Microstructure modification and corrosion improvement of [formula omitted] steel induced by pseudospark electron beam treatment

Abstract

The pseudospark electron beam is a kind of pulsed electron beam characterized by fast and stable repetitive operations. It is able to achieve high rate of energy rise and plasma quenching. Thus, when used as an intense electron beam source for material processing, some unique properties are induced. The mechanism analysis of microstructure modification and corrosion improvement of AISI1045 steel treated by pseudospark electron beam are investigated. Results show that the amorphous phase is formed on the top surface of melted layer. The treated layer is several microns deep with nonuniform interface. Besides, material’s grain sizes are significantly reduced after pseudospark treatment. The average grain size in the heat affected zone is smaller than that in the melted zone, which is attribute to the combination effect of temperature-induced dynamic thermal stress fields and the highest temperature gradient. Furthermore, electrochemical impedance spectroscopy (EIS) and potential polarization analysis are used to study the corrosion behavior of samples pre and post pseudospark electron beam treatment. The improvement of corrosion resistance is due to the combination effects of the formation of austenite, the removement of impurities during the electron beam surface treatment process and the formation of the amorphous phase acted as a homogeneous passive film.