Serco, Ciemat, MHI

1

Overview of SCC Programs at SERCO, Ciemat and MHI

Peter AndresenGE Global Research Center

NRC-EPRI Meeting June 2011

Serco, Ciemat, MHI

Serco – Summary of Materials Tested• GE MATERIAL: S-L, 20%CW (2 PASSES), CGR 1.3-2.3X10-8 mm/s

– SUPPLIED IN CW FORM BY GE-GRC

• ANL MATERIAL: S-L, 26%CW (3 PASSES), CGR 1.9-4X10-7 mm/s

– SUPPLIED IN CW FORM BY GE-GRC

• ALLVAC BAR (// TO BANDING): S-L, 20%CW (10 PASS), 9.8X10-9 mm/s

– HEAVILY BANDED MATERIAL

• ALLVAC BAR (┴ TO BANDING): S-L, 20%CW (8 PASS), 4X10-9 mm/s

• VALINOX CRDM: S-L, 20%CW (4 PASS), CGR 1.4X10-8 mm/s

Not listed, but most of Serco’s 690 data is at 350C

Serco Research Summary

Serco, Ciemat, MHI

Comparative rates + classification

1.0E-13

1.0E-12

1.0E-11

1.0E-10

1.0E-09

1.0E-08

0 10 20 30 40 50

Stress intensity factor, K (MPam0.5)

crac

k gr

owth

rate

(m/s

)

Serco Valinox (CW20% S-L)Serco Heat 1 (CW20% S-L)Serco Heat 2 (CW26% S-L H2 Varied)Serco Allvac (CW20% with banding, S-L)Serco Allvac (CW 20% norm to banding, S-L)Bettis 338C (CW24% S-L)Bettis 360C (CW24% S-L)GE Heat 1 (CW20% S-LGE Heat 2 (CW26% S-L)GEG CRDM (CW20% T-L)PNNL Heat 1 (CW20% S-L)PNNL Heat 2 (CW26% S-L)PNNL Valinox (CW17% S-L)ANL Heat 2 (CW26% S-L)MRP55 A600 (325C)

V. Low

Low

Med

High

V. High

Serco, Ciemat, MHI

Effect of Hydrogen Content on Crack Growth Rate ANL heat NX3297HK12

Apparent reduction in crack growth rate at high dissolved H2 concentration

12

3

45

6

7

8

0

1E-10

2E-10

3E-10

4E-10

5E-10

6E-10

7E-10

8E-10

9E-10

0 5 10 15 20 25 30 35 40 45 50

H2 Content (cc/kg)

CG

R (m

/s)

Possibly invalid data

Serco, Ciemat, MHI

Most data bounded by non-CW Alloy 600 superposition model.26% CW ANL heat showed significantly higher rates.

1.E-14

1.E-13

1.E-12

1.E-11

1.E-10

1.E-09

1.E-08

1.E-07

1.E-14 1.E-13 1.E-12 1.E-11 1.E-10 1.E-09 1.E-08 1.E-07

A600 ASME air rate

CG

R E

nv

1HU (ANL 26%CW S-L)2HU (GE 20%CW S-L)3HU (Allvac //toB 20%CW S-L)8HU (Allvac n to B 20%CW S-L) 14HU (Valinox 20%CW S-L)ASME A600 Airx5A600 Env lineA600 SCC

Data Presentation on Corrosion Fatigue

Superposition Model

SCCCFairenv aaaa

Q = 80 KJ/molα = 1.5 x 10-13

Susceptible ANL Mtl

9000

s

1000

s

0.00

1Hz

0.01

Hz

0.05

Hz

Serco, Ciemat, MHI

Current test - ‘Aggressive’ rolling effects• Investigate variability in rolling method to achieve equivalent reduction in

thickness.– Usually dependent on machine limits.

• It has been suggested that the number of passes used when cold rolling may affect the susceptibility and CGR.

• Testing Allvac billet material (heavily banded).– Deliberate ploy to concentrate on one (Allvac) Material.

