© 2016 NICHe, Tohoku University, All rights reserved …...and alloys were developed world-wide. Recently, in the field of Ni-based high-Cr alloys such as Alloy 52 or 152, susceptibility

© 2016 NICHe, Tohoku University, All rights reserved EPRI Conference, 2016

1st -4th, Aug., Chicago, Ill.

T. Yonezawa1), Y.Miyahara2), M.J.Peltonen3),

T.Sarikka3), A.Brederholm4), H.Hanninen3)

1) Tohoku University, 2) CRIEPI,

3) Aalto University, 4) Fennovoima Oy

Hot Cracking Susceptibility Evaluation of Alloy 52/152 Weld Metals

and Their Improvement


International Light Water Reactor Materials Reliability Conference and Exhibition 2016



1. Background

2. Objectives

3. Longi-Varestraint test

4. On-heating On-cooling hot ductility test

5. Five passes four layered beads build-up test

6. Mechanism on DDC & thermal cycling test

7. Discussion

8. Summary ２

Contents



1. Background

2. Objectives





7. Discussion

8. Summary 3

Contents



Many test techniques for hot cracking of austenitic steels

and alloys were developed world-wide.

Recently, in the field of Ni-based high-Cr alloys such as

Alloy 52 or 152, susceptibility to hot cracking (especially,

DDC (ductility dip cracking)) is shown to be different based

on the individual test technique.

On the other hand, more resistant filler metals to hot

cracking (especially DDC) than Alloys 52 and 152 are

desired.

1. Background

4



1. Background

2. Objectives





7. Discussion

8. Summary 5

Contents



To clarify the effect of chemical composition on hot cracking

susceptibility (especially DDC) of Ni based high Cr alloy.

To compare the hot cracking susceptibility based on various

conventional hot cracking tests.

To develop the new DDC susceptibility test which simulates

better the actual welding conditions and is more quantitative.

To develop more resistant filler metals to hot cracking

(especially DDC) than Alloys 52 and 152.

2. Objectives

6



1. Background

2. Objectives





7. Discussion

8. Summary 7

Contents



0 2 4 6 8 100

10

20

30

40

50

60

Argumented Strain / %

Tota

l C

rack L

ength

/ m

mNo.1 (Alloy 52, High Si, Mn)No.2 (Alloy 52, Low Si, Mn)No.3 (Alloy 52)No.4 (High Ni, Low Fe, T=35)No.5 (High Ni, Low Fe, T=33) No.10 (Alloy 132, Low C)

No.9 (Low C, Mn, Si)No.8 (High Ni, Low Fe, T=26)No.7 (High Ni, Low Fe, T=27)No.6 (High Ni, Low Fe, T=30)

Si, Al, Nb, Ti)

Chemical compositions and Longi-Varestraint test results for button melt heats

No. 9 was selected from the Longi-Varestraint

test results for 10 button melt heats

10 heats were melt by 1 kg button melt in vacuum.


8

C Si Mn P S Ni Cr Fe Al Nb Ti

1 0.019 0.72 2.18 0.005 0.0008 56.30 29.96 9.04 0.82 0.08 0.81

2 0.028 0.10 0.10 0.005 0.0017 58.94 30.04 9.04 0.82 0.09 0.80

3 0.024 0.35 0.99 0.005 0.0010 57.88 29.94 9.02 0.82 0.08 0.80

4 0.023 0.36 2.17 0.005 0.0010 58.50 30.10 7.06 0.79 0.08 0.80

5 0.022 0.37 2.18 0.005 0.0010 60.72 29.90 5.02 0.79 0.08 0.81

6 0.023 0.35 2.18 0.005 0.0009 62.53 30.08 3.04 0.79 0.08 0.80

7 0.023 0.36 2.19 0.005 0.0008 63.99 30.09 1.56 0.79 0.08 0.80

8 0.022 0.37 2.17 0.004 0.0009 65.70 29.96 0.43 0.80 0.08 0.80

9 0.006 0.10 0.99 0.005 0.0005 65.80 29.94 3.05 ˂0.002 ˂0.002 0.002

10 0.007 0.22 2.80 0.005 0.0008 70.50 14.98 9.48 ˂0.003 1.81 ˂0.002

52 Spec. ≦0.04 0.50 ≦1.00 ≦0.02 ≦0.015 Bal.28.0-

31.5

7.0-

11.0≦1.10 ≦0.10 ≦1.0

152 Spec. ≦0.05 ≦0.75 ≦5.00 ≦0.03 ≦0.015 Bal.28.0-

31.5

7.0-

12.0≦0.50 1.0-2.5 ≦0.50

No.Chemical Composition (%)



