presentation slides: scc cgrs of alloys 690 and 152 weld ... · aa a a env air cf scc=+ + scc ref...

SCC CGRs of Alloys 690 and 152 Weld in PWR Water

Work sponsored by the US Nuclear Regulatory Commission

EPRI Expert PanelNovember 8-9, 2007

Bogdan Alexandreanu, Omesh Chopra, and Bill ShackNuclear Engineering DivisionArgonne National Laboratory, Argonne, IL 60439

2Work sponsored by the US Nuclear Regulatory Commission

Outline

CGR of Alloy 690- comparison with data reported by Bettis (similar alloy condition,and similar deformation levels)

CGR of Alloy 152 Weld- comparison with Alloy 182

Future work

Possible discussion topic– transitioning to SCC


Experiment

Temp: 320°C PWR Water (<10 ppb DO, 1000 ppm B, 2 ppm Li, ≈23 cc/kg hydrogen)Flow Rate: ≈55 mL/minConductivity: ≈20 µS/cmLoading history to facilitate the transition from transgranular fatigue cracking to intergranular SCC cracking:

- Precracking carried out in the PWR environment - Load Ratio R: 0.3–precrack;

0.5-0.7–sawtooth with up to 1000s rise time; 1.0–constant load


The Analysis of Cyclic CGR Data∗

Superposition model (Kassner & Shack)

( )0.78air CF air aira a a 0.018 a+ = + ⋅

env air CF SCCa a a a= + +

SCCref

Q 1 1a exp KR T T

β⎡ ⎤⎛ ⎞= α − −⎢ ⎥⎜ ⎟

⎢ ⎥⎝ ⎠⎣ ⎦

For Ni-welds:

10-12

10-11

10-10

10-9

10-8

10-7

10-6

10-12 10-11 10-10 10-9 10-8 10-7 10-6C

GR

env

CGRair

CGRair + 0.018 (CGRair)0.78

∗ Example shown is for Ni-alloy welds, the approach for Alloy 690 is similar


Alloy 690 Specimens

<0.010.010.4730.8259.670.040.020.0030.0018.530.330.04ANL

29.559.50.010.07<0.0019.90.200.03VendorA 690WC (NX3297HK12)

CoNbTiCrNiCuSiPSFeMnCAnalysisAlloy ID (Heat)

Alloy 690 in plate form (MIL-DTL-24802∗)

Cold-rolled in three passes to achieve approx. 26% reduction in thicknessSpecimens cut in both SL and ST orientations

Approx 1.5”

3.5”

17”

rolling direction

1 2 3 4

∗MIL-DTL-24802- vacuum induction - melted - electro slag - removed - hot - rolled - de-scaled- annealed at 1900F for 2h- air-cooled


Results - Alloy 690 specimen A690WC-SL-1

13.00

13.20

13.40

13.60

13.80

14.00

10

20

30

40

50

60

70

80

400 800 1200 1600 2000 2400 2800

Cra

ck L

engt

h (m

m)

K max

(MP

a m

0.5 )

Time (h)

Alloy 690Specimen # A690WC-SL-1320°C, Simulated PWR Water

71.46 x 10–11 m/s26.7 MPa m0.5

Constant Load

63.63 x 10–10 m/s26.2 MPa m0.5

0.50, Rise time = 1000 s

Kmax

8

10

Crack Length

92.83 x 10–11 m/s28.0 MPa m0.5

Constant Load

Crack lengthKmax


Results - Alloy 690 specimen A690WC-ST-1

13.00

13.20

13.40

13.60

13.80

14.00

14.20

14.40

20

25

30

35

40

45

50

55

60

2600 2800 3000 3200 3400 3600 3800 4000

Cra

ck L

engt

h (m

m)

Km

ax (M

Pa

m0.

5 )

Time (h)

Kmax

Crack Length

Alloy 690Specimen # A690WC-ST-1320°C, Simulated PWR Water

12

Period 133.3 x 10–11 m/s31 MPa m0.5

Constant Load


Fracture surface of A690WC-SL-1


Fracture surface of A690WC-ST-1


Bettis: SL orientation is very high (comparable to Davis-Besse Nozzle #3 Alloy 600)Bettis: SCC CGRs are higher for 50 cc/kg than for 23 cc/kg of hydrogenANL data: no apparent difference between the SL and ST orientationsANL and Bettis agreement (where hydrogen level was also the same, 23 cc/kg )

SCC CGRs for Alloy 690 vs. K

10-12

10-11

10-10

10-9

10 15 20 25 30 35 40 45 50

ANL DB N3CC-2ANL DB N3CC-3ANL 26%CR A690WC-SL-1 (23 cc/kg)ANL 26% CR A690WC-ST-1 (23 cc/kg)Bettis 24% CR ST (50 cc/kg)Bettis 24% CR Bettis 24% CR SL (50 cc/kg)Bettis 24% CR ST (23 cc/kg)Bettis 24% CR SL (23 cc/kg)

