Dr. Peter L. Andresen - GE Global Research Center (retired) Al Ahluwalia … · 2016-07-29 · SCC...

SCC of Alloy 690, Alloy 152/52/52i Weld Metals and Dilution ZonesDr. Peter L. Andresen - GE Global Research Center (retired)

Al Ahluwalia – EPRI Project Manager

International Light Water Reactor Materials Reliability ConferenceChicago - August 2016

2

Context / Perspective ASME codes rely on the concept of SCC immunity, which is not helpful. Despite widespread opinion a decade ago, Alloy 690 is susceptible to SCC initiation and growth, and CGRs can be high. Lore (opinion without data) has been repeatedly found inaccurate: 690 homogeneity, 1D rolling as unique, CRDM as immune, GB carbides as beneficial, no ‘intentional’ cold work in plant components… To date, only low CGRs of 690 observed at < ~10% cold work, but several materials that exhibit the highest CGRs have not been evaluated. Almost all CGRs are low in 152/52/5i weld metals, even with DDC or weld repairs or with high IG morphology.

Exceptions occur primarily at one laboratory, where load fluctuations during testing may explain the difference. Excellent plant experience with 690 and 152/52 weld metals.

3

Context / Perspective High CGRs observed in some cases at ~ 12% cold work. High CGRs in best materials (CRDM) at 20% cold work. Despite “< 5% intentional cold work” policy, it is hard to ensure all components have <15 – 20% strain from incomplete annealing, fabrication / straightening and weld residual strain. Should employ “90th percentile” or similar. CGR evolution vs. time indicates susceptible paths exist; thus, some longer term testing is needed for evaluation. Temperature and H2 dependencies vanish in high CGR materials, so very high CGRs can persist down to < 290C. Comparisons of 600 vs. 690 at ~15% strain are limited but suggest an average of >100X difference in CGR and perhaps initiation. Expert Panel is creating an “scored database” that will be used to create CGR disposition curves for 690 & 152/52.

Must pay attention to problem data

4

Testing Approach 690 cold worked by forging or 1-D rolling or weld HAZ aligned:

• used dcpd resistivity correction • used ‘anticipatory’ dcpd correction for better K control

weld metal and HAZ-aligned and interface specimens evaluated 0.5T CT specimens in 360 ºC (290–360ºC) PWR primary water testing at 25 – 40+ ksiin, constant-K and “Varying-K”most H2 levels are near Ni/NiO at the test temperature good water chemistry: ~2 volume exchanges per hourmeasured potentials of 690 & Pt vs. Cu/Cu2O/ZrO2

Tests: 70 Alloy 690 base metal CTs 620,000+ hours26 Alloy 152/52 weld metal CTs 203,000+ hours

13 Alloy 690 “HAZ” CTs 108,000+ hours Totals: 109 CT Specimens 931,000+ hours

5

Summary of GE Data on 690, HAZ & Welds

GE CGRs for Alloy 690/152/52 can span a ~20,000X range to values as high as ~2 x 10–6 mm/s in PWR primary water.

6

20X Evolution in CGR Over ~1500 Hours

Very high growth rates, very stable SCC response.Note continuing evolution of CGR vs. time.

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.5

12.5

13.5

14.5

15.5

16.5

17.5

18.5

19.5

500 1000 1500 2000 2500 3000 3500 4000

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#2 - c521 - 690, ANL NX3297HK12, As-Rec'd, 31% Forge, S-L

Outlet conductivity x 0.01

CT potentialPt potential

c521 - 0.5TCT of 690 AR, 31% Forge, S-L30 ksiin, 360C, 600B/1Li, 26 cc/kg H2

To

Con

stan

t K

@ 1

268h

At 325C, pH = 7.74. At 300C, pH = 7.40

3.3 x 10-7

mm/s

To 9

000s

hol

d @

549

h

1.4 x 10-6

mm/s

6 x 10-8 mm/s

1.4 x 10–6

mm/s

7

31% 1D-CR 690 CRDM, RE243 – S-L

Moderately high growth rates, very stable SCC response,“normal” (but somewhat low) temperature dependency.

Very good agreement with PNNL data.