FCC, Ti(C,N) & M23C6 crystallization from

liquid of Ni-30Cr-9Fe-0.3Ti-0.03C-0.01N(wt.%)

: Eutectic M23C6 crystallizes in the final stage of solidification of Alloy 690.

L+fcc

L+fcc+Ti(C,N)

L+fcc+Ti(C,N)+M23C6

Te

mp

era

ture

(℃

)

Mole Fraction of Solid

Mole fraction of constituents of Ti (C,N)

49.7 49.2

① at 1390℃

75 25Liquidfcc Ti(C,N)

0.04

CTi0.4 0.7Cr N

49.9CTi

48.1 1.7Cr N

② at 1380℃

93 7Liquidfcc

0.06

0.3

Ti(C,N)

③ at 1295 to 1290℃

Eutectic M23C6 crystallizes

: For Ti(C,N) crystallization, TiN dominantly

crystallizes. TiC hardly crystallizes.

T.Yonezawa et al. (2011)

9Solidification simulation by Scheil’s model



y = 1717.8x - 51.675R² = 0.8129

0

10

20

30

40

50

60

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

Tota

l C

rack

Le

ngt

h (m

m)

Atomic Percentages of Crystarized (NbC + TiN + M23C6 +

MnS) Calculated from Chemical Composition (a/o)

Ni-30Cr alloy

Ni-15Cr alloy (132)

線形 (Ni-30Cr alloy)

The effect of atomic percentage of crystallized eutectic particles

(NbC+TiN+M23C6+MnS) on total crack length in Longi-Varestraint test

Linear approximation

(Ni-30Cr alloy)

Hot cracking susceptibility

based on the Longi-

Varestraint test increases

with increasing of eutectic

particles.

10




C Si Mn P S Ni Cr Mo Fe Al Nb Ti

Lab. Melt TD9 & 9R0.005 0.12 0.53 ≦0.002 0.0006 66.22 30.38 - 2..6 0.064 <0.002 0.003

Lab. Melt ZT0.003 0.10 0.50 0.004 0.0010 60.09 29.89 - 9.54 0.036 <0.002 <0.001

Lab. Melt WT or WB0.020 0.13 0.51 ≦0.001 0.0010 60.1 29.86 - 8.92 0.086 0.069 0.35

Lab. Melt VT or VB0.016 0.10 0.52 ≦0.001 0.0010 59.96 30.1 - 8.92 0.046 0.10 0.25

Lab. Melt XT or XB0.021 0.12 0.53 0.001 ≦0.001 60.47 28.02 - 8.10 <0.005 2.62 0.33

Lab. Melt B1 0.030 0.01 0.96 ≦0.001 0.001 55.85 30.19 ≦0.01 6.90 0.19 2.47 0.30

Lab. Melt B2 0.023 0.01 0.98 ≦0.001 ≦0.001 58.84 30.22 ≦0.01 8.07 0.19 1.97 0.30

Lab. Melt Simulate

52MSS0.020 0.01 0.97 ≦0.001 ≦0.001 58.71 30.15 4.02 3.00 0.19 2.47 0.30

Commercial

Alloy 52 0.027 0.16 0.24 0.002 <0.001 60.52 28.8 0.01 8.99 0.71 0.01 0.50

Chemical composition of 8 lab. heats and 1 heat of commercial Alloy 52

:Reduced element :Increased element 11




Longi-Varestraint test results for all lab. melt heats Hot cracking susceptibility based on the Longi-Varestraint test was improved by

decreasing of C, Si, Nb, Ti, Al contents.


