june 2011. - nuclear regulatory commissionjune 6-7, 2011 bogdan alexandreanu, yiren chen, ken...

Update on SCC CGR tests on Alloys 690/52/152 at ANL – June 2011

Work sponsored by the US Nuclear Regulatory Commission

US NRC/EPRI Meeting

Rockville, MD

June 6-7, 2011

Bogdan Alexandreanu, Yiren Chen, Ken Natesan and Bill Shack

Argonne National Laboratory

2Work sponsored by the US Nuclear Regulatory Commission

Presentation Topics

Experimental approach

SCC of 52M/182 WOL

SCC of Alloy 152 Weld

SCC of Alloy 690 HAZ


Experimental Approach - Transitioning to SCC

ANL approach very similar to the widely-used method (increasing R and decreasing frequency) but with a few differences:

- Precracking is always conducted in the environment1

- Use of slow/fast sawtooth with increasing rise times- Loading takes into account possible K and Kth effects2

- Monitor specimen response- Calculate cyclic CGRs based on rise time3

- Monitor cyclic rates for environmental enhancement 4

- Attempt to transition only from those conditions that showenvironmental enhancement

1 Provides (essential) baseline cyclic data2 K/Kth effects have been observed/formulated for Alloy 6903 Well-characterized cyclic CGR also enables the calculation of the SCC component for periods

with hold times or constant load with periodic unloading4 Accomplished by plotting the measured in the environment vs. the rates that would be

expected in air under the same loading conditions


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

*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


Expected behavior of cyclic rates: Alloys 600, 690, Ni-Alloy Weld

10-11

10-10

10-9

10-8

10-7

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

CGR env 600 (NUREG-4667)CGR air 690 (NUREG-6383)CGR air weld (NUREG-6921)CGR env weld (NUREG-6921)

CG

Ren

v (m

/s)

CGRair (m/s)

CGR env Ni-weld

CGR env 600

CGR air 600

CGR air 690

CGR air Ni-weld

Correlations established at ANL for a variety of alloys Fatigue behavior is highly reproducible


Alloy 52M/182 Weld Overlay

Alloy 182 weld tested previously (without the WOL) Alloy 52M (Special Metals, Heat NX75W1TK ) welded at ANL Central Shops using

parameters used by industry CGR test objective: attempt to transition an SCC crack from Alloy 182 into 52M

Alloy 600

Alloy 182

1

Alloy 52M

18252M


Alloy 52M/182 Weld Overlay – Summary of SCC CGR data vs. distance to the interface

SCC CGRs decrease as the crack approaches the interface, continues to decrease past the interface

Control cyclic rates mirror the SCC behavior

182 52M

10-12

10-11

10-10

10-9

-2.0 -1.0 0.0 1.0 2.0 3.0

8

SCC CGR (CL, CL + pu)est SCC CGR (cycle + hold)Control cycle

CG

R (m

/s)

Distance from the 52M WOL interface (mm)

Alloy 182 Alloy 52M


Alloy 52M/182 WOL – Fracture Surface 1

Partial (40%) growth into Alloy 52M Areas A + B: average growth 0.35 mm, average CGR 3 10-11 m/s

(consistent with DC potential) Area B: max growth 2.5 mm, max CGR 2 10-10 m/s


Alloy 52M/182 WOL – Crack Transition from Alloy 182 to Alloy 52M(region A)

No change in fracture mode at the interface


Alloy 52M/182 WOL – Crack Transition from Alloy 182 to Alloy 52M(region B)

No change in fracture mode at the interface


Alloy 52M/182 Weld Overlay – test in progress (A52M-182-TS-1)

Objective: confirm behavior observed in the previous test 1T CT specimen in similar (TS) orientation, initial notch 8.2 mm from the interface

182

52M



Cyclic rates similar to those obtained previously on the same weld (without the Alloy 52M WOL)

SCC CGR similar approx. 2 mm from the interface

10-12

10-11

10-10

10-9

10-8

10-7

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

A52M-182-TS-1A52M-182-TS-3A182-TS-1

CG

Ren

v (m

/s)

CGRair Ni-weld alloys (m/s)

Alloy 182 WeldSimulated PWR Water at 320°C

Best Fit Curve for Alloy 182CGRair + 0.018 (CGRair)

0.78

10-12

10-11

10-10

10-9

10 15 20 25 30 35 40

A182-TS-1A52M-182-TS-3A52M-182-TS-1

Exp

erim

enta

l CG

R (m

/s)

Stress Intensity K (MPa·m1/2)

Alloy 52M/182 WOL320°C

ProposedDisposition Curve

for Alloy 182 Weld (MRP-115)



SCC CGRs decrease as the crack approaches the interface Error bars: 20% uncertainty in DC potential measurements

