Effect of laser scanning velocity on the microstructural changes and mechanical properties of the H13 steel part treated by laser surface remelting

Abstract

Abstract This paper investigates the effect of laser scanning velocity on the structural changes and mechanical properties of a H13 steel part treated by laser surface remelting. A high energy density laser with a large laser beam was used to improve the processing efficiency. The room temperature phases are dominated by martensite, retained austenite, and carbides. The laser treatment effects under various exposition conditions are compared in terms of heat affected depth, surface topography, and mechanical properties. The strengthening mechanisms include grain refinement, dislocation and precipitation strengthening, which act simultaneously during the laser remelting process to confer a high hardness at the surface of the H13 steel workpiece. Due to its higher yield strength and lower elongation, failure in the remelting zone occurred at the grain boundaries of the dendrites and in between the heat affected zone (HAZ) and the parent metal (Base Metal). These results can support the mass production of surface hardened H13 steel moulds using a laser treatment (high laser density and large laser heat source) with apprehensible changes of properties.