0

10

20

30

40

50

60

0 2 4 6 8 10 12 14

Tota

l C

rack

Le

ngt

h（ｍｍ）

Augmented Strain（％）

No.1 Alloy52, High Si, Mn

No.2 Alloy52, Low Si, Mn

No.3 Alloy52

No.4 High Ni, Low Fe, T=35





No.9 Low C, Mn, Si

No.10 Alloy132, Low C

Lab. Melt 09R/TD9

Lab. Melt ZT

Lab. Melt ZT-2

Lab. Melt WT

Lab. Melt WT-2

Lab. Melt VT

Lab. Melt XT

Lab. Melt B1

Lab. Melt B2

Lab. Melt 52MSS

12



1. Background

2. Objectives





7. Discussion

8. Summary 13

Contents



Test specimen for On-heating、On-cooling hot ductility test

F.F.Noecker, J.N.Dupont：Weld. J. (2008)

On-heating, On-cooling hot ductility test conditions


14



On-heating, On-cooling hot ductility test

On-heating hot ductility test

•In vacuum or Ar gas

•Heating up to target temp. by 110 ℃/sec

•Hold temp. during 10 min

•Tensile test under 5 mm/sec

•Measure the rupture load & reduction

of area

On-cooling hot ductility test

•In vacuum or Ar gas

•Heating up to 1300 ℃ by 110 ℃/sec

•Hold temp. during 10 min

•Cooling to target temp. by 50 ℃/sec

•Hold temp. during 60 sec

•Tensile test under 5 mm/sec

•Measure the rupture load & reduction

of area


F.F.Noecker, J.N.Dupont：Weld. J. (2008)

15



On-heating and On-cooling hot-ductility test results

0

20

40

60

80

100

750 800 850 900 950 1000 1050 1100

69B基板材熱影響部

On－Heating

On-Cooling

試験温度(℃）Test Temperature (℃)

Red

uc

tio

n o

f A

rea

(%

)

On-heating

On-cooling test

The Longi-Varestraint and On-cooling hot ductility tests showed same tendency.

These tests are able to evaluate the solidification cracking and liquation cracking susceptibility.

But, are these tests able to evaluate the DDC susceptibility or not?


0

20

40

60

80

100

750 800 850 900 950 1000 1050 1100

On Cooling

9R 5209RHAZ69BHAZ

試験温度(℃）

Re

du

cti

on

of

Are

a (

%)

Test Temperature (℃)

On-cooling test 09R/TD9

16



1. Background

2. Objectives





7. Discussion

8. Summary 17

Contents



FPFLB test by 09R/TD9 wire

FPFLB test by Alloy 52 wire

Microscopy of the cross-sections for five passes four layered beads build-up & wash bead

(FPFLB) test specimens using commercial Alloy 52 and lab. melt 09R/TD9 wires.

Alloy 52 wire

Not Cracked

Alloy 52: 0.027C-29Cr - 9Fe -0.7Al - 0.01Nb - 0.5Ti

09R/TD9: 0.005C-30Cr-2.6Fe-0.06Al-0.002Nb-0.003Ti

Five Passes Bead

Wash Pass BeadWash pass bead

5 passes bead

4 layered beads build-up

1 wash pass layer

Strain Ratchet ？

MP

200oC

Welding cond.： Current：100 A、Voltage：10.5 V、Speed：12 cm/min、Wire：28 cm/min

Nov. 2011（Current：150 A、Voltage：10.5 V、Speed：12 cm/min、Wire：70 cm/min） C.D.Lundin, C.P.D.Chou:WRC Bulletin 289,24

Similar to Fissure Bend Test Specimen from

18

09R/TD9 wire

Cracked



①

100μ

m

③

100μ

m

52-D

1.6

-2

②

100μ

m

① ③②

FPFLB test by Alloy 52 wire

WT

-D1.2

-2

① ④② ③

FPFLB test by WB wire100μ

m

100μ

m100μ

m100μ

m

① ④② ③

Alloy 52: 0.027C-29Cr-90.7Al-0.01Nb-0.5Ti

WB: 0.02C-30Cr-9Fe-0.09Al-0.07Nb-0.35Ti

19



200μm 200μm200μm

Ⅰ Ⅱ Ⅲ

Ⅰ：Voids (connected)

Ⅱ：Shallow crack

Ⅲ：Open crack

Definitions of cracks observed on the cross-section

for FPFLB test


20



Alloy Ⅰ Ⅱ Ⅲ Σ Alloy Ⅰ Ⅱ Ⅲ Σ Alloy Ⅰ Ⅱ Ⅲ Σ

52

3 0 0 0

VB

>50 27 21 48Sim.