Also included is data from Davis-Besse Nozzle #3 Alloy 600Bettis data obtained on similar VIM plate, 24% CR obtained at 338°C (normalized using Q = 130 kJ/mol)

10-12

10-11

10-10

10-9

10 15 20 25 30 35 40 45 50

Exp

erim

enta

l CG

R (m

/s)

Stress Intensity K (MPa·m1/2)

Alloy 600 from Davis-Besse and Alloy 690325°C

CGR Curve Alloy 60075th Percentile α



SCC CGRs for Alloy 690 vs. K

Good agreement with Bettis data at the same hydrogen level (23 cc/kg)

10-12

10-11

10-10

10-9

10 15 20 25 30 35 40 45 50

ANL 26%CR A690WC-SL-1 (23 cc/kg)ANL 26% CR A690WC-ST-1 (23 cc/kg)Bettis 24% CR ST (23 cc/kg)Bettis 24% CR SL (23 cc/kg)Bettis 32% prestrain SLBettis 32% prestrain ST

10-12

10-11

10-10

10-9

10 15 20 25 30 35 40 45 50

Exp

erim

enta

l CG

R (m

/s)


Alloy 690 VIM plate, CR325°C




Cyclic CGR data for 26% Cold-Rolled Alloy 690 and Davis-Besse Alloy 600

Alloy 690 cold-rolled shows significant environmental enhancement(transitioning to SCC was expected)Good agreement with Davis-Besse Nozzle #3 Alloy 600 dataConsistent with Bettis observation of “no incubation time”

10-11

10-10

10-9

10-8

10-7

10-11 10-10 10-9 10-8 10-7

1/2-T CT DB N3CC-31/4-T CT DB N3CL-11/4-T CT DB N3CC-2A690WC-SL-1A690WC-ST-1

CG

Ren

v (m

/s)

CGRair (m/s)

Alloy 690 and Davis-Besse N#3 Alloy 600Simulated PWR Water

Best-Fit Curve for Davis-Besse N#3 A600CGRair + 6.6 x 10–7(CGRair)

0.33


Alloy 152 Specimens (A152-TS-2 and A152-TS-4)

A152-TS-4 test in progress


Alloy 152 specimen A152-TS-2

16.00

16.50

17.00

17.50

18.00

20

25

30

35

40

800 1000 1200 1400 1600 1800

Cra

ck L

engt

h (m

m)

K max

(MP

a m

0.5 )

Time (h)

Kmax

Crack Length

Alloy 152 SMA Double–J WeldSpecimen # A152-TS-2320°C, Simulated PWR Water 4

5.7 x 10–11 m/s30.2 MPa m0.5

Constant load

Inte

rmitt

ent

pow

er s

witc

h / p

ump

Crack lengthKmax


Fracture surface of A152-TS-2

11.2

12.0

12.8

13.6

14.4

15.2

16.0

16.8

17.6

15

20

25

30

35

40

50 100 150 200 250

Cra

ck L

engt

h (m

m)

K max

(MP

a m

0.5 )

Time (h)

Kmax

Crack Length

Alloy 152 SMA Double–J WeldSpecimen # A152-TS-2320°C, Simulated PWR Water

Prea

Preb

Prec

Pred

Pree

Pref

Preg

Preh

Prei

Prej

Prek

1

Crack lengthKmax


Fracture surface of A152-TS-2


SCC CGRs for A152 and Alloy 182 vs. K

A152-TS-4 rates are not corrected

10-12

10-11

10-10

10-9

10 15 20 25 30 35 40 45 50

CT31-W01 Double-JCT933-01 Deep GroveCT31-W02 Double-JCT933-TL1CT933-LSA152-TS-2A152-TS-4

Exp

erim

enta

l CG

R (m

/s)


Ni-Alloy Weld Metal320°C

CGR CurveNi-Welds

CGR CurveNi-Welds

25 Percentile


Cyclic CGR data for Alloy 152 Weld

A152-TS-4 rates are not correctedConditions selected for transitioning from TG to IG SCC appear to be critical

10-12

10-11

10-10

10-9

10-8

10-7

10-12 10-11 10-10 10-9 10-8 10-7

A152-TS-2

A152-TS-4

CG

Ren

v (m

/s)

CGRair Ni-weld alloys (m/s)

Alloy 152 WeldSimulated PWR Water at 320°C



Summary of Testing Results

Fracture surfaces were uniform for both Alloy 690 and 152 specimens;the experimental approach facilitated transitioning to SCC

The cyclic CGRs of cold-rolled Alloy 690 show significant environmental enhancement

The environmental enhancement of cyclic CGRs is minimal for Alloy 152

The SCC CGRs in simulated PWR water at 320°C were as high as: 2.8-3.3 x 10-11 m/s for Kmax = 28-31 MPa m1/2 for Alloy 6905.4 x 10-11 m/s for Kmax = 30.2 MPa m1/2 for Alloy 152


