 18

. 000 19

.00036

.00034

.00028

.00031

.00036

.00034

.00031

.00028

.00036

.00041

.00040

.0004 1

. O O O l B

.00017

3r d

.00026

.00027

.00025

.00026

.00018

.00019

.00023

.00023

.00028 . 000 18

.00023 ,00024

.00020

.00022

,00024 .00037

. 000 18

.OOO 18

.00036

.00034

.0002 7

.00029

.00032

. 000 30

.00028

.0002s

.00034

.00036

.00031

.00033

.00019

. 000 19

4 t h

.00025

.00025

.00021

.00023

.00014

. 0001s

.00017

.00017

.0002 1

.00016

.00024

.00024

.00017

.00022

.00017 I 000 18

.00020

.00020

.00032

.00031

.00025

.00028

.00028

.00029

.00021

. 000 19

.on032

.00038

.00034

.00035

. 000 15

. 000 14

5 t h

.00025

.00026

.00026

.00019

.00018

. 000 18

.00022

.00022

.00029 ,00020

.00022

.00023

.00019

.00019

.00022

.00025

.00017 . 000 18

.00030

.00029

.00025

.00027

.00028

.00027

.00027 -00024

. OOO??

.00036

.00031

.00032

.00021

.00020

Avg .

.00033

.00036

.00025

.00023

. 000 18

.00019

-00024 .00023

. . n m 3 u - - - - -

.0002 1

.00025

.00026

.00022

.00023

.00026

.00029

.00020

.00021

.00036 -00034

.00028 -00031

I . 00034 .00033

.00028 -

.00026

nnnqe . ""VJO

.00040

.00035

.00036

.00020

. 000 19

Avg. Periods 2, 3, 4 , 4- 5

.00029

.00030

.00024

.00022

.00017

.00017

.00021

.00021

.GOO26

.00018

.00023

.00024

.00018

.00020

.00022

.00026

.00018 ' .00019

.00034

.00032

.00026

.00029

.00031

.00030

.00027

.00024 '

.GOO34

.00038

.00034

.00035

.00018

. 000 18

.5M H2s04 2 h r s - 200°F

.81 in/mo

.20 inlmo

.31 in/mo

.22 in/mo

.20 i n l m o

.OB i d m o

.44 in/mo

.17 i d m o

.22 inlmo

.11 in/mo

.69 in/mo

.go in/mo

.62 in/mo

.% inimo

.20 in/mo

.19 in/mo

Time t o Fit S u r f a c e 6% PeC13 Meld - -

9 6 h r s

72 h r s

24 h r s

96 h r s

24 hrs

48 h r s

72 h r s

72 h r s

96 h r s

216 h r s

266 h r s

300 hrs

264 h r s

216 h r s

96 h r s

48 h r s

72 hrs

48 h r s

96 h r s

a2 hrs

5% h r s

22 h r s

96 h r s

&a h r s

a2 hrs

24 hrs

24 hrs

24 h r s

24 h r s

24 h r s

72 h r s

02 h r s

Hee t N o .

FV-70

FV-11

FY- 7 8

RV-296

RV -294

RV-297

FY-79

FV-17B

1 0

TABLE B - 6 -- CORROSION RATES I N B O I L I N G 65% HNO3

ON WELDED PLATE WHICH WAS REANNEALED

AND THEN SENSITIZED AT 1200'F

I n c h e s Per Month 1 s t

.00039

.00032

.00037

.00035

.00036

.00044

.0005 1

.00031

2 nd

.00037

.0003 1

.00033

.00031

,00030

.00036

.00045

.00027

3r d

. 00032

.00032

,00031

.00029

.00029

.00032

.00048

.00022

0- 4 t h

.00033

.00031

.00030

.00026

,00024

,00028

.00052

.00021

-- 5 t h

e 00335

.00036

,00033

.00030

.00029

.00031

.00058

.00022

-- Avg .

.00035

,00032

.00033

.00030

.00030

.00034

.0005 1

.00025

-

I

...

u u

Average Corrosion Rate mils/month

F N W 0 0 0 0 .k I I U

35 Cr-20 N i

30 Cr-25 N i

N i

1.0 s i

FV 56 310 with .03 si

0 with .28 S i

310 with ..33 Mn

with .020 C

310 with . 2 2 Cb

309 with .008 C

309 with .004 c

309 with .OOsc

309 with -026 c

..

E 0 0) H 0 Z

P +3 N 0

. . . . . .. . . . . . . .

Average Corrosion Rate m i Is /month

R I

L

. ..

13

FV 19B 310 with 1.0 S i

?V56 310 wi th - 0 3 S i

'v57 { l o wi th . 2 8 S i

V17A 110 wi th . 3 3 Mn

10 with .020 C

D44 10 wi th .22 Cb

V296 09 w i t h .008 C

19 with .008 C

0

E 0 . rn

. H 0 z

h) 0 lJl

n

--

I

P

Q

u

Average Corros ion Rate m i l s /month

F I- r r N w

P I 0 0

D I I 0

N w 5?- cn 0 0 0 0

r I Y Y 0 I

0 U 0 2 \o 0 0 0 0 0 0 E 0 0 n

r

35 Cr-20 N i ~

30 Cr-25 Ni

FV 70 30 Cr-15 N i

FV 19B 310 wi th 1.0 Si

FV56 310 wi th .03 S i

FV57 310 wi th . 28 S i

FV17A 310 with . 3 3 Mn

FV 19A 310 wi th .020 C

GD44 310 with . 2 2 Cb

RV296 309 with .008 C

RV29 7 309 wi th .008 C

FY 79 309 Cb

c)

8 0. cn w 0 z

M r c n

h, 0 VI 0

0 w

Y

9 P 0

I

Q

R 0

P

Average Corrosion Rate mila /month

I ’ 0 .b Ln m U 00 W 0 e

Y Y D D 0 d

f

0

E X OQ

+ 0

X N rn

c” + i2 z P, z 0 w 4-

r n, N

r H n

,E

. . . . . . . . . . .. -. . . . . . . . . .