2010 Fiscal Year Final Research Report

Recovery of mechanical property in low-activation vanadium alloys in post-irradiation heat treatment

Research Project

Project/Area Number	20560763
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Nuclear fusion studies
Research Institution	University of Fukui
Principal Investigator	FUKUMOTO Kenichi University of Fukui, 附属国際原子力工学研究所, 教授 (30261506)
Project Period (FY)	2008 – 2010
Keywords	低放射化バナジウム合金 / 照射脆性 / 熱回復 / 補修技術
Research Abstract	In order to improve the irradiation embrittlement of low activation-induced V-4Cr-4Ti alloy after neutron irradiation below 300C, a research for post-irradiation heat treatment for neutron-irradiated vanadium alloys was conducted. It was found that an anneal treatment at 500C for 10 to 20 hours in a vacuum was required tomake the ductility of irradiated vanadium alloys recovered in tensile test after the anneal treatment. The recovery of ductile behavior in irradiated vanadium alloys is caused by the transition of deformation mode from rapid local necking deformation to uniform deformation due to the reduction of barrier strength factor for defect clusters. It was considered that the reduction of barrier strength factor for defect clusters against dislocation motion during deformation was brought by desorption of interstitial gas impurities from defect clusters after anneal treatment as the interstitial impurities had been absorbed in dislocation core in the as-irradiated ones.