10-12

10-11

10-10

10-9

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

8

A52M-182-TS-3 (CL, CL + pu)A52M-182-TS-3 (cycle + hold)A52M-182-TS-1 (CL + pu)

CG

R (m

/s)

Distance from the 52M WOL interface (mm)

Alloy 182 Alloy 52M


Alloy 52M/182 Weld Overlay – key findings and future tests

Substantial growth (0.7 mm) in Alloy 52M in a direction parallel to the interface Crack appearance (branching) suggests an IG fracture mode

Crack propagation First test (A52M-182-TS-3): Interaction with the interface a concern


Alloy 52M/182 WOL – fractured specimen A52M-182-TS-3

Growth along the interface appears more severe than initially thought (based on the cross section): 2.2 mm (3000h), CGR 2 10-10 m/s


Alloy 52M/182 Weld Overlay – dilution specimens

182

52M

152 butter

LAS

CT specimens aligned along the 52M/182 and 152/LAS


Alloy 52M/182 WOL - Summary

Tests were initiated in Alloy 182, and both cyclic and SCC known conditions were reproduced

The 52M/182 interface seems to affect crack propagation in Alloy 182 ahead of the interface:- both SCC CGRs and environmental enhancement of cyclic rates decreased

First completed test (emerging issues):

Alloy 52M is susceptible to IG SCC, CGRs 10-11 m/s (consistent with Alloy 152 in IG fracture mode)

Alloy 52M seems highly susceptible to cracking along the interface (SCC CGRs 10-10 m/s) – the effect of dilution will be addressed in future ANL tests


Alloy 152 Welds

New weld: same Alloy 152 heat WCO4F6 (152, 1/8) as the previous weld Welding procedure was qualified to ASME IX 1-T CT specimens cut in similar fashion, TS orientation Similar CGR testing conditions (320C, 23 cc/kg H)


Alloy 152 Weld specimen N152-TS-1


Alloy 152 specimen N152-TS-1 – in-situ precracking

Objectives: Create a sharp crack tip Confirm the expected fatigue behavior for the specimen

- high frequency (>0.5 Hz) establishes the baseline “air” curve - consistent fatigue data ensures the straightness of the crack front

12.50

13.00

13.50

14.00

14.50

15.00

15.50

16.00

0

20

40

60

80

100 200 300 400 500 600Time (h)

Kmax

Crack Length

Pre a

Pred

Pref

Prej

Prel

Pren

Prer

1Alloy 152Specimen # N152-TS-1PWR environment

Cra

ck L

engt

h (m

m)

Km

ax (M

Pa

m0.

5 )


Alloy 152 specimen N152-TS-1

Known fatigue and corrosion fatigue behavior (analysis based on 129 tests in air and water, NUREG-6921) reproduced, 3x environmental enhancement

R=0.5, 600/12 was chosen as transitioning condition, CGRair 6 10-11 m/s*,close to expected SCC CGR, hence, will preserve IG SCC behavior*at K=30 MPa m1/2, 350°C, CGRair 1.5 10-10 m/s

10-11

10-10

10-9

10-8

10-7

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

N152-TS-1

CG

Ren

v (m

/s)




0.78

10-11

10-10

10-9

10-8

10-7

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

N152-TS-1A152-TS-2A152-TS-4A152-TS-5

CG

Ren

v (m

/s)




0.78



Ligaments pose a problem early on (good news) CL + PU (either 2h or 1h) too gentle Start and end by reproducing known conditions IG SCC fracture mode is suspected – must be preserved (use R=0.5, 600/12 )

16.20

16.25

16.30

16.35

16.40

0

20

40

60

80

2200 2400 2600 2800 3000Time (h)

Kmax

Crack Length

Period 91.5 x 10–11 m/s26.3 MPa m0.5

R=0.5, 600/12, 2h hold

Period 101.5 x 10–11 m/s26.3 MPa m0.5

R=0.5, 600/12, 1h hold

Period 114.0 x 10–12 m/s26.3 MPa m0.5

CL + PU (2h)

Period 122.6 x 10–12 m/s26.3 MPa m0.5

CL + PU (1h)

Period 131.2 x 10–10 m/s26.8 MPa m0.5

R=0.5, 600/12

Alloy 152Specimen # N152-TS-1PWR environment

Period 81.45 x 10–10 m/s26.6 MPa m0.5

R=0.5, 600/12



Period 14: average SCC CGR component 4.6 10-11 m/s(cycle + hold is actually gentler than CL + PU)

16.30

16.35

16.40

16.45

16.50

16.55

0

20

40

60

80

100

3000 3100 3200 3300 3400 3500 3600 3700Time (h)

