Small Punch Creep Tests for Grade 92 Forgings · 2018. 10. 6. · Seven specimens Rwere extracted in the L and directions for the N/T F92 steel. These were compared to seven Q/T specimens

Small Punch Creep Tests for Grade 92 Forgings

ECCC WG 3A report

Kappou, E

Holmström, S

2018

EUR 29360 EN

This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science

and knowledge service. It aims to provide evidence-based scientific support to the European policymaking

process. The scientific output expressed does not imply a policy position of the European Commission. Neither

the European Commission nor any person acting on behalf of the Commission is responsible for the use that

might be made of this publication.

JRC Science Hub

https://ec.europa.eu/jrc

JRC113068

EUR 29360 EN

PDF ISBN 978-92-79-93959-4 ISSN 1831-9424 doi:10.2760/12580

Luxembourg: Publications Office of the European Union, 2018

© European Atomic Energy Community, 2018

Reuse is authorised provided the source is acknowledged. The reuse policy of European Commission documents is regulated by Decision 2011/833/EU (OJ L 330, 14.12.2011, p. 39).

For any use or reproduction of photos or other material that is not under the EU copyright, permission must be

sought directly from the copyright holders.

How to cite this report: Kappou, E. and Holmstrom, S., Small Punch Creep Tests for Grade 92 Forgings, EUR 29360 EN, Publications Office of the European Union, Luxembourg, 2018, ISBN 978-92-79-93959-4, doi:10.2760/12580, JRC113068.

All images © European Atomic Energy Community, 2018 unless otherwise specified

i

Contents

Acknowledgements ................................................................................................ 1

Abstract ............................................................................................................... 2

1 Introduction ...................................................................................................... 3

2 Materials and methods ........................................................................................ 4

2.1 Material and specimens ................................................................................. 4

2.2 Test rig and experimental procedure .............................................................. 5

3 Experimental ...................................................................................................... 7

3.1 Description of testing procedure and methods ................................................. 7

3.2 Results and discussion .................................................................................. 9

2 Conclusions .................................................................................................... 12

References ......................................................................................................... 13

List of figures ...................................................................................................... 14

List of tables ....................................................................................................... 15

Annexes ............................................................................................................. 16

Annex 1. Test curves and top views of tested samples, Q/T F92 ............................ 16

Annex 2. Test curves and top views of tested samples, N/T F92 ............................ 23

1

Acknowledgements

Special thanks to my supervisor Stefan Holmström for his precious help and guidance. I

would also like to thank Matthias Bruchhausen and Stefan Ripplinger for the knowledge

they transmitted to me. Special thanks to Franchini Acciai SpA for the test materials and

material expertise. Support from the ECCC WG1 and WG3A are gratefully acknowledged.

2

Abstract

This report has been prepared for the ECCC WG 3A as an in kind contribution of JRC. The

report compares the creep strengths of two F92 forgings (Grade 92 steel) with differing

heat treatments. The two heat treatments are normalizing and tempering and quenching

and tempering. The comparison is entirely based on small punch creep (SPC) data

analysis. The SPC test samples were extracted from different orientations of the bulk

materials. The calculated equivalent stresses of the tests are converted using the

equations recommended in the soon to be published small punch standard. Also, a new

simplified method of determining the minimum deflection rate and deflection at minimum

deflection rate is described and result in equal creep strength estimates. It is shown that

the quenched and tempered steel is about 30% stronger than the normalized and

tempered forging in short duration creep.

3

1 Introduction

Miniature testing techniques have many uses and are excellent for testing in service

materials, such as nuclear power plants, to support life extension investigations and/or

determining the current material state. The small punch test (SP for "tensile" properties

and SPC for creep properties) is a method for evaluating the mechanical properties of a

material with minimal amount of material causing negligible destructive intrusion on the

components under investigation [1-5]. In the SP tests a thin disc shaped specimen is

manufactured from the bulk material in a specified direction. The SP tests do not only

allow for the evaluation of real components by using materials with limited size, but can

also pin-point critical locations impossible to be targeted by the conventional methods

[5][6]. As for creep, the SPC test is a simple and economical method that has the

potential to for some extent replace the shorter duration conventional uniaxial creep test

[7][8].

