Characterization of proton-irradiated Chinese A508-3-type reactor pressure vessel steel by slow positron beam, TEM, and nanoindentation

Evolution of matrix defects and hardening of Chinese A508-3-type reactor pressure vessel steel irradiated to the doses of 0.05 dpa, 0.1 dpa, and 0.2 dpa by 110-keV proton at room temperature were investigated by slow positron beam, TEM, and nanoindentation. Slow positron beam results showed that proton irradiation-induced vacancy-type defects were observed and only one type of vacancy-type defects was characterized. Size and concentration of vacancy-type defects increased with the dose. TEM images revealed that dislocation loops were produced in the proton-irradiated samples. The mean size of the dislocation loops was unchanged but the number density of the dislocation loops was increased with the dose. An obvious hardening phenomenon of proton irradiated samples was detected by nanoindentation test. The irradiation hardening was mainly attributed to irradiation-induced matrix defects such as vacancy clusters, H-vacancy complexes, and dislocation loops.