Kmax

Crack Length

Period 131.2 x 10–10 m/s26.8 MPa m0.5

R=0.5, 600/12

Period 142.5 x 10–11 m/s26.8 MPa m0.5

R=0.5, 600/12, 2h hold

6.5 x 10–11 m/s

5.4 x 10–11 m/sAlloy 152Specimen # N152-TS-1PWR environment



Previous rate confirmed at CL in test period 15 Ligaments begin to affect the crack length readings Reintroduced cycle – note the lag

16.45

16.50

16.55

16.60

16.65

15

20

25

30

3500 3600 3700 3800 3900 4000Time (h)

Kmax

Crack Length

Period 154.3 x 10–11 m/s26.8 MPa m0.5

CL

Period 145.4 x 10–11 m/s

R=0.5 600/12+ 2h

Period 161.6 x 10–10 m/s27.1 MPa m0.5

R=0.5, 600/12




Attempt CL + PU (either 2h or 1h) - too gentle Start and end by reproducing known conditions (and preserve the fracture

mode)

16.50

16.55

16.60

16.65

16.70

16.75

16.80

20

30

40

50

60

3900 4000 4100 4200 4300 4400 4500Time (h)

Kmax

Crack Length

Alloy 152Specimen # N152-TS-1PWR environment Period 18

1.7 x 10–10 m/s27.3 MPa m0.5

R=0.5, 600/12Period 17negligible

27.1 MPa m0.5

CL + PU (2h)

Period 191.4 x 10–11 m/s27.3 MPa m0.5

CL + PU (2h)

Period 20negligible

27.3 MPa m0.5

CL + PU (1h)

Period 161.6 x 10–10 m/s27.1 MPa m0.5

R=0.5, 600/12

Period 211.2 x 10–10 m/s27.4 MPa m0.5

R=0.5, 600/12



SCC CGR consistent with those measured previously

16.65

16.70

16.75

16.80

16.85

20

30

40

50

60

4500 4600 4700 4800 4900 5000 5100 5200Time (h)

Kmax

Crack Length

Period 222.5 x 10–11 m/s27.4 MPa m 0.5

CL


Period 211.2 x 10–10 m/s27.4 MPa m 0.5

R=0.5, 600/12


The Analysis of Cyclic CGR Data for Alloy 152 –Implications for the SCC test management

10-13

10-12

10-11

10-10

10-9

10 20 30 40 50

A152-TS-2A152-TS-4A152-TS-5

Exp

erim

enta

l CG

R (m

/s)


Alloy 152 Weld320°C

MRP-115 Ni-Weds

75 Percentile

MRP-115Ni-Welds

25 Percentile

y = m1 * (M0)^ 1.6ErrorValue

1.0815e-148.7892e-14m1 NA5.835e-22ChisqNA0.37161R

env air CF SCCa a a a

Need to balance the need for environmental enhancement with the optimal test condition (to measure SCC), keeping in mind the effects of R and rise time

Expected curve for the total CGR in the environment very close to the CF curve – quality mechanical and CF data for the alloy at hand becomes critical

R=0.7

R=0.5

R=0.3

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 10-6

CG

Ren

v (m

/s)




0.78

K = 28 MPa·m1/2


The Analysis of Cyclic CGR Data – Alloy 152env air CF SCCa a a a

Larger K (50 MPa m1/2) would certainly help, however, The need for quality mechanical and CF data for the alloy at hand remains

important

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 10-6

CG

Ren

v (m

/s)




0.78

K = 50 MPa·m1/2


Alloy 152 - Summary

Test in progress on the new weld:

Known fatigue and corrosion fatigue behavior were reproduced

Select loading conditions show environmental enhancement of cyclic CGRs

The SCC CGRs in simulated PWR water at 320C appear to be in the 10-11 m/s, consistent with previous results


CRDM Alloy 690 HAZ

Alloy 152 Weld (B-P7)specimen designation C152

Alloy 690 HAZ (2541-Heat WP142, Valinox) specimen designation CF690-CR-XX

Two specimens CF690-CR-1 and CF690-CR-3: test plane parallel to the HAZ


CF690-CR-1 Lateral surface 1

Crack seems to follow the fusion line Granular fracture mode


CRDM Alloy 690 HAZ

Alloy 152 Weld (B-P7)specimen designation C152

Alloy 690 HAZ (2541-Heat WP142, Valinox) specimen designation CF690-CR-XX

Current approach: test plane at an angle to the HAZ


CRDM Alloy 690 HAZ Specimen CF690-CR-3

Constant load with periodic unloading (2 h) CGR 9 10-12 m/s initially On average, CGR factor 2x higher than that for the alloy in the as-received

condition

11.930

11.940

11.950

11.960

11.970

0

10

20

30

40

50

60

70

80

400 600 800 1000 1200Time (h)

Alloy 690 HAZSpecimen # CF690-CR-4PWR environment

Kmax

Crack Length

Period 46.0 x 10–12 m/s21.8 MPa m0.5

Constant Load with PU (2h)

Cra

ck L

engt

h (m

m)

Km

ax (M

Pa

m0.