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

12.26

12.28

12.3

12.32

12.34

12.36

12.38

12.4

2000 2200 2400 2600 2800 3000 3200

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#5 - c471 - 690, RE243 As-Rec'd, 31% 1D Cold Rolled, S-L



c471 - 0.5TCT of 690 AR, 31% 1D CR, S-L25 ksiin, 360C 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

To C

onst

ant

K @

200

4h

1.3 x 10-8 mm/s

4.7 x 10-8

mm/s

To 3

25C

& 1

0.5

cc/k

g H

2@

231

1h

To 3

60C

& 2

6 cc

/kg

H2

@ 2

623h

5.0 x 10-8

mm/s

All materials/microstructures

5.0 x 10–8

mm/s

8

30% 2D-Deform (Forged) 690 CRDM, S670743– S-L

Very high growth rates, very stable SCC response.

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

19

19.2

19.4

19.6

19.8

20

1300 1350 1400 1450 1500 1550 1600 1650 1700

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#5a - c575 - 690, MHI CRDM, S670743, 30.3% Forge, S-L



c575 - 0.5TCT of 690 AR, 30% Forge, S-L44 MPam, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

7.6 x 10-7

mm/sK

~44

MPa

m @

131

0h

Test

End

@ 1

684h

Corrected Data

All materials/microstructures

7.6 x 10–7

mm/s

9

CGR Response at Lower CW

Astonishingly high CGR recently reported by Morton

on 20% CW 690.

Again demonstrating that we need to examine a diversity of

materials and conditions –as well as replicate specimens.

10

Very high growth rates in the S-L orientation vs. µS & CW Crack plane = Forging plane

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

12

13

14

15

16

17

18

19

20

21

500 1000 1500 2000 2500 3000 3500 4000

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Cra

ck le

ngth

, mm

Test Time, hours

SCC#2a - c521 - 690, ANL NX3297HK12, As-Rec'd, 31% Forge, S-L




To C

onst

ant

K @

126

8h

At 325C, pH = 7.74. At 300C, pH = 7.40

4.3 x 10-7

mm/s

To 9

000s

hol

d @

549

h

1.1 x 10-6

mm/s

9 x 10-8 mm/s

Test

End

@ 4

294h

40 M

Pam

@ 3

000h

53 M

Pam

@ 4

000h

Corrected Data

1.6 x 10-6

mm/s

31% Forged NX3297HK12 – S-L vs. µS

S-L vs. CW

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.31

11.32

11.33

11.34

11.35

11.36

11.37

11.38

11.39

11.4

500 700 900 1100 1300 1500 1700 1900 2100 2300

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Cra

ck le

ngth

, mm

Test Time, hours

SCC#2 - c522 - 690, ANL NX3297HK12, As-Rec'd, 31% Forge in Width, S-L



c522 - 0.5TCT of 690 AR, 31% Forge-W, S-L33 MPam, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

3.1 x 10-8

mm/s

~1 x 10-10 mm/s

To 9

000s

hol

d @

549

h

Corrected Data

K dropping due to crackadvance in other CT specimen

To C

onst

ant

K29

MPa

m @

126

8h

To C

onst

ant

K26

MPa

m @

126

8h

– S-L vs. µST-L vs. CW

Very low growth rates whenCrack plane Forging plane

1.1 x 10–6

mm/s

~1 x 10–10 mm/s

Orientation vs. Deformation

4.3 x 10–7

mm/s

3.1 x 10–8

mm/s

11

31% Forged (Longitudinal) CRDM WQ199 – S-L

Very similar growth rates in all µS orientations when the Crack plane = Forging plane

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

15.85

15.9

15.95

16

16.05

16.1

16.15

16.2

16.25

4200 4400 4600 4800 5000 5200

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Crac

k le

ngth

, mm

Test Time, hours




At 325C, pH = 7.74. At 300C, pH = 7.40

5.7 x 10-8

mm/s

To 9

000s

hol

d @

364

3h

To C

onst

ant

K @

438

7h2.8 x 10-7

mm/s

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.8

11.9

12

12.1

12.2

12.3

12.4

1500 2000 2500 3000 3500 4000

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

, , g ,



c619 - 0.5TCT of 690 AR, 31% Forge in C, S-L33 MPam, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

* 5% fall, 95% rise (~500s)