52

MSS

0 0 0 0

1 0 0 0 >50 10 11 21 0 0 0 0

0 0 1 1 >50 24 25 49 0 0 0 0

12 0 1 1 >50 30 18 48 0 0 0 0

WB

21 4 25 21

09R

/TD9

>50 1 0 1

18 3 21 18 >50 3 0 3

25 3 28 25 >50 12 0 12

28 10 38 28 >50 1 0 1

B1

0 0 0 0

B2

0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0

Σ = Ⅱ＋ Ⅲ

The FPFLB test should be simulate

better actual welding condition,

but, inferior to quantitative and

convenient evaluation on hot

cracking susceptibility.

21

Summary of FPFLB test Alloy 52 : 0.027C-29Cr- 9Fe- 0.7 Al- 0.01Nb- 0.5TiVB : 0.016C-30Cr- 9Fe- 0.05Al- 0.1Nb- 0.25TiWB : 0.02C - 30Cr- 9Fe- 0.09Al- 0.07Nb- 0.35Ti09R/TD9 : 0.005C-30Cr-2.6Fe- 0.06Al- 0.002Nb- 0.003TiB1 : 0.03C - 30Cr-6.9Fe- 0.19Al- 2.47Nb- 0.30TiB2 : 0.023C-30Cr-8.0Fe- 0.19Al- 1.97Nb- 0.30TiSim.52MSS: 0.020C-30Cr-3.0Fe-4.0Mo-0.19Al- 2.47Nb- 0.30Ti



1. Background

2. Objectives





7. Discussion

8. Summary 22

Contents



M.G.Collins & J.C.Lippold :Welding J. (2003), 288-s

DTR:Ductility-dip Temperature Range

BTR:Brittleness Temperature Range

23

“DTR” has been explained as the temperature range of 800 to 1,000oC, similar temperature range of “Red-hot

brittleness” due to FeS.

0

20

40

60

80

100

120

140

160

180

200

220

240

8009001000110012001300T

en

sile

Str

es

s (

MP

a),

E

lon

ga

tio

n,R

ed

uc

tio

n o

f A

rea

(%)

Test Temperature (oC)

Alloy 52Tensile Stress

Alloy 52Elongation

Alloy 52Reduction of Area

High temperature tensile test results for all

deposited material of commercial Alloy 52

C Si Mn P S Ni Cr Fe Al Nb Ti

0.027 0.16 0.24 0.002 <0.001 60.52 28.8 8.9 0.71 0.01 0.50Com. Alloy 52

But, S content of Alloy 52 is very low. DTR is not detected in Alloy 52.

6. Mechanism on DDC



24

Strain ratchet will be occurred with the high

primary stress and cyclic plastic deformation

due to thermal stress.

In case of multi-pass welded metal, strain ratchet

may be occurred by the high residual stress as

primary stress and cyclic large thermal stress as

secondary stress.

6. Mechanism on DDC

R.L.Roche et al.(1982)

Secondary cyclic stress

under primary stress

Cyclic stress without primary stress or

not so big cyclic stress

Ratchet strain

10

48

10

M8ｘ

P1

.25

8φ

24

2φ

2

M8ｘ

P1

.25



Tem

per

ature

(oC

)Time (sec.)

Load

(N

)

破断

1,042℃

1,027℃

09R/TD9

Crack Initiation

Fracture

Thermal cycling test results for lab. melt 09R/TD9(Tensile pre-load: 46 MPa)

46MPa

(90%TS at 1200oC)

Specimen fractured at the time of 11 thermal cycles.

25

Thermal

Cycling Test

200oC⇆1200oC

200oC⇆1100oC

200oC⇆1000oC

200oC⇆ 900oC

200oC⇆ 800oC

200oC⇆ 700oC

200oC⇆ 800oC

200oC⇆ 900oC

200oC⇆1000oC

200oC⇆1100oC

200oC⇆1200oC

200oC⇆1100oC

6. Thermal cycling test



Thermal cycling test results for commercial Alloy 52(Tensile pre-load: 46 MPa)

破断部近傍拡大

1,031℃

1,074℃

Crack Initiation

Fracture

Tem

per

ature

(oC

)

Time (sec.)

