The influence of laser re-melting and alloying on the structure and properties of the X40CrMov5-l steel surface layer

This paper presents the results of laser re-melting and alloying parameters on the structure and properties of the surface layer of X40CrMoV5-1 hot work tool steels, using a high-power diode laser (HPDL). Investigation indicates the influence of the alloying carbides on the structure and properties of the surface layer of the steel, depending on the kind of alloying carbides and HPDL implemented. Laser alloying of the surface layer of the steel - without introducing alloying additions to the liquid molten metal pool and across the entire range of laser power used - causes a size reduction of the dendritic microstructure in the direction of crystallization, consistent with the direction the heat is being carried away from the laser beam's impact zone. Successful re-melting of the steel without introducing alloying additions into the liquid molten pool in the form of carbide powders causes a slight increase in the properties of the surface layer of the steel in comparison to analogical properties obtained through conventional heat treatment, depending on the laser beam power used for the re-melting. The increase in the hardness of the surface layer obtained throughout HPDL re-melting and alloying with carbides is accompanied by an increase in tribological properties, when compared to X40CrMoV5-1 steels processed with conventional heat treatment.