Copyright © 2016 SCK•CEN Effects of Irradiation on the Tensile and Fracture Properties of 316L Stainless Steel R. Chaouadi, E. Stergar and S. Gavrilov SCK•CEN, Boeretang 200, 2400 Mol, Belgium [email protected] 1 International Light Water Reactors Material Reliability Conference Chicago, 1–4 August 2016
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Copyright © 2016
SCK•CEN
Effects of Irradiation on the Tensile and Fracture
Properties of 316L Stainless Steel
R. Chaouadi, E. Stergar and S. Gavrilov
SCK•CEN, Boeretang 200, 2400 Mol, Belgium
1
International Light Water Reactors Material Reliability Conference
Chicago, 1–4 August 2016
Copyright © 2016
SCK•CEN
Objectives and Motivation
316L Irradiation hardening saturation at high dpa (roughly
above 5 dpa)
Most significant effects observed at low fluence levels,
typically between 0 and 1 dpa
Focus on the 0 – 1 dpa region
Tensile properties evolution
Crack resistance behavior
Correlation between tensile properties and crack resistance
2
Copyright © 2016
SCK•CEN
Irradiation Hardening of 316L
3
More significant effects observed in the low dpa range
In particular 0 – 1 dpa RADAMO-12ext Irradiation Program
DATA from
Robertson et al., ASTM
STP 1325 (1999) 671 –
688.
ITER MPH (Material
Properties Handbook)
Elen et al., JNM 191-194
(1992) 766–770.
Maloy et al., OECD/NEA
(2002) 669–680.
Copyright © 2016
SCK•CEN
Irradiation ProgramRADAMO–12ext
Irradiation
43=12 tensile specimens: L=24 mm , 2.4 mm (A)
3 microstructural bars: 32 mm long , 8.5 mm (A)
6 PCCv (PreCracked Charpy specimens) (E)
dosimeters : (A) and (E)4
PCCv specimens
tensile specimensmicrostructural bar
Copyright © 2016
SCK•CEN
Dosimetry and Test Matrix
5
Tensile specimens corresponding to
5 different dpa levels : 0.15 – 0.83 dpa
PCCv specimens corresponding to 5
different dpa levels : 0.18 – 0.79 dpa
3 tensile specimens/position
Tensile tests at 25°C and 290°C
Crack resistance tests at 25°C and 290°C
Copyright © 2016
SCK•CEN
Tensile Test Results
6
Copyright © 2016
SCK•CEN
Significant effect on the tensile curve
7
Tensile Test Results
yield strength
From the 3 available
specimens
One test at 25°C
One test at 290°C
One spare specimen
Copyright © 2016
SCK•CEN8
Tensile Test Results
Copyright © 2016
SCK•CEN
Tensile Test ResultsStrength
Significant yield strength increase in the 0–1 dpa range
9
Copyright © 2016
SCK•CEN
Tensile Test ResultsStrength
10
Significant Yield strength increase in the 0–1 dpa range (damage rate)
onset of plastic flow localization
Copyright © 2016
SCK•CEN
Superposition of the irradiated flow curves on the unirradiated one by shifting
in the true strain direction (sy irrad (0.2%)= sy unirrad (0.2%+Deoffset)
Irradiation effect similar to strain hardening
11
Tensile Test Results @ 25°C
yield strength (sy)
Deoffset
Deoffset
Copyright © 2016
SCK•CEN
Crack Resistance Characterization
12
Copyright © 2016
SCK•CEN
Crack Resistance Test Results
13
Four different techniques are used
Unloading compliance (UC)
Potential drop (PD)
Normalization data reduction (NDR)
Energy normalization
Test temperatures
25°C
290°C
ASTM E1820
used at SCK•CEN
Copyright © 2016
SCK•CEN14
Tensile Test Results
Strictly speaking, test results are not valid according to E1820 size
requirement (inadequate specimen size)
Not so critical as we under-estimate actual resistance curve
Copyright © 2016
SCK•CEN
Crack Resistance Test Results
15
Based on energy
normalization
technique
Copyright © 2016
SCK•CEN
Crack Resistance Test Results
16
No significant effect on
initiation toughness (JQ and
J0.2 mm) and tearing resistance (TM)
J0.2 mm
JQ
TM
Copyright © 2016
SCK•CEN17
SEM Examination of the Fracture Surfaces
No significant effect of irradiation on dimple size suggesting a constant critical
void growth rate
TSW4-19 (0.18 dpa) TSW4-18 (0.68 dpa) TSW4-17 (0.79 dpa) DCT6-3-2-13 (2.5 dpa)
Copyright © 2016
SCK•CEN
Conclusions
The damage rate increases significantly in the low neutron dose
range (<1 dpa)
Despite the significant changes of the tensile properties
(strength and ductility) in the low dpa range, fracture behavior
remains almost unaffected
Fracture surface examination by SEM show very similar dimple
structure
Ductility loss is compensated by strength increase allowing an
unvariable critical void growth rate
18
Copyright © 2016
SCK•CEN
Closing Remarks
Additional tests on specimens irradiated at 300°C to 2.5 dpa (in
progress)
Microstructural examination
Crack resistance tests on specimens irradiated to 5 – 30 dpa
(LEXUR-II) longer term
19
Related Documents