• 20%CW 1D rolled, with 4 or 10 passes (SL, banding along rolling direction)

• Also looking at CGR with respect to direction of rolling.• 3 specimen test

– 10 pass specimen as in previous test– two 4 pass specimens cut as shown

roll

Serco, Ciemat, MHI

In-test Data

Very similar rates for 4 and 10 passes.

Con

st. L

oad.

H2

19cc

/kg

Con

st L

oad.

H2

35cc

/kg

Con

st L

oad

H2

19cc

/kg

10.825

10.830

10.835

10.840

10.845

10.850

10.855

10.860

2100 2300 2500 2700 2900 3100 3300 3500 3700 3900Time (hrs)

a (m

m)

4HU

& 2

0HU

10.785

10.790

10.795

10.800

10.805

10.810

10.815

10.820

a (m

m)

23H

U

4HU 10 passes

20HU 4 passes

23HU 4 passes

IN-TEST UNCORRECTED DATA

4.66-6.75 x10-12 m/s(Low-Med)

3.20-4.96 x10-12 m/s(Low)

3.15-5.25 x10-12 m/s(Low)

4.33 x10-12 m/s(Low)

2.85 x10-12 m/s(Low)

2.17 x10-12 m/s(Low)

3.52 x10-12 m/s(Low)

2.23 x10-12 m/s(Low)

3.05 x10-12 m/s(Low)

Serco, Ciemat, MHI

Upcoming Test - Single Pull Allvac Material• Compare CGRs with those of previous tests

that performed CW by uni-directional cold rolling and forging.

• For direct relation to Cold Working by rolling, performed tensile tests on material CW by 0, 10 and 20% to measure the proof stress.

• Related proof stress to % thickness reduction to calculate true stress to be applied by single pull.

• SCC Tests in ‘Along’ (R-L) and ‘Across’ (L-R) orientations

• Compare hardness profiles and microstructures.

• More representative of weld shrinkage?

Across(L-R)

Along(R-L)

Serco, Ciemat, MHI

Tensile Data of CW Material

y = 20.283x + 296.61

0

100

200

300

400

500

600

700

800

0 5 10 15 20 25

% CW by Rolling

Yiel

d (0

.2%

) Str

ess

(MPa

)

0% CW by rolling20% CW by rolling10% CW by rollingAveragesLinear (Averages)

Serco, Ciemat, MHI

Single Pull Method

• Applied True Stress of 700MPa.• Limited material available, making 8mm CTs.

– Validity of specimens and available ligament compared with arguments in ASTM 647 and paper by P. Andresen at 11th Env Deg, K/size effects.

• Test alongside a CT from a 20% 1D cold rolled specimen (Allvac ┴ to banding) as control for size effects with an already tested material.

Serco, Ciemat, MHI

SERCO Summary• SCC testing of four materials

– GE Plate, ANL Plate, Allvac Bar and Valinox CRDM.– All Low-Med rates with exception of ANL heat (High).– Possible H2 effect measured on susceptible ANL heat.

• Ongoing comparison of data between laboratories• Concentrating on systematic evaluation of single

material - Allvac bar– Alignment to banding– Hydrogen effects– Number of passes used for Cold Rolling– Single Pull, comparing application of cold work.

1

MATERIALS DIVISION

Influence of rolling and tensile deformation on the Alloy 690 CGR UNESA-EPRI Project

D. Gómez-Briceño, J. Lapeña, M. S. García, L. Castro, F. Perosanz (CIEMAT)L. Francia (UNESA)

K. Ahluwalia - EPRI manager

Dresden, Germany. May 9, 2011

2

MATERIALS DIVISION

To compare the response of Alloy 690 TT deformed by rolling and tensile to SCC in primary water conditions.