7.8 x 10-8

mm/s

To

Con

stan

t K

@ 1

503h

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

12.1

12.15

12.2

12.25

12.3

12.35

12.4

12.45

12.5

12.55

12.6

1500 2000 2500 3000 3500 4000

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Crac

k le

ngth

, mm

Test Time, hours



c620 - 0.5TCT of 690 AR, 31% Forge in R, S-L33 MPam, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

* 5% fall, 95% rise (~500s

5.2 x 10-8

mm/s

To C

onst

ant

K @

150

3h

5.7 x 10–8

mm/s7.8 x 10–8

mm/s

5.2 x 10–8

mm/s

Orientation vs. Deformation

SCC susceptibility followsplane of cold work

12

Must Be Clear on Orientation

The intent of the ASTM orientation designations is to define the crack plane in relation to important processing conditions. This is true whether we’re referring to the original ‘mill’ processing or subsequent processing or welding.

There is agreement on designating weld orientations as T-S completely independent of the product orientation, and the same approach should be taken with added forging or rolling or welding.

690 Database distinguishes orientation vs. ‘product form’ and orientation vs. ‘cold work’ or welding.

13

31% 1D-CR 690 CRDM, RE243 – S-L

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

12.26

12.28

12.3

12.32

12.34

12.36

12.38

12.4

2000 2200 2400 2600 2800 3000 3200

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#5 - c471 - 690, RE243 As-Rec'd, 31% 1D Cold Rolled, S-L



c471 - 0.5TCT of 690 AR, 31% 1D CR, S-L25 ksiin, 360C 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

To C

onst

ant

K @

200

4h

1.3 x 10-8 mm/s

4.7 x 10-8

mm/s

To 3

25C

& 1

0.5

cc/k

g H

2@

231

1h

To 3

60C

& 2

6 cc

/kg

H2

@ 2

623h

5.0 x 10-8

mm/s

GB carbides not beneficial

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.12

11.125

11.13

11.135

11.14

850 950 1050 1150 1250 1350

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Crac

k le

ngth

, mm

Test Time, hours

SCC#2a - c472 - 690, RE243 C Modified, 31% 1D Cold Rolled, S-L



c472 - 0.5TCT of 690 CM, 31% 1D CR, S-L25 ksiin, 360C 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

To 9

000s

hol

d @

847

h

3 x 10-9 mm/s

To C

onst

ant

K @

106

3h

1.8 x 10-8

mm/s

GB Carbides Removed

3 x 10–9

mm/s

5.0 x 10–8

mm/s

GB carbides are beneficial in susceptible materials like Alloy 600, but should perhaps be eliminated from Alloy 690

14

31% 2D-Deform (Forged) 690 Plate, NX3279HK– S-L

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.5

12.5

13.5

14.5

15.5

16.5

17.5

18.5

19.5

500 1000 1500 2000 2500 3000 3500 4000

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#2 - c521 - 690, ANL NX3297HK12, As-Rec'd, 31% Forge, S-L



c521 - 0.5TCT of 690 AR, 31% Forge, S-L30 ksiin, 360C, 600B/1Li, 26 cc/kg H2

To C

onst

ant

K @

126

8h

At 325C, pH = 7.74. At 300C, pH = 7.40

3.3 x 10-7

mm/s

To 9

000s

hol

d @

549

h

1.4 x 10-6

mm/s

6 x 10-8 mm/s

GB carbides not beneficial

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.24

11.26

11.28

11.3

11.32

11.34

11.36

1500 1700 1900 2100 2300 2500 2700 2900 3100 3300

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Crac

k le

ngth

, mm

Test Time, hours

SCC#3 - c621 - 690, ANL NX3297HK12, Soln Ann, 30% Forge, S-L



c621 - 0.5TCT of 690 SA, 30% Forge, S-L33 MPam, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

1.9 x 10-8

mm/s

* 5% fall, 95% (~500s) rise, ~500s hold

To C

onst

ant

K @

274

7h

8.0 x 10-9

mm/s

To 8

5,90

0s h

old*

@ 1

529h

GB Carbides Removed

8 x 10–9

mm/s

1.4 x 10–6

mm/s

GB carbides are beneficial in susceptible materials like Alloy 600, but should perhaps be eliminated from Alloy 690

