ECN publication
Irradiation testing of stainless steel plate material and weldments: report on ITER task T14, part A: low cycle fatigue properties after 0.5 and 5 dpa at 350 K
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ECN report number: Document type:
ECN-C--97-087 ECN publication
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The low cycle fatigue properties of unirradiated and neutron irradiatedType 316LN-SPH stainless steel plate and EB welded material have been measured at a temperature of 350K. Miniaturized test specimens of the European reference heat 1 for fusion (ERH1) have been irradiated in the High Flux Reactor (HFR) of Petten, Netherlands, simulating the first wall conditions by a combination of high displacement damage with high amounts of helium. This work was performed as part of the European Fusion Technology Programme for ITER as 'Irradiation testing of stainless steel'. The report contains the experimental conditions and summarizes the test results. The stress strain response of EB welded material was found to be identical to that of plate material. For both plate and weldments a large increase in first cycle tensile stress is observed, which saturates within 0.7 dpa. The irradiated material shows continuous cyclic softening during low cycle fatigue testing, decreasing to about the stress level of unirradiated material at fatigue life. EB welded material tends to have longer mean fatigue lives than plate material, but the data have overlapping scatter bands. Material irradiated to 0.7 dpa and material irradiated to 5 dpa show similar fatigue life behaviour as unirradiated material. It is demonstrated that the RCC-MR curve is sufficiently conservative for use as design curve in case of application of Type 316LN-SPH plate and EB- welded material at the temperature of 350K. Furthermore, it is also demonstrated that for irradiation damage dose levels up to 5 dpa at 350K there is no need to apply additional safety factors for the number of allowable cycles up to 105 cycles. 15 figs., 6 tabs., 18 refs.

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