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1015 Ni EAF Testing
	ML18267A097
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Issue date:	09/24/2018
From:	Robert Tregoning; NRC/RES/DE
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ML18267A083	List: ML18267A084; ML18267A085; ML18267A086; ML18267A087; ML18267A088; ML18267A089; ML18267A090; ML18267A091; ML18267A092; ML18267A093; ML18267A094; ML18267A095; ML18267A096; ML18267A097; ML18267A098; ML18267A099; ML18284A024;
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Non-Isothermal EAF Testing for 316 Stainless Steel in Simulated PWR Environment Seiji Asada Mitsubishi Heavy Industries, Ltd.

Gary Stevens Technical Executive, EPRI EAF Research and Related ASME Activities, NRC Public Meeting September 25, 2018

Outlines Objectives Experimental Procedure Test Condition Test Matrix Comparison of Experimental Fatigue Lives and Predictions Measurement of Crack Growth Rate Beachmark Observation Extended WKR Method to Non-Isothermal Condition Conclusions 2

Objectives In November 2012, EPRI gap report, Environmentally Assisted Fatigue Gap Analysis and Roadmap for Future Research, Roadmap, 1026724, Final Report was issued.

Gap 15 Non-Isothermal S-N Testing

- Limited data available on the influence of variable temperature and variable strain rate within test cycles and of the influence of out-of-phase variations of temperature and strain rate

- Influence of in-phase and out-of-phase temperature and strain variations to be identified by comparison with isothermal tests.

- Austenitic stainless steels in PWR environmental are highest priority Non-isothermal & isothermal testing has been performed to address Gap 15.

3

Experimental Procedure Water Environment Specimen Simulates PWR primary water 6

500 ppm H3BO3 as B 2 ppm LiOH as Li.

Induction Dissolved oxygen (DO) :< 0.005 ppm heater Dissolved hydrogen (DH) : 30 cc/kg H2O GL(24mm) R20 30 Material 160 12 Type 316 Stainless Steel Extensometer C Si Mn P S Ni Cr Mo T/C (GL : 24mm) Min 10.00 16.00 2.00 17 Max 0.08 1.00 2.00 0.045 0.030 14.00 18.00 3.00 Heat 0.04 0.61 0.92 0.038 0.001 10.22 16.86 2.06 26 20 (Note) Average grain size: 30 m (Aqua regia liquid for 10 s) 4

Test Condition Out of phase (NI2-1)

Strain Rate: Slow-Fast Out of phase (NI2-4)

Strain Rate: Fast-Fast

[Out-of-Phase] [In-Phase]

Isothermal fatigue test & Non-isothermal fatigue test Fast a a Temp.(ºC) 325 0.6 Temperature: 100325 ºC. 2 3 Strain (%)

Strain amplitude (a): 0.6 % 100 1 2 1 2 3 1 3 The period t1, t3, t3 and strain rate 1, 2, 3 are parameters. 2 1 Fast Time 3

Fast 0.6 t1=600 sec

- I1-1~4 Slow t2=480 sec Isothermal(I) tests with strain change patterns of Slow-Fast and Fast -Fast t3=1000 sec

[addressed to positive strain rate changes]

- NI2-1~4 Non-Isothermal(NI) tests with strain change patterns of Slow-Fast and Fast -Fast

- NI3-1 Non-isothermal test with very high strain rate in compression (Very Fast-Fast)

- NI4-1 Non-isothermal test with the same condition of NI2-1 adding beach marking Measure crack shape for fatigue life 5

Test Matrix Temp. Strain Temp. Strain rate Period (sec) Strain rate (%/sec No amp. change change

() (%) Pattern Pattern t1 t2 t3 I1-1 100 0.60 Constant Slow-fast 600 480 1000 0.001 0.0025 0.0006 I1-2 325 0.60 Constant Slow-fast 600 480 1000 0.001 0.0025 0.0006 I1-3 100 0.60 Constant Fast-fast 600 480 1000 0.001 0.0025 0.0006 I1-4 325 0.60 Constant Fast-fast 600 480 1000 0.001 0.0025 0.0006 Out of NI2-1 100-325 0.60 Slow-fast 600 480 1000 0.001 0.0025 0.0006 phase NI2-2 100-325 0.60 In-phase Slow-fast 600 480 1000 0.001 0.0025 0.0006 NI2-3 100-325 0.60 In-phase Fast-fast 600 480 1000 0.001 0.0025 0.0006 Out of NI2-4 100-325 0.60 Fast-fast 600 480 1000 0.001 0.0025 0.0006 phase NI3-1 100-325 0.60 Out of phase Very fast-fast 600 480 30 0.001 0.0025 0.02 Out of NI4-1 100-325 0.60 Slow-fast 600 480 1000 0.001 0.0025 0.0006 phase 6

