Study on effect of microstructure on crack propagation behavior in austenitic stainless steels

Kaji, Yoshiyuki  ; Kondo, Keietsu  

In order to investigate the influence of neutron dose rate on crack propagation behavior of type 304 stainless steel, crystallographic analyses around the cracks were conducted by Electron Backscattered Diffraction (EBSD) on crack growth rate (CGR) tested specimens irradiated at the Japan Materials Testing Reactor (JMTR) up to about 1dpa under the dose rate conditions from 1E-8 to 1E-7 dpa/s. Although CGRs of specimens with different dose rates suggested that specimens with the higher dose rate irradiation showed the slightly larger CGR than that with lower dose rate irradiation, estimation of the plastic strain by means of the EBSD measurement revealed that plastic strain around the crack in both low and high dose rate specimens was estimated to approximately 1%, and the significant difference was not observed. Furthermore, the distribution of plastic deformation around the crack is estimated on the specimens irradiated up to about 2 dpa and the influence of neutron dose rate on crack propagation behavior is discussed in this study.