15

33% Cold Forged T-K 114092 – S-L

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

13

13.5

14

14.5

15

15.5

16

1400 1900 2400 2900 3400 3900 4400

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Crac

k le

ngth

, mm

Test Time, hours

SCC#4 - c546 - 690, T-K 114092, As-Rec'd, 33% Forge, S-L




At 325C, pH = 7.74. At 300C, pH = 7.40

8 x 10-8 mm/s

9 x 10-7

mm/s

To C

onst

nat

K @

141

6h

47 M

Pam

@ 4

000h

41 M

Pam

@ 3

000h

Test

End

@ 4

372h

Corrected Data

4 x 10-7

mm/s

Hot deformation

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.09

11.1

11.11

11.12

11.13

11.14

11.15

11.16

11.17

600 1100 1600 2100 2600 3100

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Cra

ck le

ngth

, mm

Test Time, hours

SCC#2 - c617 - 690, 116092, 30% HForge @1300F in Th, S-L



c617 - 0.5TCT of 690 AR, 30% Hot Forge, S-L33 MPam, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

5.1 x 10-9

mm/s

* 5% fall, 95% rise (~500s)

To 2

8,30

0s h

old*

@ 1

371h

To 8

5,90

0s h

old*

@ 2

590h

2.6 x 10-9

mm/s

To 9

000s

hol

d* @

601

h

1.5 x 10-8

mm/s

Cold forged vs.

Hot forged

9 x 10–7

mm/s

2.6 x 10–9

mm/s

Low growth rates when hot forged, but residual strain is somewhat lower

16

Hot Forging vs. Cold Forging

Low growth rates when hot forged, but residual strain is somewhat lower

Hot deformation

17

13% Forged CRDM WQ199 – S-L

Low growth rates at 13% cold forge

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.02

11.025

11.03

11.035

11.04

11.045

800 1000 1200 1400 1600 1800 2000

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Cra

ck le

ngth

, mm

Test Time, hours

SCC#2a - c585 - 690, CRDM WQ199, As-Rec'd, 15% Forge, S-L




At 325C, pH = 7.74. At 300C, pH = 7.40

1.4 x 10-8

mm/s

To

9000

s ho

ld*

@ 2

50h

1 x 10-9 mm/s

* 5% fall, 95% (~500s) riseTo C

onst

ant

K @

126

9h

Lower deformation

1 x 10–9

mm/s

18

13% Forged Plate NX3297HK12 – S-L

Low growth rates at 13% cold forge.Other heats show medium & high growth rates at ~12% cold work.

19

16% Forged 133454 – S-L

Medium growth rates at 16% cold forge

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

13.85

13.9

13.95

14

14.05

14.1

14.15

14.2

14.25

14.3

5000 6000 7000 8000 9000 10000 11000

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#5 - c664 - 690, 133454, 16% Forge, S-L




At 325C, pH = 7.74. At 300C, pH = 7.40

* 5% fall, 95% rise (~500s)

2.3 x 10-8

mm/s

1.9 x 10-8

mm/s

To 2

7.3

ks h

old

@ 5

573h

To C

onst

ant

K

@ 8

641h

To 8

5.4

ks h

old

@ 6

786h

2.5 x 10-8

mm/s

1.9 x 10–8

mm/s

20

20% Forged NX3297HK12 – S-L


-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

14.38

14.43

14.48

14.53

14.58

8000 8500 9000 9500 10000 10500 11000

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#7 - c670 - 690, NX3297HK12, 20%CF, S-L




At 325C, pH = 7.74. At 300C, pH = 7.40

* 5% fall, 95% rise time

3.1 x 10-8

mm/s

Con

stan

t K

@ 9

661h

85,4

00s

hold

* @

797

5h

2.2 x 10-8

mm/s

To 4

4 M

Pam

, R=0

.6, 0

.001

Hz

@ 6

259h

2.2 x 10–8

mm/s

21

13% Forged NX3297HK12 – S-L


-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

14.87

14.88

14.89

14.9

14.91

14.92

14.93

14.94

8000 8500 9000 9500 10000 10500 11000

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Cra

ck le

ngth

, mm

Test Time, hours

SCC#7 - c671 - 690, NX3297HK12, 13%CF, S-L




At 325C, pH = 7.74. At 300C, pH = 7.40

* 5% fall, 95% rise time

4.6 x 10-9

mm/s

Con

stan

t K

@ 9

611h

85,4

00s

hold

* @

797

5h

To 4

4 M

Pam

, R=0

.6, 0

.001

Hz

@ 6

259h

8.2 x 10-9

mm/s

8.2 x 10–9

mm/s

22

3 x 10-7 mm/s

5 x 10-9 mm/s

5 x 10-8

Med

ium

, H

igh,

Ver

y H

igh

CGR Response at Lower CW

12% Bettis data below show medium, high & very high CGRs.