Material have been deformed up to 20%

CGR tests have been performed in primary water conditions at 325ºC

CT specimens (12 mm thickness) with T-Lorientation

CRDM Alloy 690TT tubesupplied by Valinox (heat WP 787)

Objective and scope

3

MATERIALS DIVISION

CRDM Alloy 690TT tube supplied by Valinox(heat WP 787)Electric Arc Furnace + ESR (Electroslag Remelt)Thermal treatment : 1050ºC, 6 hours at 715ºC

Homogeneous microstructure, high grain boundary coverage with small carbides, no banding. Grain size ASTM No 3.5-4 (∼ 90 µm)

Material has been deformed up to 20% by rolling in three passes and by straining tensile

Average HardnessAs received: 165HV1Tensile deformed : 279HV1Rolling deformed : 298HV1

0 5 10 15 20 25 30 35 40 45 50 55 600

200

400

600

800

1000

As receivedCW by tensile

CW by rolling

CRDM, Alloy 69020% CW, orientation L325 ºC

Stre

ss (M

Pa)

Strain (%)

Materials

4

MATERIALS DIVISION

900 ppm B, 2.5 ppm Li,pH=7.2 at 310ºCH2 = 35 cc/Kg H2O at 325ºC ( )

280 300 320 340 360 3800

10

20

30

40

NiO Regime

[H2]

in N

i/NiO

trans

ition

line

(cc/

kg)

Temperature (°C)

Ni Regime

280 300 320 340 360 3800

10

20

30

40

280 300 320 340 360 3800

10

20

30

40

NiO Regime

[H2]

in N

i/NiO

trans

ition

line

(cc/

kg)

Temperature (°C)

Ni Regime

Four CT specimens in daisy chain. All of them instrumented by DCPDPre-cracking in air: R =0.3 to 0.7and 1-2 Hz Fatigue pre-cracking in high T water: R=0.7 and 0.05 -0,01-0,001HzConstant Load (CL) with gentle unloading: 0.001Hz + 9000 s and 24h hold time Pure constant load.

Experimental conditions

5

MATERIALS DIVISION

4000 6000 8000 100001.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

HT

24 h

HT

24 h

at 5

151

h

0.01

Hz

at 5

687

hH

T 24

h a

t 581

3 h

0.01

Hz

at 6

988

hH

T 9

ks a

t 718

1 h

HT

24 h

at 8

902

h

CL

at 9

213

h

∆a

(mm

)

Time (hours)

0.01

Hz

at 5

102

h

CRDM 690, 20% CW by rolling, specimen 9L1325 ºC, 35 MPa m1/2, 35 ccH2/kgH2O

1.6x10-8 mm/s

2x10-8 mm/s

2x10-8 mm/s1.6x10-8 mm/s

DCPD data during hold time and constant load periods (corrected by fractography)

Specimen 9L1. 20% CW by rolling. CRDM tube WP787325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

7

MATERIALS DIVISION

12 3

2

Intergranular areas at the crack tip

Specimen 9L1. 20% CW by rolling. CRDM tube WP787325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

10

MATERIALS DIVISION

4000 6000 8000 100001.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

HT

24 h

HT

24 h

at 5

151

h

0.01

Hz

at 5

687

hH

T 24

h a

t 581

3 h

0.01

Hz

at 6

988

hH

T 9

ks a

t 718

1 h

HT

24 h

at 8

902

h

CL

at 9

213

h

∆a (m

m)

Time (hours)

0.01

Hz

at 5

102

h

CRDM 690, 20% CW by rolling, specimen 9L2325 ºC, 35 MPa m1/2, 35 ccH2/kgH2O

9x10-9 mm/s7x10-9 mm/s

3.8x10-8 mm/s

1.7x10-8 mm/s

DCPD data during hold time and constant load periods (corrected by fractography)

Specimen 9L2. 20% CW by rolling. CRDM tube WP787325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

11

MATERIALS DIVISION

The fracture appearance is very similar to the specimen 9L1Estimated final KI = 36.8 MPa√m

Specimen 9L2. 20% CW by rolling. CRDM tube WP787325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

14

MATERIALS DIVISION

4000 6000 8000 100001.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

HT

24 h

HT

24 h

at 5

151

h

0.01

Hz

at 5

687

hH

T 24

h a

t 581

3 h

0.01

Hz

at 6

988

hH

T 9

ks a

t 718

1 h

HT

24 h

at 8

902

h

CL

at 9

213

h

∆a (m

m)

Time (hours)

