Study on micro – Melt polishing and strengthening mechanism of scanning electron beam surface

Abstract

Scanning electron beam micro-polishing is a new technique to reduce surface roughness using molten metal to fill pits under gravity's action spontaneously. In this study, through the establishment of the electron beam heat source model and heat conduction model, it is easy to obtain the mathematical and physical model of heat balance for continuous scanning electron beam process under micro-melting polishing and to discuss the influence of regularity of electron beam process parameters on the surface morphology and microstructure. The results showed that the surface roughness of 45 steel was reduced after scanning electron beam processing. The lowest value was 0.34 μm with a reduction of 83%. It was found that the melt zone was mostly martensite with fine grains by further measuring and analyzing the microstructure and hardness of the polished sample. The maximum hardness was 870 HV in the subsurface layer.