The work presented in this report has been performed for the European Creep

Collaborative Committee (ECCC). ECCC has been active as leading European network in

the assessment of high temperature materials for standardisation, pressure equipment

design, and component integrity since 1992. The ECCC was founded as an EU project,

but is now independently governed by European industry as a series of Joint Industrial

Projects (JIP). JRC is a member of the ECCC JIP2 and 3 (2015-2020). JRC is actively

contributing in kind to the network for the Work Groups 1 (general modelling), 3a

(Ferritic steels) and 3b (Austenitic steels). Miniature testing techniques is a sub-work

group under WG1 with a special interest in small punch creep testing (SPC) and the test

results conducted on the ECCC F92 materials is JRC contribution to WG3a. This report is

linked to the two first mentioned WGs.

The main outcome of this report is supporting the validation of the SPC tests for

determining the short term creep properties of steels. Here fourteen SPC tests conducted

on two heavy wall tubular forgings of grade 92 are assessed. The two forgings were

subjected to different heat treatments, namely normalizing & tempering (N/T) and

quenching and tempering (Q/T), respectively (designated as F92).1 The test results are

mainly compared with regard to their equivalent stresses and rupture times.

1 The details of the heat treatments are confidential.

4

2 Materials and methods

2.1 Material and specimens

The small punch ECCC test programme in Work Group 3a (Ferritic steels) was adapted to

support the ongoing standardization work of ECISS / TC101 / WG1 and was extended to

evaluate the differences in creep resistance induced by two heat treatments performed

on forged grade 92 materials. The test programme includes room temperature and high

temperature SP tests for estimating the proof strength (Rp02) and the ultimate tensile

strength (Rm) as well as determining the differences in creep strength. In this report the

emphasis is laid on the creep strength evaluation. In

Table 1, the specimens coming from the two materials under investigation, i.e. F92

forgings produced by FRANCHINI ACCIAI SpA (Mairano, Italy), are presented.

Table 1. The ECCC F92 forgings and their tensile (uniaxial) properties at room temperature.

Test

groups

Heat

treatment

Rp02

(RT)

MPa

Rm

(RT)

MPa

El

(%)

RA

(%) Rp02/Rm

Uniaxial

creep data

CT &

CD

Normalized

and

tempered

(N/T)

470 645 25.4 58 0.73 Assessor only

1)

DA

Quenched

and

tempered

(Q/T)

648 775 21.5 61 0.84

Not

disseminated 2)

1) The uniaxial time to rupture data for the F92 steel is confidential within ECCC 2) Might become available within ECCC

The difference in proof strengths between the two materials shows that the Q/T is

stronger and has higher yield strength. This explains the larger deflections found in the

N/T specimens (for the same force) at loading and during the SPC tests.

The extraction orientation of the small punch test specimens could also have had a small

effect on the properties of the material. The specimens can be extracted from the target

component in different directions as shown in Figure 1. For a pipe type of component L is

the longitudinal direction, R the radial direction and C the circumferential (hoop)

direction. The specimen extraction directions in the test reported here, are given in Table

2 as indicated by the letter R or L appended to the material name. For the assessment

presented here the orientation of the specimen was not taken into account.

5

Figure 1. Orientation of SPT specimens [9].

2.2 Test rig and experimental procedure

In small punch creep (SPC) tests, a cylindrical rod or puncher with a hemispherical tip or

a flat punch combined with a ball is forced through the metal disc shaped specimen. In

the case of SPC the force is constant and the specimen is deformed as a function of time

by creep. The temperature is held constant in the test and the test is continued until the

specimen ruptures. The main test result is the time deflection curve.

The specimen holder consists of two dies that clamps the specimen so that the specimen

cannot bend upwards. At JRC a flat puncher is combined with a 2.5 mm ball. The

receiving hole in the lower die has a diameter of 4 mm with 0.2 mm deep 45 chamfer.

The deflection u is measured from below, via a ceramic rod transferring the movement to

an LVDT. The temperature T is controlled and measured by a calibrated N thermocouple

(TC) integrated in the sample holder touching the inner die. A furnace is heating the test

assembly. During the test argon gas is flowing into the specimen holder to avoid

oxidation. A simplified SPC set-up is shown in Figure 2.

