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Title:
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Fracture toughness of neutron irradiated solid and powder HIP 316L(N): ITER Task T214, NET deliverable GB6 ECN-5
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Author(s):
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Published by:
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Publication date:
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ECN
NUCLEAIR
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1998
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ECN report number:
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Document type:
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ECN-C--98-033
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ECN publication
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Number of pages:
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Full text:
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35
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Download PDF
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Abstract:
The fracture toughness properties of unirradiated and neutron irradiatedtype 316L(N) stainless steel plate (European Reference Heat ERHII),
conventional 316L(N) solid HIP joints (heat PM-130), and 316L(N)-1G powder
HIP material have been measured. Compact tension specimens with a thickness
of 12 and 5 mm were irradiated in the High Flux Reactor (HFR) in Petten, The
Netherlands, simulating the fusion reactor's first wall conditions by a
combination of high displacement damage with proportional amounts of helium.
The solid HIP (or HIP-bonded) CT-specimens were irradiated in two separate
experiments: SIWAS-6 with 1.3 to 2.3 dpa (1.7 dpa av.) at 353 K, and
CHARIOT-3 with 2.7 to 3.1 dpa (2.9 dpa av.) at 600 K. The plate material and
powder HIP CT-specimens were irradiated in one experiment only, SIWAS-6. The
helium content is up to 20 appm for the 2.9 dpa (av.) dose level. Testing
temperatures of 353K and 573K have been used for the fracture toughness
experiments. The report contains the experimental conditions and summarises
the results, which are given in terms of J-resistance curve fits. The main
conclusions are that all three materials have very high toughness in the
unirradiated state with little difference between them; the solid HIP has the
highest toughness, the powder HIP lowest. The toughness of all three
materials is reduced significantly by irradiation, the reduction is the least
for the plate material and the highest for the powder HIP material. However,
many, but not all, of the solid HIP CT specimens showed debonding of the
joint during testing. The machined notch of the CT specimens was not exactly
on the joint interface, which could lead to unjustified interpretation of the
measured values as being the toughness of the joint, the toughness of the
joint being probably much lower. The reduction by irradiation of the fracture
toughness of the powder HIP material is clearly larger than for plate
material, which is confirmed by the observed early initiation of stable crack
extension. As these fracture toughness measurements have been obtained by
using CT specimens with a thickness of 12 and 5 mm, and as unirradiated
austenitic stainless steel has a very high toughness, the values presented do
in general not qualify as a size independent material property, but can be
used as valid data for constructions with thicknesses of respectively 12 and
5 mm. 12 refs.
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