Future Work - Objectives

1. Determine the SCC CGR for Alloys 690, Alloy 690 HAZ, and Alloy 152/52 Welds

2. Determine the activation energy for SCC CGR for Alloys 690, Alloy 690 HAZ, and 152/52 Weld


Future Work – Alloys

Alloy 690 on hand:1. Alloy 690 in plate form (including 26% cold rolled, Wah Chang)2. 20% cold-rolled Alloy 690 in plate form (exchange with Peter Andresen, GE)3. CRDM Alloy 690TT (2 tubes); 2941-Heat WP142, Valinox Nucleaire also used

for Alloy 690 HAZ testing

Alloy 152 on hand:1. Double-J weld mock-up (ANL), currently used in CGR tests, also used for

tensile testing vs. temperature2. B-P7 Alloy 152 weld on CRDM Alloy 690TT (2941-Heat WP142, Valinox

Nucleaire)

Planned: 1. Double-V weld mock-up 690/152/LAS, also for aging studies 2. CRDM Alloy 690 tube /152(52)/Alloy 690 plate mock-up


CGR testing of CRDM Alloy 690

CRLR

LR

CR


CGR testing of Alloys 690, Alloy 690 HAZ and Alloy 152 Weld

Alloy 690 HAZCL, CR

Alloy 152 Weld (B-P7)CR, LR


Approach

Use CGR testing in simulated primary water- precracking conducted in the environment- loading sequence to facilitate transition from fatigue TG to SCC IG - monitor cyclic CGR for environmental enhancement

The approach results in uniform SCC engagement and straight crack fronts)


Significant Milestones

Complete CGR tests on CRDM nozzle Alloy 690TT as a function of orientation in PWR water (12/08)

Provide an interim report detailing the experimental results from the crack growth rate testing of Alloy 690 and Alloy 152. (04/09)

Milestones for FY 2010 Complete CGR tests on Alloy 690TT in PWR water to determine the activation energy for PWSCC. (11/09)Complete CGR tests on Alloy 690TT HAZ material as a function of loading and temperature in PWR water.

(06/10)

Milestones for FY 2011 Complete CGR tests on CRDM nozzle Alloy 152 weld as a function of orientation. (11/10)Complete CGR tests on Alloy 152 weld to determine activation energy for PWSCC (08/11)

Conclude CGR tests on Alloy 690 and Alloy 152. Provide a final NUREG/CR report describing the results of the crack growth rate testing of Alloy 690 and Alloy 152. (09/11)


Possible Discussion Point: Transitioning to SCC

Transitioning to SCC– Widely-used method: increasing R and decreasing frequency– ANL approach very similar, but with a few differences:

- precracking in the environment- use of slow/fast sawtooth with increasing rise times- calculate cyclic CGRs based on rise time∗

- monitor cyclic rates for environmental enhancement

∗Well-characterized cyclic CGR also enables the calculation of the SCC component for periods with hold times or periodic unloading

Focus on cyclic CGRs


Effect of Increasing R on Cyclic CGRs

Cyclic CGRs depart from “sustained EAC condition” beyond at R ≥ 0.85

David Tice, 2007 PVP: Wrought 304L and 308L SSs in PWR water at 250°C


Effect of Hold Time on Cyclic CGRs

Cyclic CGRs at R = 0.7-0.8 depart from “sustained EAC condition” when hold times are introduced (especially in the 10-11-10-10 m/s range)

David Tice, 2007 PVP: Wrought 304L SS in PWR water at 300°C


Trends for Cyclic CGR data for Alloys 690/152

Cold-rolled Alloy 690 shows significant enhancement; as-received?Alloy 152 shows similar trends to D. Tice’s data

10-12

10-11

10-10

10-9

10-8

10-7

10-12 10-11 10-10 10-9 10-8 10-7

A152-TS-2

A152-TS-4

CG

Ren

v (m

/s)

CGRair Ni-weld alloys (m/s)

Alloy 152 WeldSimulated PWR Water at 320°C


10-11

10-10

10-9

10-8

10-7

10-11 10-10 10-9 10-8 10-7

A690WC-SL-1, 320C (23 cc/kg)A690WC-ST-1,320C (23 cc/kg)A690WC-ST-2, 350C (50 cc/kg)

CG

Ren

v (m

/s)

CGRair (m/s)

26% CR Alloy 690Simulated PWR Water

Best-Fit Curve for Alloy 600CGRair + 4.4 x 10–7(CGRair)

0.33


Implications for CGR testing of Alloys 690/152

Environmentally-enhanced cyclic rates enable transitioning to an SCC fracture mode (ANL experience)

Not all high R – low frequency conditions appear to lead to environmentally enhanced CGRs

– true for Alloy 152 Weld– has to be determined for as-received Alloy 690

Need to monitor cyclic rates to determine environmentally-enhancedconditions (especially important for alloys difficult to crack)

presentation slides: scc cgrs of alloys 690 and 152 weld ... · aa a a env air cf scc=+ + scc ref...

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