Evaluation of Irradiation Hardening of P92 Steel under Ar Ion Irradiation

P92 steel was irradiated with Ar ion up to 10 dpa at 200, 400, and 700 ◦C. The effect of Ar ion irradiation on hardness was investigated with nanoindentation tests and microstructure analyses. It was observed that irradiation-induced hardening occurred in the steel after Ar ion irradiation at all three temperatures to 10 dpa. The steel exhibited significant hardening at 200 and 700 ◦C, and slight hardening at 400 ◦C under Ar ion irradiation. Difference in the magnitude of irradiation-induced hardening at different temperature in the steel is attributed to different changes in the microstructure of the steel that arose from the irradiation. Irradiation-induced hardening in the P92 steel irradiated at 200 ◦C is attributed to the occurrence of both dislocation loops and other fine irradiation defects during irradiation. Slight hardening in the steel irradiated at 400 ◦C mainly arises from the annihilation of defect clusters at this temperature. The occurrence of fine Ar bubbles with high number density during the Ar ion irradiation at 700 ◦C resulted in the significant hardening in the steel.