Metalurgie - Comparatie Oteluri Termomecanice Cu Cele Conventionale

Comparison of Thermomechanical Rolledwith Conventional Steels

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12.01.2010 Comparison of TM and N-steels

Advantages of TM-steel

• Properties–Analysis–Toughness

• Economics–Processing advantages, Preheating–Reduction of weight

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S 460 NL S 460 ML

acc. EN 10025-3

Auxiliary Data

acc. EN 10025-4

Auxiliary Data

C < 0,20 0,17 < 0,16 0,09 Si < 0,60 0,45 < 0,60 0,30 Mn 1,00 - 1,70 1,65 < 1,70 1,50 P < 0,030 0,015 < 0,030 0,011 S < 0,025 0,010 < 0,025 0,005

Nb < 0,05 - < 0,05 < 0,04 V < 0,20 0,17 < 0,12 < 0,05

Mo < 0,10 - < 0,20 - Ni < 0,80 0,29 < 0,45 0,25 CE 0,50 0,39

Pcm 0,29 0,20 CET 0,34 0,28

Carbon equivalents: CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni+Cu)/15 Pcm = C +Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B CET = C + (Mn + Mo)/10 + (Cr + Cu)/20 + Ni/40

TM Low carbon content

Plate thickness 50 mm

Advantages of TM-steel - Analysis

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a) N b) Q+T

Microstructures for different process routes (exemplary)

c) TM d) TM+ACC

20 µm

20 µm 20 µm

20 µm

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Typical carbon equivalents and microstructures for normalised and thermomechanical rolled steels

100

200

300

400

500

600

700

0,20 0,25 0,30 0,35 0,40 0,45Ceq

min

. YS

in M

Pa

Ceq = C + Mn/6 +(Mo+Cr+V)/5 + (Cu+Ni)/15

normalizedS355N

TMS355M

20 µm

0.20 0.25 0.30 0.35 0.40 0.45

20 µm

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TM High toughness / High safety

-120 -100 -80 -60 -40 -20 0 200

50

100

150

200

250

300

350 S355J2+N S460ML S690QL

Cha

rpy-

V [J

]

Temperature [°C]

Welding leads to

toughness

reduction

High toughnessin the base

material reducesthe risk of brittle

fracture and gives saftey!

Advantages of TM-steel - toughness

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TM Cost efficiency – Low preheating

Advantages of TM-steel - Processing advantages

Low preheating temperatures are not only a matter of costs!Also in terms of job safety, low preheating temperatures are beneficial!

NO HOT SURFACES / NO HANDLING WITH GAS / BETTER WORKING CONDITIONS

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EN 1011-2:Recommendations for arc welding of ferritic steels

( ) 328Q32CET53HD6235dtanh160CET697T 35.0

p −×−×+×+⎟⎠⎞

⎜⎝⎛×+×=

Preheating is necessary to avoid: excessive hardening

Preheating is necessary to avoid: cold cracking

Advantages of TM-steel - Preheating

TM Low carbon content / Low preheating

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EN 1011-2:Recommendations for arc welding of ferritic steels

( ) 328Q32CET53HD6235dtanh160CET697T 35.0

p −×−×+×+⎟⎠⎞

⎜⎝⎛×+×=

Tp - Preheating temperature [°C]CET - Carbon equivalent [%]: CET = C + (Mn + Mo)/10 + (Cr + Cu)/20 + Ni/40d - Plate thickness [mm]HD - Hydrogen content [cm³/100 g]Q - Heat input [kJ/mm]

Preheating is necessary to avoid: excessive hardening

Preheating is necessary to avoid: cold cracking



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0 20 40 60 800

2

4

6

8

10

75°C

50°C

25 °C

typisc he r B ereichfür H2 Geh alte

S355M S460M

Plate thickness [mm]

Hyd

roge

nco

nten

tof w

eldi

ngco

nsum

able

[cm

3 /100

g]H

ydrogencontentof w

eldingconsum

able[cm

3/100g]

0 20 40 6 0 800

2

4

6

8

1 0

100 °C

7 5°C

50 °C

25°C

typisch er B ereichfür H2 Geh alte

Plate thickness [mm]

Calculated with Q = 2.5 kJ/mm (submerged arc welding) and for typical CET´s



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Avoiding

preheating1. No installations

No setting up timeNo gas



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Reducing preheating

temperatures2. Gas consumption ↓

Heating time ↓

Avoiding





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Reducing preheating


Heating time ↓

Avoiding



Biggest potentialfor reducing costs



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Reducing preheating


Heating time ↓

Often underestimated,but worth to think about

Avoiding



Biggest potentialfor reducing costs



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Sauertal Bridge (Germany)

Box-girder-bridgeLength: 1195 mWidth: 27 m11 Spans: 75 – 150 mTonnage: 13,000 tGrade: S355J2+N

3000 t > 25 mm thickness



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Alternative:

S355J2+N > S355MNo preheating

150,000 €C = A - BBENEFIT

75,000 €B = 3,000 x 25 €/tB) Additional costs S355M (25 €/t)

225,000 €A = 30,000 h x 15 % x 50 €/hA) Saving preheating times

Conditions:

30,000 h welding time15 % for preheating50 €/h labour costs



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S355NL

S355ML

changingdeliverycondition

t1

t2

t1 = t2


Advantages of TM-steel - Reduction of weight

Possibility to avoid preheating!• no gas consumption• no set-up times• higher capacity in the work shop

0,2 0,3 0,4 0,5-50

0

50

100

150

200

250

T p C

ET [°

C]

Carbon equivalent CET [%]

EN 1011-2:TpCET = 750 x CET – 1500.01% CET ca. 7.5°C

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TM Cost efficiency – High strength

S460NL

S355NL

increasingyield

strength

t

t

A

A,B ~ t2

Wel

ding

cos

ts

Plate thickness

~ t²

• Weight reduction (ca. 30%)• Bigger assembling units possible• Less holding times in the workshop• Less welding consumables• Reduction of welding time• Reduction of testing time

t1

t2

t2 < t1


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S460NL73 mm

73 mm

S355NL fy = 315 Mpa100 mm

S460ML

increasingyield

strength

changingdeliverycondition

TM Cost efficiency – High strength TM


• Weight reduction (ca. 30%)• Bigger assembling units possible• Less holding times in the workshop• Less welding consumables• Reduction of welding time• Reduction of testing time

• Avoiding/Reducing preheating• Better weldability• High toughness reserves

=> High safety

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Thank youfor your

attention!

Documents

Metalurgie - Comparatie Oteluri Termomecanice Cu Cele Conventionale