0.01

Hz

at 5

102

h

CRDM 690, 20% CW by tensile, specimen 9T1325 ºC, 35 MPa m1/2, 35 ccH2/kgH2O

1.5x10-8 mm/s1.5x10-8 mm/s

8.2x10-9 mm/s

8.6x10-9 mm/s

DCPD data during hold time and constant load periods (corrected by fractography)

Specimen 9T1. 20% CW by tensile. CRDM tube WP787325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

19

MATERIALS DIVISION

4000 6000 8000 100001.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

HT

24 h H

T 24

h a

t 515

1 h

0.01

Hz

at 5

687

hH

T 24

h a

t 581

3 h

0.01

Hz

at 6

988

hH

T 9

ks a

t 718

1 h

HT

24 h

at 8

902

h

CL

at 9

213

h

∆a

(mm

)

Time (hours)

0.01

Hz

at 5

102

h

CRDM 690, 20% CW by tensile, specimen 9T2325 ºC, 35 MPa m1/2, 35 ccH2/kgH2O

1.8x10-8 mm/s

1.5x10-8 mm/s

1.6x10-8 mm/s

1.7x10-8 mm/s

DCPD data during hold time and constant load periods (corrected by fractography)

Specimen 9T2. 20% CW by tensile. CRDM tube WP787325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

20

MATERIALS DIVISION

Fracture surface is mainly TG. Only minor IG isolated areas have been found at the crack tip, but more than in the specimen 9T1

Isolated grains are found in the commencement of Hold Time periods.Estimated final KI = 37.7 MPa√m

Specimen 9T2. 20% CW by tensile. CRDM tube WP787325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

23

MATERIALS DIVISION

CGR by DCPD signal, corrected by fractography

CGR is higher in the CRDM Alloy 690TT cold worked by rolling than by tensile straining

0.01E-9

1E-8

1E-7

1E-6C

GR

(mm

/s)

CRDM tube WP787, 20% CW, 325ºC35ccH2/kgH2O, KI= 37MPam1/2

CW by rollingCW by tensile

Hold Time9000 s

Maximum IG CGRat Constant Load

Hold Time24 hours

Constant Load

MRP-55 (KI = 37 MPa √m)

By fractography

Summary of results. CRDM tube WP787. 20% CW325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

24

MATERIALS DIVISION

10 15 20 25 30 35 40 45 501E-10

1E-9

1E-8

1E-7

1E-6

CRDM Cold WorkedT-L specimens

MRP CIEMAT 20% CR 325ºC, 35 ccH2/kgH2O CIEMAT 20% Tensile 325ºC, 35 ccH2/kgH2O GE 20% CF 360ºC 18 ccH2/kgH2O GE 41% CF 340ºC 18 ccH2/kgH2O PNNL 30% CR 350ºC, 29 ccH2/kgH2O SERCO 20% CR 350ºC, 19 ccH2/kgH2O

Cra

ck G

row

th R

ate,

da/

dt (m

m/s

)

Stress Intensity Factor, K (MPa√m)

Alloy 600 MRP-55 Curve

CRDM 20-41 % Cold WorkedT-L orientation, Temp. 325-360ºCH2: 18-35 ccH2/kgH2O

Summary of results. CRDM tube WP787. 20% CWComparison with other laboratories

25

MATERIALS DIVISION

Under Constant Load, CGRs for rolling material is higher than CGRs for tensile strained material

The specimens CW by rolling show larger IG areas than the ones CW by tensile straining

Small secondary cracks have been only observed in the specimens CW by rolling

Mainly Transgranular morphology has been associated to the Hold Time periods.

Summary of results. CRDM tube WP787. 20% CW325ºC, 35 ccH2/kgH2O, KI= 37 MPa√m

26

MATERIALS DIVISION

CGRs for 20% CW Alloy 690 TT is higher for rolled material than for tensile strained material

0.720.95Average misorientation

18.624.9Equivalent deformation, %

279298Hardness, HV1444557YS (MPa) at 325 ºC

20% CW tensile20% CW rolling

What is the point in comparing “different” materials?What should be the more adequate parameter for comparison?