6

Figure 2. Simplified presentation of a small punch test device [2].

7

3 Experimental

3.1 Description of testing procedure and methods

Seven specimens were extracted in the L and R directions for the N/T F92 steel. These

were compared to seven Q/T specimens extracted in the L direction. The specimens were

tested at different forces and temperatures with the aim of estimating the uniaxial creep

strengths of the respective materials. Other mechanical properties such as fracture strain

and reduction of area were also targeted. The assessment on equivalent stress as a

function of time to rupture and creep rate is based on the time-deflection-time curves.

The equivalent stress is calculated from a "force to stress conversion" equation =F/, as

it is described below in Equations 2-3.

A comparison was also conducted between the standard way of calculating the minimum

deflection rate [9] and a new simplified methodology to extract a representative

deflection for equivalent stress calculation. Since there is a strong dependence between

the estimated equivalent stress and the measured deflection at the minimum deflection

rate a robust methodology for extracting it is very important [7].

The calculation of minimum deflection rate (du/dt) from the time-deflection rate curve is

not always an easy issue. The minimum deflection rate is defined as the minimum slope

in the time-deflection curve and traditionally its value can be extracted from the

minimum point in the time-deflection rate curve. The differentiation of "noisy" data can

lead to scatter if sub optimal amount of data points are used for calculating the deflection

rate. The deflection rate versus time curve can cause significant differences in the

location when finding the "minimum" location. Especially for less ductile materials than

for brittle, more scatter has been observed. As a result, it is difficult to determine the

position of the minimum. A not very smooth curve could create problems in the

determination of the deflection. The new method based on the time to rupture could

simplify the conversion of SPC equivalent stress and reduce the scatter for the creep

strength estimation.

According to the new method, instead of finding the minimum deflection rate and the

deflection at minimum deflection rate the alternative deflection and rate are calculated

directly from the time-deflection curve without differentiating. The deflection umin is

replaced by the deflection at ½ life (u1/2) and the minimum deflection rate is the slope

between the deflections at 1/3 and 2/3 of life as given in Equation 1. The simplified

method is shown in Figure 3.

�̇�1/2 = (𝑢2

3−

𝑢1

3 ) (

2𝑡r

3−

1𝑡r

3⁄ ) (1)

8

Figure 3. Prediction of u1/2 and u1/2-rate by using the new method.

After using both methods to determine the deflection at minimum deflection rate values,

the corresponding equivalent stresses are calculated. As incorporated in the new small

punch pre-standard, the most difficult part of using SPC tests for predicting the uniaxial

creep properties is the conversion between the applied force F in a SPC test to the

equivalent uniaxial stress at equal rupture times.

The empirical force to stress (EFS) ratio =F/ that is a fully empirical model based on a

large number of test for multiple materials that have both uniaxial and SPC data

[7][9][10].

The equivalent stresses according to the EFS using the deflection at minimum deflection rate (Ϭumin) and by using the deflection at ½ life (Ϭu1/2), were calculated by Equation 2

and Equation 3 respectively.

1 =𝐹

Ϭumin= 1,920 ∗ 𝑢min

0,6530 (2)

2 =𝐹

Ϭu1/2= 1,920 ∗ 𝑢1/2

0,6530 (3)

For calculating an estimate of the strength factor between the two heat treatments the

Larson-Miller (LM) model was used to include the tests performed at different

temperatures. The Larson-Miller Parameters method (PLM) is based on the Arrhenius

equation and gives the relation between stress, temperature and rupture time [2]. It has

been widely used in life prediction and it is the simplest time-temperature parameter

approach. It has been found that this model works rather well in interpolation and in a

limited range for extrapolations towards shorter test durations [2][7]. The PLM is defined

in Equation 4, where T is temperature given in Celsius (C) and tr the time to rupture in

hours (h). The constant C of the PLM has been optimized earlier for P92 steel [7]. For the

F92 materials the parameter C=32 was used.

