Effect of laser parameters on microstructure and properties of H13 steel surface quenched layer

In order to investigate the effects of different combinations of laser process parameters on the laser quenching modified layer of H13 steel, seven groups of control experiments were set up to analyze the cross-section macroscopic morphology, physical phase composition, microstructure, microhardness, and friction wear properties of the modified layer. And the difference of microstructure and properties between overburn melting and quenching was specifically compared. The results show that increasing the laser power or decreasing the scanning speed can effectively improve the depth and width of the quenching zone. However, when the parameter combination reaches a certain limit, the phenomenon of overburning melting will occur, which will affect the surface flatness of the workpiece. With the increase of laser power or the decrease of scanning speed, the microstructure of the modified layer changes from incomplete phase transformation to complete phase transformation. When reaching a certain limit, some of the carbides precipitated are nodular in character. Overburning melting results in as-cast dendrite structure. The hardness of the cross section shows an increasing trend with the increase of laser power or the decrease of scanning speed, and the highest hardness appears in the subsurface region. The as-cast dendritic structure significantly increases the hardness compared to the quenched structure. With the increase of wear time, the increasing range of wear weight loss of laser quenched samples decreases, and the wear modes are mainly abrasive wear and adhesive wear.