Discussion

Serco, Ciemat, MHI

C Si Mn P S Cu Cr Ni Fe Al Ti N O Nb+Ta

0.036 0.28 4.24 0.003 0.002 0.01 28.79 Bal. 8.91 0.09 0.08 0.018 0.06 1.46

Chemical Composition of Alloy 152 specimen

360440

230

70

36

Carbon steel

Alloy 152 weld

Weld line 315

PWSCC CGR of Cold Rolled Alloy 152 Weld

Geometry of Alloy 152 specimen

1D Cold

Rolling

(CR:15, 30 and 50%)

SMAW weld

MHI Research Summary

Serco, Ciemat, MHI

Experimental Procedure for Crack Propagation Test

Test piece 0.5T CT

Loading Kmax= 35MPa･m0.5

Initially R=0.7, 0.3hr holding at Kmax

Then R=0.7, 24hr holding at Kmax

Environment 360 Simulated primary waterDO<0.005ppm, DH:30 cc/kgB:1800 ppm Li：3.5 ppm

PWSCC Crack Propagation Test Condition

Serco, Ciemat, MHI

Period CGR(mm/s)I 5.1x10-8

II 5.6x10-9

Specimen 15-01(15% 1D CR)

Crack Extension and Fracture Surface after the Test

Period CGR(mm/s)I 1.1x10-7

II 1.0x10-9

Specimen 15-02(15% 1D CR)

Serco, Ciemat, MHI

Period CGR(mm/s)I 6.1x10-8

II 8.0x10-10

Specimen 30-02(30% 1D CR)

Crack Extension and Fracture Surface after the Test

Period CGR(mm/s)I 2.1x10-8

II 3.0x10-9

Specimen 30-03(30% 1D CR)

Serco, Ciemat, MHI

Period CGR(mm/s)I 1.2x10-7

II 6.3x10-9

III 3.4x10-8

IV 1.0x10-9

Specimen 50-01(50% 1D CR)

Crack Extension and Fracture Surface after the Test

Period CGR(mm/s)I 1.3x10-6

II 7.0x10-8

III 7.1x10-7

IV 2.1x10-7

V 6.9x10-7

VI 2.0x10-7

VII 1.3x10-6

Specimen 50-02(50% 1D CR)

Serco, Ciemat, MHI

CR ratio is one of the dominant factors in CGR.However, CGR scatter is larger than change caused by CR ratio.

• In all specimens, crack extension is local.• Fracture surfaces were investigated to find cause

of the local high CGR.

Discussion

Example of local crack extension

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

0 20 40 60 80 100Cold Rolling Ratio(%)

Cra

ck G

row

th R

ate

CG

R(m

m/s

)

10-10

10-9

10-8

10-7

10-6

10-5

10-4

　K = 35MPa・m0.5

(R=0.7, 24hr holding)　DO＜0.005ppm,　DH＝30 cc/kg　B:1800 ppm,　Li：3.5 ppm

Serco, Ciemat, MHI

200

300

400

500

0 10 20 30 40 50 60Cold Rolling Ratio(%)

Har

dnes

s(H

V0.1

)

Post-test fracture surface locationSCC fracture surface location

No significant difference between hardness of SCC fracture surface and that of post-fracture surface

Serco, Ciemat, MHI

15% 1D CR 30% 1D CR 50% 1D CR

• Interval of fracture surface fringe pattern is proportional to CR ratio.• Therefore, the fringe reflects geometric change in microstructure

caused by CR.• The fringe is estimated to be surface of dendrite secondary arm.

Interval of fringe 33um Interval of fringe 17um Interval of fringe 9um

Discussion: Fracture surface characteristics

Dendrite growth

Fracture surface observation

Thickness reduction by CR

Serco, Ciemat, MHI

MHI Summary

• PWSCC susceptibility of alloy 152 is strongly dependent of microstructure.– In the case of alloy 152 weld, CGR strongly depends on

direction of dendrite growth.

• For alloy 690, CGR depends on grain boundary coherency.• Cold working increases CGR of both alloy 152 & alloy 690.