9

𝑃𝐿𝑀 =(log(𝑡r)+𝐶)∙(𝑇+273)

1000 (4)

3.2 Results and discussion

In Table 2 the results are given for each SPC test. For each test temperature, force, time

to rupture (tr), minimum deflection rate (min-rate) and deflection at minimum deflection

rate (umin) are given together with the calculated equivalent stress. The values of u1/2-

rate and u1/2 were also calculated, by using the simplified methodology. All test curves

with their extracted values are given as Annexes 1-2. The equivalent stresses were

predicted by using the EFS equations and the PLM calculated for comparing the creep

strengths.

Table 2. SPC test results.

Specimen Material Force (N)

Temperature (

0C)

tr (h) min-rate u1/2-rate umin (mm) u1/2 (mm) Ϭumin (N) Ϭu1/2 (N) PLM (C=32)

CD-050 N/T-L 500 600 26.75 0.016514 0.017068 1.472393 1.467646 202.3 202.7 29.18205

CD-046 N/T-L 550 600 14.78 0.030319 0.031849 1.607512 1.613841 210.1 209.6 28.95713

CD-051 N/T-L 550 600 12.35 0.031517 0.034893 1.509416 1.515745 219 218.3 28.88903

CD-048 N/T-L 600 600 3.61 0.129885 0.135455 1.484101 1.484417 241.5 241.4 28.42270

CT-010 N/T-R 300 650 147.14 0.002424 0.002819 1.351196 1.384739 128.4 126.3 31.53682

CT-006 N/T-R 350 650 56.11 0.006573 0.007687 1.486945 1.478375 140.7 141.2 31.15036

CT-009 N/T-R 500 600 38.27 0.010446 0.011010 1.489164 1.516061 200.8 198.5 29.31784

DA-003 Q/T-L 500 600 96.11 0.002361 0.002598 1.551186 1.575552 195.5 193.5 29.66696

DA-004 Q/T-L 550 600 52.13 0.004561 0.004844 1.198989 1.228102 254.4 250.5 29.43502

DA-008 Q/T-L 600 600 34.09 0.007325 0.008299 1.098994 1.127474 293.8 289.0 29.27398

DA-007 Q/T-L 450 650 12.12 0.037315 0.040968 1.637258 1.656561 169.9 168.6 30.53607

DA-001 Q/T-L 550 650 4.28 0.106064 0.112141 1.431572 1.478722 226.6 221.9 30.11882

DA-002 Q/T-L 350 650 66.62 0.007057 0.007723 1.104370 1.078110 170.8 173.5 31.21921

DA-009 Q/T-L 300 650 197.68 0.001919 0.002123 0.924953 0.947736 164.4 161.8 31.65516

As shown in Annex 2, the test specimen CD-046 was tilted during the tests since the

specimen was not properly centred in the lower die. As a result, the puncher did not

punch the specimen in the centre. Thus, a re-test was conducted at the same

temperature-load conditions (CD-051). The comparison of the results of these two

specimens showed umin and tr values very close to each other. The tilted specimen did not

affect the calculated equivalent stress very much.

The calculated equivalent stresses (Ϭumin) of specimens made from N/T-L and Q/T-L

materials tested in 600OC, are plotted against tr in Figure 4. The equivalent SPC stresses

depend on the SPC test curve. Thus, N/T specimens with higher umin give lower

equivalent stresses at equal applied force. In contrast, the stronger Q/T specimens with

lower umin have higher equivalent stresses compared to the N/T at the same applied

force. The linear fits of Q/T and N/T specimens, respectively, indicate small deviations

from linear behaviour at 600°C.

The Ϭumin of both materials tested at 650OC are also plotted versus tr in Figure 4, though

it is apparent that some of the Q/T don’t fit as well on a linear fit.

10

a) b)

Figure 4. N/T-L and Q/T-L specimens plotted in a tr- Ϭumin plot at a) 600OC, b) 650OC.

The equivalent stresses (Ϭumin) of both N/T and Q/T specimens, for all temperatures, are

plotted against the PLM in Figure 5. The lower equivalent stresses of N/T specimens in

comparison to Q/T can clearly be seen. The Q/T strength is approximately 1.3 times the

N/T strength.

Unexpectedly, two of the Q/T specimens showed similar behaviour as the N/T material.

