Scanning electron beam surface strengthening of column-faced 45 steel

Abstract

• Columnar surface strengthening by scanning electron beam technology. • The effect of curvature on the microstructure of the fusion zone is investigated. • The relationship between microhardness distribution and curvature is established. • The carbon content of the sub-surface is higher than that of the near surface. To conquer the shortcomings that the column-faced 45 steel is susceptible to wear and failure, scanning electron beam was conducted to strengthen it, the microstructure and microhardness of the modified layer under variable workpiece curvature were investigated. The results revealed that the modified layer was composed of fusion zone and heat-affected zone, the depth of the modified layer manifested an ascend tendency as the increment of curvature. Martensite dominates the modified layer, and the carbon content of martensite for the sub-surface is higher than that of the near surface, moreover, the grain size of martensite first reduced and then increased with increasing of curvature. The position of the maximum microhardness along the direction of depth as the curvature increases, and the maximum microhardness of 1/20 curvature is 688.26 HV, which is about 3.13 times that of the matrix. This study demonstrated the potential of using scanning electron beam to reinforce column-faced 45 steel.