Microstructural study of the surface layers irradiated by high-energy electron beam in a plain carbon steel

Abstract

An investigation was conducted into the microstructural analyses of the surface layer hardened by the irradiation of high-energy electron bean in a 0.38% C plain carbon steel. Steel specimens were irradiated using an 1.4 MeV electron accelerator, and the microstructures of the irradiated surface layers were examined. The ferrite-pearlite structure near the specimen surface was changed to the dual-phase structure, i.e., ferrite and Inartensite upon irradiation. In order to investigate this martensitic transformation mechanism, the simulation test including thermal cycles of abrupt heating and quenching was carried out. The results indicated that the temperature of tile irradiated surface layer was raised to about 1100 degrees C and then quenched to room temperature, which was enough to obtain the surface hardening through the transformation to martensite. The surface irradiation effect on hardness was also analyzed by the irradiation condition such as beam moving speed and heat input.