Presentation Slides: SCC CGRs of Alloys 690 and 152 Weld ... · aa a a env air CF SCC=+ + SCC ref...
Transcript of Presentation Slides: SCC CGRs of Alloys 690 and 152 Weld ... · aa a a env air CF SCC=+ + SCC ref...
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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
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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
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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
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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
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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
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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
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Results - Alloy 690 specimen A690WC-SL-1
13.00
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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
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Results - Alloy 690 specimen A690WC-ST-1
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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
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Fracture surface of A690WC-SL-1
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Fracture surface of A690WC-ST-1
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Fracture surface of A690WC-SL-1
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Fracture surface of A690WC-SL-1
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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
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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
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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
CGR Curve Alloy 60050th Percentile α
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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
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10-11
10-10
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10 15 20 25 30 35 40 45 50
Exp
erim
enta
l CG
R (m
/s)
Stress Intensity K (MPa·m1/2)
Alloy 690 VIM plate, CR325°C
CGR Curve Alloy 60075th Percentile α
CGR Curve Alloy 60050th Percentile α
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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”
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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
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Alloy 152 Specimens (A152-TS-2 and A152-TS-4)
A152-TS-4 test in progress
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Alloy 152 specimen A152-TS-2
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ck L
engt
h (m
m)
K max
(MP
a m
0.5 )
Time (h)
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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
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Fracture surface of A152-TS-2
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ck L
engt
h (m
m)
K max
(MP
a m
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Time (h)
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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
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Fracture surface of A152-TS-2
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SCC CGRs for A152 and Alloy 182 vs. K
A152-TS-4 rates are not corrected
10-12
10-11
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CT31-W01 Double-JCT933-01 Deep GroveCT31-W02 Double-JCT933-TL1CT933-LSA152-TS-2A152-TS-4
Exp
erim
enta
l CG
R (m
/s)
Stress Intensity K (MPa·m1/2)
Ni-Alloy Weld Metal320°C
CGR CurveNi-Welds
CGR CurveNi-Welds
25 Percentile
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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
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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
CGRair + 0.018 (CGRair)0.78
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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
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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
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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
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CGR testing of CRDM Alloy 690
CRLR
LR
CR
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CGR testing of Alloys 690, Alloy 690 HAZ and Alloy 152 Weld
Alloy 690 HAZCL, CR
Alloy 152 Weld (B-P7)CR, LR
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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)
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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)
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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
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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
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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
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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
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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
CGRair + 0.018 (CGRair)0.78
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
![Page 32: Presentation Slides: SCC CGRs of Alloys 690 and 152 Weld ... · aa a a env air CF SCC=+ + SCC ref Q1 1 aexp K RT T ... Presentation Slides: SCC CGRs of Alloys 690 and 152 Weld in](https://reader034.fdocuments.in/reader034/viewer/2022042710/5f60741d3dc4e60d9a38b426/html5/thumbnails/32.jpg)
32Work sponsored by the US Nuclear Regulatory Commission
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)