Comparison of Experimental Fatigue Lives and Predictions Non-Isothermal Non-Isothermal Non-Isothermal Non-Isothermal Non-Isothermal Isothermal Isothermal Isothermal Isothermal Out-of-Phase In-Phase In-Phase Out-of-Phase Out-of-Phase I1-1 I1-2 I1-3 I1-4 NI2-1&NI4-1 NI2-2 NI2-3 Temp NI2-4 NI3-1 Temp Temp Temp Temp Temp Temp Temp Strain Temp Strain Strain Strain Strain Strain Strain Strain Strain 10000 Prediction by Draft NUREG/CR-6909 Rev.1 Prediction by JSME S NF1-2009 Experimental Fatigue life Fatigue Life in PWR environment 1000 Factor of 2 with respect to NUREG 100 I1-1 I1-2 I1-3 I1-4 NI2-1 NI2-2 NI2-3 NI2-4 NI3-1 NI4-1 Isothermal Condition Non-Isothermal Condition 7

Comparison of Experimental Fatigue Lives and Predictions (continued)

Considering the characteristic of the used material 1.2 1.E+04 mean Predicted Life with factor (x0.52) (cycles)

Prediction by Draft NUREG/CR-6909 Rev.1 Austenitic SS Prediction by JSME S NF1-2009 Draft NUREG CR6909 Rev.1 factor of 2 1

Expressions factor of 2 0.77 for JSME 0.8 [I1-1] 100 ºC Constant Slow-fast Nleak/Nwp

[I1-2] 325 ºC Constant Slow-fast 0.6 0.52 for Draft NUREG 1.E+03 [I1-3] 100 ºC Constant Fast-fast 0.4 [I1-4] 325 ºC Constant Fast-fast

[NI2-1] 100-325 ºC Out of phase Slow-fast 0.2 [NI2-2] 100-325 ºC In-phase Slow-fast

[NI2-3] 100-325 ºC In-phase Fast-fast 0

I1-1 I1-2 I1-3 I1-4 [NI2-4] 100-325 ºC Out of phase Fast-fast 1.E+02 1.E+02 1.E+03 1.E+04 [NI3-1] 100-325 ºC Out of phase Slow-fast Experimental Life (cycles) [NI4-1] 100-325 ºC Out of phase Slow-fast The experimental fatigue lives of non-isothermal conditions showed longer fatigue lives than the predictions.

8

Measurement of Crack Growth Rate Typical striation widths were measured and da/dN data were obtained.

da/dN of the isothermal tests show the dependency on temperature da/dN of the non-isothermal tests are close to that of 100 ºC isothermal tests.

I1-1 Constant Slow-fast 100 1.E+00 I1-2 Constant Slow-fast 325 I1-3 Constant Fast-fast 100 I1-4 Constant Fast-fast 325 NI2-1 Out of phase Slow-fast 325100 NI2-2 In phase Slow-fast 100325 1.E-01 NI2-3 In phase Fase-fast 325100 NI2-4 Out of phase Fast-fast 100325 NI3-1 Out of phase Slow-fast 325100 Striation width NI4-1 Out of phase Slow-fast 325100

da/dN (mm/cycle) 1.E-02

1.E-03 1.125

1 1.E-04 0.01 0.1 1 Crack Depth, a (mm) 9

Beachmark Observation of NI4-1 The 4th beachmark was identified, but the 1st beachmark could not be found.

The 2nd and 3rd beachmarks could be identified only a few portion, and so the crack depths are estimated.

Multiple crack coalescence may have been occurred around the 2nd to 3rd beachmarks.

3 (No.1)

Calculated by Best Fitting Crack depth, a [mm]

2 1

(No.2)

(No.3) (No.4) 0.2 0

0 0.2 0.4 0.6 0.8 1 Fatigue life ratio, N /Nleak 10

Extended WKR Method to Non-Isothermal Condition JPN PJ (*2)

Kamaya et al.(*1)proposed stress intensity factor

() =

The stress intensity factor range (K) is transformed into the apparent effective strain intensity factor range (K(eff))

by the following equation. By using K(eff), da/dN can be predicted. 1.E-01

JPN Project

()

= 100°C 0.6% 0.004%/s.

325°C 0.6% 0.004%/s 100°C 0.6% 0.4%/s

Next, the relations between measured da/dN and K(eff) 325°C 0.6% 0.4%/s Isothermal Tests Measured da/dN (mm/cycles) from the Japanese project data(*2) and I1-1~4 for isothermal I1-1(100°C)

I1-2(325°C) testing by hollow specimens, of which material, strain rate 1.E-02 I1-3(100°C) and temperature condition are identified, are compared I1-4(325°C) with the above correlation between da/dN and K(eff).