The specimen DA-007 and DA-003 showed lower equivalent stresses, similar to N/T

specimens. The discrepancy may be due to the large umin measured in these tests. A

possible source of error is the offset of the LVDT at loading.

In order to check this, the deflection at the beginning of the test, u0 (see Figure 3), i.e.

deflection after loading was extracted. The u0, was also extracted for the test at the same

temperature and a higher load. Thus, the u0 of DA-003 has been compared with the u0 of

"normally" behaving DA-004 as given in Table 3. Despite the 50 N higher force for DA-

004 than DA-003 it had a higher u0 value. This finding can indicate inaccuracy of LVDT

signal at loading for the outlier DA-003. Similarly, the u0 of DA-007 was compared with

the u0 of DA-001 with similar outcome.

Figure 5. The Larson-Miller fitting results of both N/T and Q/T specimens. The blue arrows indicate the specimens that showed large u0 values.

y = -1.5393x + 341.48R² = 0.9851

y = -1.0755x + 235.31R² = 0.7649

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120

Ϭumin

tr

Q/T-L

N/T-L

600

y = -0.1851x + 195.93R² = 0.3197

y = -0.1353x + 148.28R² = 1

0

50

100

150

200

250

0 50 100 150 200 250

Ϭumin

tr

Q/T-L

N/T-L

650

y = -45.38x + 1584.5R² = 0.6955

y = -34.784x + 1223.6R² = 0.9905

0

50

100

150

200

250

300

350

28 28.5 29 29.5 30 30.5 31 31.5 32

Equ

ival

en

t st

ress

Larson-Miller/1000, C=32

Q/T

N/T

11

Table 3. u0 of Q/T specimens that showed unexpected deflections (marked with *) and the tests

that were compared for deflection at loading.

Specimen Force (N) Temperature (0C) U0 (mm)

DA-003* 500 600 0.87

DA-004 550 600 0.57

DA-007* 450 650 0.77

DA-001 550 650 0.78

The higher tensile strength and higher yield of the Q/T material can also explain their

lower values of minimum deflection rate for the rather short tests.

With the aim of comparing the standard and the new simplified assessment method the

equivalent stresses of all tests were plotted against each other. The same was done for

the minimum deflection rate. Figure 6 shows the correlations between the determined

test results. The two calculated slopes and the R-squared values are very close to unity,

indicating that both methods give the same predictions.

a) b)

Figure 6. N/T and Q/T specimens plotted together in a a) Ϭu1/2 versus Ϭumin chart, b)

u1/2-rate versus umin-rate.

y = 0.9917xR² = 0.9979

0

50

100

150

200

250

300

350

0 50 100 150 200 250 300 350

Ϭumin

Ϭu1/2

y = 0.9808xR² = 0.9994

-3

-2.5

-2

-1.5

-1

-0.5

0

-3 -2.5 -2 -1.5 -1 -0.5 0

log

(min

-rat

e)

log (u1/2-rate)

12

2 Conclusions

In this report the two heat treatments of F92 forgings have been compared for their

creep strengths and deflection rates. The main conclusions are;

The Q/T material is about 30% stronger than the N/T in short term creep.

The softer N/T material has higher deflections at minimum deflection rate causing

lower equivalent stresses at equal force than the Q/T material.

The new simplified method of predicting the minimum deflection rate and the

deflection at minimum deflection rate give the same results as the more scatter

prone standard methodology.

A tilted specimen did not affect the calculated equivalent stress and not the time

to rupture.

13

References

[1] M. Bruchhausen, S. Holmström, I. Simonovski, T. Austin, J.-M.

LapetiteS.Ripplinger, F. de Haan, “Recent developments in small punch testing:

Tensile properties and DBTT”, Theoretical and Applied Fracture Mechanics, vol.

86, pp. 2-10, 2016.

[2] M. Bruchhausen, S. Holmström, J.-M. Lapetite, S. Ripplinger, “On the

determination of the ductile to brittle transition temperature from small punch

tests on Grade 91 ferritic-martensitic steel”, International Journal of Pressure

Vessels and Piping, 2017.

[3] C. Wen, T. Xu, K. Guan, “Correlation Factor Study of Small Punch Creep Test

and Its Life Prediction”, Materials, vol. 9, Issue 10, 2016.