5 )8.7 x 10–12 m/s

3.2 x 10–12 m/s

Period 52.6 x 10–11 m/s21.8 MPa m0.5

R=0.5, 600/12

Period 38.3 x 10–11 m/s21.7 MPa m0.5

R=0.5, 600/12


Cyclic CGRs for Alloy 690 HAZ vs. as-received and 26%-CR

Cyclic rates for the third specimen consitent with those measured previously; the new approach shows some promise

Environmental enhancement for Alloy 690 HAZ is similar to that for the as-received alloy Cyclic rates for Alloy 690 HAZ specimens are smaller than those for 26%-CR alloy

10-12

10-11

10-10

10-9

10-8

10-7

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

26% CR, A690WC-SL-126% CR, A690WC-ST-1C690-CR-1CF690-CR-1CF690-CR-3

CG

Ren

v (m

/s)

CGRair (m/s)

Alloy 690Simulated PWR Water at 320°C

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

0.33

10-12

10-11

10-10

10-9

10-8

10-7

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

CF690-CR-1CF690-CR-3CF690-CR-4

CG

Ren

v (m

/s)

CGRair (m/s)

Alloy 690 HAZSimulated PWR Water at 320°C

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

0.33

3

5


Cyclic CGR data for Alloy 690 HAZ vs. Ni-base Welds

Cyclic CGRs are consistent with Alloy 690 (and not the weld) Fatigue and corrosion fatigue data for the alloys of interest (152/52/52M) and in

the orientation of interest would be very useful

10-12

10-11

10-10

10-9

10-8

10-7

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

CF690-CR-1CF690-CR-3CGR air weld (NUREG-6921)CGR env weld (NUREG-6921)

CG

Ren

v (m

/s)

CGRair (m/s)

Alloy 690 HAZSimulated PWR Water at 320°C

CGR air Ni-weld

CGR env Ni-weld

10-12

10-11

10-10

10-9

10-8

10-7

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

CF690-CR-1CF690-CR-3CGR air weld (NUREG-6921)CGR env weld (NUREG-6921)

CG

Ren

v (m

/s)

CGRair (m/s)

Alloy 690 HAZAir at 38°C

CGR air Ni-weld

CGR env Ni-weld


SCC CGRs vs. K for Alloy 690 HAZ

Good agreement between CGRs at constant load (solid) and CGRs determined from cyclic loading

Overall, HAZ CGRs are similar or only slightly higher than those for the as-received alloy Last test: CGR factor 2x higher than that for the alloy in the as-received condition

10-13

10-12

10-11

10-10

10-9

10 15 20 25 30 35 40 45 50

ANL C690-CR-1 (23 cc/kg)ANL C690-LR-2 (23 cc/kg)CF690-CR-1 (A690 HAZ)CF690-CR-3 (A690 HAZ)CF690-CR-4 (A690 HAZ)

Exp

erim

enta

l CG

R (m

/s)


Alloy 690HAZSimulated PWR environment320°C, 23 cc/kg H2 CGR Curve Alloy 600

75th Percentile

CGR Curve Alloy 60050th Percentile


Alloy 690 HAZ future tests CRDM Alloy 690 HAZ testing will continue (attractive because cyclic and

SCC data in the base alloys already exists) New Alloy 690 HAZ specimens from the new weld:

combined effect of HAZ (+ banding)

Alloy 690 plate Heat NX3297HK12 (ATI Wah Chang)Alloy 533-Gr B Heat A5401 (Midland reactor lower head)Alloy 152 Heat WC0F6 (Special Metals)


Alloy 690 HAZ - Summary

The cyclic CGRs of Alloy 690 HAZ appear to shows only slight difference vs. as-received Alloy 690

The SCC CGRs for Alloy 690 HAZ appear to be only slightly higher that those for the as-received condition tested

Fracture mode of Alloy 690 HAZ:- appears to depend on the proximity to the fusion line (1st test)- predominantly TG, with granular appearance (dendritic features – 1st test), TG facets, IG secondary cracks near the fusion line- new approach (fracture surface at an angle vs. fusion line) in progress

Overall, both cyclic and SCC seem to be controlled by Alloy 690 in the as-received condition (TG)

june 2011. - nuclear regulatory commissionjune 6-7, 2011 bogdan alexandreanu, yiren chen, ken...

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