Because of plastic region, specimen shape, aspect ratio and so on, these prediction was not consist with measured 1.E-03 da/dN and should be corrected.

Dcp is defined as the plastic correction factor. Then K(eff) Dcp=0.628 can be converted to K(eff) +2

() = () = 1.E-04 1.E-04 2 1.E-03 1.E-02 1.E-01

1: Kamay, M., PVP2016-63434, ASME, 2016.

Analysis da/dN (mm/cycles)

2: JNES, Report on Environmental Fatigue Tests of Nuclear Power Plant Materials for 11 Reliability Verification [General Version] 2006FY

Extended WKR Method to Non-Isothermal Condition (continued) 500 1 The WKR method is extended to non-isothermal condition. 450 400 NI2-1 Out-of-phase Slow-Fast 100-325 N=1 0.8 0.6 350 0.4 Temperature ()

300 0.2 Strain (%)

250 0 200 -0.2 150 -0.4 100 -0.6 2516 Temp. exp ; 150 343 50 Water temperature Strain -0.8

+273 0 -1 2516 ST(Tc) 5 3.39 x 10 x exp 0.0301( +273) ; 20 < 150 0 500 1000 1500 2000 2500

+273 Elapsed time per cycle (s)

ST was modified to reflect the effect of temperature change; STi

.Youngs modulus, E, was modified to reflect the effect of temperature change; Ei.

Proposed expanded WKR methodfor NI evaluation da

= C x dN 0.3 2.25 2.55 2.55 K() K()

1

=0 x x K () K () K () K () x i+1 i 12 i+1 0 i 0 ti+1 ti 12

Extended WKR Method to Non-Isothermal Condition (continued) 1.E+00 I1-1 Measured da/dN (mm/cycle)

I1-2 1.E-01 I1-3 I1-4 NI2-1 1.E-02 NI2-2 NI2-3 1.E-03 NI2-4 NI3-1 NI4-1 1.E-04 1.E-04 1.E-03 1.E-02 1.E-01 1.E+00 Extended WKR da/dN (mm/cycle) 13

Conclusions The comparison between the experimental fatigue lives and the predicted fatigue lives with the factor that considered the material variability showed that the experimental fatigue lives of non-isothermal condition were greater than the predicted fatigue lives.

The da/dN curves of the non-isothermal tests do not show great difference while those of the isothermal tests depended on the temperature and the strain history.

It is suggested that the effect of EAF on fatigue crack growth for non-isothermal condition is different from isothermal condition and/or the relation between microstructurally small crack (MSC) stage (Stage I) and crack growth stage (Stage II) for non-isothermal condition is different from isothermal condition.

The WKR method was modified to apply to non-isothermal condition by incorporating K and plastic correction. This extended WKR method was applied to the isothermal and non-isothermal tests and could estimate the test data with the factor of 2.

14

Backup Slides 15

Test Facility Fatigue test Flow section Flow Induction heater Specimen Induction Extensometer heater T/C GL : 24mm Heater output Input Water temp. Load output Electric power Disp.

Outer surface temp.

Strain output Fatigue test control unit Electric power Test control unit.

Loop control panel Time synchronization 16

Observation of Crack Surfaces NI2-1 NI3-1 NI4-1 Main Main Crack Sub Crack Crack Sub Crack Main Sub Crack Crack About About About 4mm 0.5mm 1.5mm Crack surface of NI2-1 has relatively large arc-like sub cracks The axial distance between the main crack and the sub crack of NI2-1 was larger than those of NI3-1 and NI4-1.

Main crack growth could be effected by interference by sub cracks 17

Proposal of a New Method Proposal to incorporate the effect of non-isothermal condition into UFen;

= x , x Correction factor for NI condition Stage I fatigue life under Stage II fatigue life under isothermal condition isothermal condition

, + ,

=

, + ,

Stage II fatigue life under Stage I fatigue life under NI condition NI condition If the crack growth is dominant, NI can be expressed by only crack growth life.

,

=

,

If the extended WKR method is improved and an appropriate initial crack is assumed, then Stage II fatigue life can be calculated and NI can be obtained.

18

TogetherShaping the Future of Electricity 19

ML18267A097: Difference between revisions

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1015 Ni EAF Testing
Person / Time
ML18267A097
Issue date:	09/24/2018
From:	Robert Tregoning NRC/RES/DE
To:
Shared Package
ML18267A083	List: ML18267A084 ML18267A085 ML18267A086 ML18267A087 ML18267A088 ML18267A089 ML18267A090 ML18267A091 ML18267A092 ML18267A093 ML18267A094 ML18267A095 ML18267A096 ML18267A097 ML18267A098 ML18267A099 ML18284A024
References
Download: ML18267A097 (19)
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