Lo

ad (

N)

52-1


26




Thermal cycling test results for lab. melt simulate 52MSS(Tensile pre-load: 46 MPa)

Tem

per

ature

Time (sec.)

Load

(N

)

Sim. 52MSS


Crack Initiation

Fracture

1012oC

998oC


27




Thermal cycling test results for lab. melt B1(Tensile pre-load: 46 MPa)



1,042℃

1,056℃

Crack Initiation

Fracture

Tem

per

ature

(oC

)

Time (sec.)

Load

(N

)

B1


28



1. Background

2. Objectives





7. Discussion

8. Summary 29

Contents



Comparison between various test results ◎>◎>○>△>×

Alloy Chemical CompositionHot Cracking Test

Longi-

Varestraint

On-cooling

Hot DuctilityFPFLB

Thermal

Cycling

Alloy52 0.027C-29Cr-9Fe-0.7Al-0.01Nb-0.5Ti × × ○ ○

09R/TD9 0.005C-30Cr-2.6Fe-0.06Al-0.002Nb-0.003Ti ◎ ◎ △ ×or△

ZT 0.003C-30Cr-9.5Fe-0.036Al-0.002Nb-0.001Ti ○ - - -

WT/WB 0.020C-30Cr-8.9Fe-0.086Al-0.069Nb-0.35Ti ◎ - × -

VT / VB 0.016C-30Cr-8.9Fe-0.046Al-0.10Nb-0.25Ti ○ - × -

XT / XB 0.021C-28Cr-8.1Fe-0.005Al-2.6Nb-0.33Ti △ - - -

B2 0.023C-30Cr-8.1Fe-0.19Al-1.97Nb-0.30Ti ○ - ◎ -

Sim.52MSS

0.020C-30Cr-3.0Fe-4.0Mo-0.19Al-2.47Nb-0.30Ti △ - ◎ ◎

B1 0.030C-30Cr-6.9Fe-0.19Al-2.47Nb-0.30Ti △ - ◎ ◎

7. Discussion

30



1. Background

2. Objectives





7. Discussion

8. Summary 31

Contents



The effect of chemical composition on hot cracking susceptibility of 30% Cr-Ni based alloys was studied on 18 laboratory melted heats and a commercial Alloy 52 by Longi-Varestraint test, On-cooling hot ductility test, 5 passes 4 layered beads build-up (FPFLB) test and thermal cycling test.

Hot cracking susceptibility based on the Longi-Varestraint and On-cooling hot ductility tests was improved by decreasing of C, Si, Nb, Ti, Al contents.

The hot cracking susceptibility based on the FPFLB test was not improved by decreasing of C, Si, Nb, Ti, Al contents, but improved by the addition of C and Nb content.

From these studies, it is concluded that the Longi-Varestraint and On-cooling hot ductility tests are able to evaluate the solidification cracking and liquation cracking, but they are not proper tests to evaluate the DDC susceptibility.

The FPFLB test should be simulate better actual welding condition, but, inferior to

quantitative and convenient evaluation on hot cracking susceptibility.

The DDC may be occurred by the strain ratcheting mechanism. Based on the test results a novel Gleeble test (thermal cycling test) is recommended to evaluate the DDC susceptibility, and a new 30% Cr-Ni based alloy for improving the hot cracking resistance is proposed.

8. Summary

32



Acknowledgements

This study was performed as a part of the collaboration research program between Aalto University, and Tohoku University.

The studies of Tohoku University and Aalto University have been financially supported by Mitsubishi Heavy Industries, Ltd. and Structural Integrity of Ni-base Alloy Welds-project of Tekes, Finland.

Authors would like to acknowledge their support. 33



Thank you for your kind attention !

34

Documents

© 2016 NICHe, Tohoku University, All rights reserved …...and alloys were developed world-wide. Recently, in the field of Ni-based high-Cr alloys such as Alloy 52 or 152, susceptibility