5 x 10-8 mm/s

GE GRC data show medium CGRs with 16% cold forged

23

HAZ of KAPL Narrow Gap Weld – S-L

Medium growth rates in HAZ –perhaps 10 – 20X faster than as-received Alloy 690

7 x 10–9

mm/s

24

Weld residual strain typically peaks at >20% equivalent room temperature strain

Weld Residual Strain Effects on SCC

11.2

11.3

11.4

11.5

11.6

11.7

11.8

11.9

0 100 200 300 400 500 600 700 800

Time, hours

Cra

ck L

engt

h, m

m

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Con

duct

ivity

, uS/

cm o

r Pot

entia

l, V s

he

288 C, 1500 psi2000 ppb O2, Pure Water

3.16 x 10-7 mm/s

Constant K = 27.5 MPa/m

SCC of c111 - 0.5T CT of HEW Nb-SS 1.4550S* FLW Pipe, HAZ Aligned

Corrosion Potential of CT

Outlet Conductivity

Corrosion Potential of Pt

2.18 x 10-7 mm/s

To 2

00 p

pb O

2 at

565

h

High growth rates if align crack along SS HAZ

25

Unsensitized Type 321 Stainless Steel

Weld residual strain typically peaks at >20% equivalent room temperature strain,

and SCC often follows these high-strain areas.

26

Residual strains reach 40 – 50% in isolated dendrites of the weld metal, 18 – 21% in unmixed & partially melted zone, and

~14% in HAZ. Plate has ~8 – 10% retained strain (away from weld).

Weld Residual Strain in 690 & Welds: Steam Generator Divider Plate Mockup

Weld metal 690 composition

27

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

11.3

11.35

11.4

11.45

11.5

11.55

11.6

11.65

11.7

22 27 32 37 42 47 52 57

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Cra

ck le

ngth

, mm

Test Time, hours

SCC#1 - c757 - Alloy 600, 93511, SA+15.8%CF, S-L

Outlet conductivity x0.01

CT potential Pt potential

c757 - 0.5TCT of A600, SA+15.8%CF, S-L27.5 MPam, 360C, 1500 ppm B, 2.5 ppm Li

2.7 x 10-6

mm/s

33 M

Pam

, R=0

.6, 0

.01

Hz

@ 2

2.1h

2.7 x 10-6

mm/s

At 325C, pH = 7.22. At 300C, pH = 6.86

To 9

500s

hol

d @

35h

To 8

5,90

0s h

old

@ 4

4h

0.00

1 H

z @

23.

7h 3.8 x 10-6

mm/s To C

onst

ant

K=

27.5

MPa

m @

53h

Alloy 600 + 15.8% Cold Forging

Consistent very high CGRs in 15.8% CW Alloy 600 (no GB carbides) perhaps 100X faster than most ~15% CW 690

2.7 x 10–6

mm/s

28

Must Compare 690 vs. 600

Astonishingly high CGR reported by Morton on

20% CW 690.

Reinforcing the need to examine a diversity of

materials and conditions.

Very high CGRs observed in 15.8% cold worked Alloy 600 without GB

carbides

29

Weld Metals Have Very Inhomogeneous Strain

Strain concentrates in isolated dendrites (red)

This was avoided in MPR-115 by requiring sufficient crack advance.

