ステンレス鋼の引張りおよびクリープ特性に及ぼす中性子照射効果

概要

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In order to investigate the effects of neutron irradiation on the creep and tensile properties of stainless steels, post-irradiation tests were made on the specimens of FBR grade type 316 stainless steel(316FR)and type 304 stainless steel. The post-irradiation tensile tests showed that the fracture elongation of both 316FR and type 304 stainless steel decreased and the 0.2% proof strength incresed by irradiation. These phenomena are related to the point defect accumulation due to neutron irradiation. The post-irradiation creep test of 316FR demonstrated that the time to rupture decreased to between 1/3 and 1/5 of the unirradiated one, and this reduction is smaller than that of type 304 stainless steels under the same irradiation and test conditions. The creep property degradation of type 304 stainless steel due to the irradiation is caused by accumulation of helium bubbles at the grain boundaries. As for 316FR, it is considered that beyond the neutron exposure level of 0.3dpa a growth of phosphide caused a decrease in solution hardening and accumulation of helium bubbles at the grain boundaries. It is concluded that the reduction ratio of time to rupture for both 316FR and type 304 stainless steels after irradiation became larger than 1/30, which is the lower limit of the reduction ratio for the "Monju" FBR.
社団法人日本材料学会の論文
1997-05-15