Influence of Overlapping Ratio on Microstructure and Mechanical Properties of Hardened Layer

Abstract

The large area of electron beam transformation hardening is achieved by means of muti-channel scanning electron beam. Then the microstructure and properties of the hardening layer was discussed and analyzed. Scanning electron microscopy (SEM), EDAX energy dispersive spectroscopy (EDS) and other analytical testing methods are used to analyze the microstructure and phase composition of the hardened layer. Light-section microscope is used to measure the surface roughness. The result shows that the tempered microstructures of 45 steel are tempered martensite, tempered troostite and tempered sorbite after electron beam scanning. The hardness of the hardened layer is between 750 HV and 900HV which is about twice or three times as hard as the matrixs. The hardness of the tempered zones is between 424HV and 426HV which is a third of the matrixs; the surface roughness is nonlinearly declined with the increase of the overlapping ratio.