[4] Y. Zheng, S. Yang, X. Ling, “Creep life prediction of small punch creep testing

specimens for service-exposed Cr5Mo using the theta-projection method”,

Engineering Failure Analysis, 2016.

[5] P. Dymáček, “Recent developments in small punch testing: Applications at

elevated temperatures”, Theoretical and Applied Fracture Mechanics, 2016.

[6] D. Andrés, R. Lacalle, and J. A. Álvarez, “Creep property evaluation of light

alloys by means of the Small Punch test: Creep master curves,” Materials &

Design, vol. 96, pp. 122–130, 2016.

[7] S. P. Jeffs, R. J. Lancaster, and T. E. Garcia, “Creep lifing methodologies applied

to a single crystal superalloy by use of small scale test techniques,” Materials

Science and Engineering: A, vol. 636, pp. 529–535, 2015.

[8] S. Holmström, Y. Li P. Dymacek, E. Vacchieri, S.P. Jeffs, R.J. Lancaster, D.

Omacht, Z. Kubon, E. Anelli, J. Rantala, A. Tonti, S. Komazaki, Naveena, M.

Bruchhausen, R.C. Hurst, P. Hähner, M. Richardson, D. Andres, “Creep strength

and minimum strain rate estimation from Small Punch Creep tests”, Mater. Sci.

Eng. A, vol. 731, pp. 161–172, 2018.

[9] S. Yang, X. Ling, Y. Zheng, “Creep behaviors evaluation of Incoloy 800H by

small punch creep test”, Mater. Sci. Eng. A, vol. 685, pp. 1-6, 2017.

[10] ECISS/TC 101-prestandard, “Metallic materials - Small punch test

method”, 2017.

[11] F. Dobeš, P. Dymáček, “Fracture-based correlation of uniaxial and small

punch creep data”, Theor. App. Fra. Mec., 2016.

https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!https://www.sciencedirect.com/science/article/pii/S0167844216301677?via%3Dihub#!

14

List of figures

Figure 1. Orientation of SPT specimens [9]. .............................................................. 5

Figure 2. Simplified presentation of a small punch test device [2]. ............................... 6

Figure 3. Prediction of u1/2 and u1/2-rate by using the new method. .............................. 8

Figure 4. N/T-L and Q/T-L specimens plotted in a tr- Ϭumin plot at a) 600OC, b) 650OC. .10

Figure 5. The Larson-Miller fitting results of both N/T and Q/T specimens. The blue

arrows indicate the specimens that showed large u0 values. .......................................10

Figure 6. N/T and Q/T specimens plotted together in a a) Ϭu1/2 versus Ϭumin chart, b) u1/2-

rate versus umin-rate. ............................................................................................11

15

List of tables

Table 1. The ECCC F92 forgings and their tensile (uniaxial) properties at room

temperature. ........................................................................................................ 4

Table 2. Results of tested specimens. ....................................................................... 9

Table 3. u0 of Q/T specimens that showed unexpected deflections (marked with *) and

the tests that were compared for deflection at loading. .............................................11

16

Annexes

Annex 1. Test curves and top views of tested samples, Q/T F92

Sample: F92 DA-001 (650OC, 550N)

F92 DA-001 (650

OC, 550N)

T=650OC

F=550N

DA-001

RUPTURE TIME

MIN DEFLECTION RATE

TIME AT MIN DEFLECTION

RATE

DEFLECTION AT MIN

DEFLECTION RATE

4.28h 0.106mm/h 1.695h 1.431mm

Time-deflection curve & Time-deflection rate curve (T=650OC F=550N)

0.1

1

10

100

1000

10000

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)

deflection (mm) deflection rate (mm/h)

17

Sample: F92 DA-002 (650OC, 350N)

F92 DA-002 (650OC, 350N)

T=650OC

F=350N

DA-002

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

66.62h 0.007mm/h 36.43h 1.104mm


0.001

0.01

0.1

1

10

100

1000

10000

100000

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50 60 70

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


18

Sample: F92 DA-003 (600OC, 500N)

F92 DA-003 (600OC, 500N)