30

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

11.46

11.465

11.47

11.475

11.48

11.485

11.49

11.495

1500 2000 2500 3000 3500 4000

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Cra

ck le

ngth

, mm

Test Time, hours

SCC#2 - c541 - Alloy 152 Weld, ANL, WC04F6, As-Welded, T-S



c541 - 0.5TCT of 152 Weld, T-S30 ksiin, 360C, 600B/1Li, 26 cc/kg H2

To C

onst

ant

K @

188

2h

At 325C, pH = 7.74. At 300C, pH = 7.40

1.7 x 10-8

mm/s

To ~

1000

s ri

se t

ime,

90

00s

hold

@ 1

275h 8 x 10-10 mm/s

30

SCC of Alloy 152 Weld MetalC541, ANL, WC04F6

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

12.82

12.825

12.83

12.835

12.84

12.845

12.85

12.855

6400 6600 6800 7000 7200 7400 7600 7800

Cond

uctiv

ity,

S/cm

or P

oten

tial,

V she

Cra

ck le

ngth

, mm

Test Time, hours

SCC#5 - c541 - Alloy 152 Weld, ANL, WC04F6, As-Welded, T-S



c541 - 0.5TCT of 152 Weld, T-S30 ksiin, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

7 x 10-10 mm/s

2.4 x 10-8

mm/s

To 8

5,90

0s h

old

@ 6

528h

To 9

000s

hol

d @

500

2h

To C

onst

ant

K @

715

6h3 x 10-9 mm/s

Three SCC attempts covering 12,264 hours of

testing – low CGRs, moderate fraction IG

8 x 10–10 mm/s

7 x 10–10 mm/s

31

C541: ANL Alloy 152 Weld Metal

Three SCC attempts covering 12,264 hours of testing – low CGRs, moderate fraction IG

32

SCC of Alloy 152 Weld Metal

Transitioned for 0.50 mm at slow rise times.

Extensive IG morphology.

So far, one SCC attempt covering 7,499 hours of testing – low

CGRs

C555, MHI, 706447

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

12.895

12.9

12.905

12.91

12.915

12.92

12.925

12.93

12.935

5000 5500 6000 6500 7000 7500

Con

duct

ivity

, S/

cm o

r Pot

entia

l, V s

he

Crac

k le

ngth

, mm

Test Time, hours

SCC#5 - c555 - Alloy 152 Weld on Plate, MHI SMAW DM, 706447, As-Welded, T-S



c555 - 0.5TCT of 152 Weld, T-S33 MPam, 360C, 600B/1Li, 26 cc/kg H2

At 325C, pH = 7.74. At 300C, pH = 7.40

1.2 x 10-8

mm/s

To 2

7,00

0s h

old

@ 4

937h

4 x 10-10 mm/s

To C

onst

ant

K @

563

5h

* 5% fall, 95% rise (~500s)

Corrected Data

Test

End

@ 7

499h

4 x 10–10 mm/s

33

High Cr Welds in BWR Water

All 52i / 52 / 152 welds show low growth rates despite being tested at high K, in 2 ppm O2 and 30 – 50 ppb sulfate or chloride.

34

Key Findings Alloy 690 is susceptible to SCC initiation and growth.

The best Alloy 690 (e.g., CRDM) is very homogeneous; but can still exhibit very high CGRs if cold worked >20%.

1-D cold rolling and forging give similar CGRs.

GB carbides are not beneficial, at least when CW exists.

30% cold work is not very susceptible without GB carbides.

CGR evolution vs. time suggests more susceptible paths exist.

Temp & H2 dependencies vanish in high CGR materials.

When crack plane is not aligned with CW plane, much lower CGRs are observed even if aligned with microstructural banding.

We see medium CGRs at ~15% CW; others see higher CGRs.

35

Recommendations We should focus on identifying ‘vulnerabilities’ in alloys, then

work hard to avoid them.

The origin of very high CGRs in some heats of 690 need to be understood, and effects of 5 – 15% cold work evaluated.

Weld interfaces – esp. with SS and LAS – need to be understood and SCC CGRs quantified.

More characterization of weld residual strains, and composition & microstructures of weld interfaces is needed.

Evaluation of higher SCC susceptibility from elevated hardness / yield strength in PWHT (tempered) low alloy steel welds & temper bead welds is needed.

SCC in LAS is strongly accelerated at higher yield strength.

Dr. Peter L. Andresen - GE Global Research Center (retired) Al Ahluwalia … · 2016-07-29 · SCC...

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Transcript of Dr. Peter L. Andresen - GE Global Research Center (retired) Al Ahluwalia … · 2016-07-29 · SCC...