T=600OC

F=500N

DA-003

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

96.11h 0.0024mm/h 38.15h 1.551mm


0.001

0.01

0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 20 40 60 80 100 120

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


19

Sample: F92 DA-004 (600OC, 550N)

F92 DA-004 (600OC, 550N)

T=600OC

F=550N

DA-004

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

52.13h 0.0046mm/h 19.32h 1.198mm


0.001

0.01

0.1

1

10

100

1000

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 10 20 30 40 50 60

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


20

Sample: F92 DA-007 (650OC, 450N)

F92 DA-007 (650OC, 450N)

T=650OC

F=450N

DA-007

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

12.12h 0.037mm/h 5.548h 1.656mm

Time-deflection curve & Time-deflection rate (T=650

OC F=450N)

0.01

0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12 14

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


21

Sample: F92 DA-008 (600OC, 600N)

F92 DA-008 (600OC, 600N)

T=600OC

F=600N

DA-008

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

34.09h 0.007mm/h 13.30h 1.098mm


OC F=600N)

0.001

0.01

0.1

1

10

100

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 5 10 15 20 25 30 35 40

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


22

Sample: F92 DA-009 (650OC, 300N)

F92 DA-009 (650OC, 300N)

T=650OC

F=300N

DA-009

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

197.7h 0.002mm/h 86.98h 0.925mm


OC F=300N)

0.001

0.01

0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 50 100 150 200 250

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


23

Annex 2. Test curves and top views of tested samples, N/T F92

Annex 2A. N/T-L samples

Sample: F92 CD-050 (600OC, 500N)

F92 CD-050 (600

OC, 500N)

T=600OC

F=500N

CD-050

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

26.75h 0.016mm/h 13.51h 1.472mm

Time-deflection curve & Time-deflection rate (T=600OC F=500N

0.01

0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 5 10 15 20 25 30

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


24

Sample: F92 CD-046 (600OC, 550N)

F92 CD-046 (600OC, 550N)

T=600OC

F=550N

CD-046

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

14.78h 0.030mm/h 7.109h 1.607mm

Time-deflection curve & Time-deflection rate (T=600OC F=550N)

0.01

0.1

1

10

100

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12 14 16

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


25

Sample: F92 CD-051 (600OC, 550N)

F92 CD-051 (600OC, 550N)

T=600OC

F=550N

CD-051

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

12.35h 0.031mm/h 5.988h 1.509mm

Time-deflection curve Time-deflection rate (T=600OC F=550N)

0.01

0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12 14

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)

deflection (mm) deflection rate mm/h)

26

Sample: F92 CD-048 (600OC, 600N)

F92 CD-048 (600OC, 600N)

T=600OC

F=600N

CD-048

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

3.610h 0.129mm/h 1.789h 1.484mm


0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 0.5 1 1.5 2 2.5 3 3.5 4

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


27

Annex 2b. N/T-R samples

Sample: F92 CT-010 (650OC, 300N)

F92 CT-010 (650OC, 300N)

T=650OC

F=300N

CT-010

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

147.14h 0.0024mm/h 59.99h 1.351mm


0.001

0.01

0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 20 40 60 80 100 120 140 160

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


28

Sample: F92 CT-006 (650OC, 350N)

F92 CT-006 (650OC, 350N)

T=650OC

F=350N

CT-006

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

56.11h 0.006mm/h 29.34h 1.487mm


0.001

0.01

0.1

1

10

100

1000

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50 60

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


29

Sample: F92 CT-009 (600OC, 500N)

F92 CT-009 (600OC, 500N)

T=600OC

F=500N

CT-009

RUPTURE TIME

MIN DEFLECTION RATE


RATE

DEFLECTION AT MIN

DEFLECTION RATE

38.27h 0.0104mm/h 16.59h 1.489mm


0.01

0.1

1

10

100

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50

de

fle

ctio

n r

ate

(m

m/h

)

de

fle

ctio

n (

mm

)

time (h)


30

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31

KJ-N

A-2

9360-E

N-N

doi:10.2760/12580

ISBN 978-92-79-93959-4

Documents

Small Punch Creep Tests for Grade 92 Forgings · 2018. 10. 6. · Seven specimens Rwere extracted in the L and directions for the N/T F92 steel. These were compared to seven Q/T specimens