Application of Fiber Laser for Surface Alloying of 95Cr18 Steel

The influence of the modes and conditions of laser surface alloying of the corrosion-resistant 95Cr18 steel (440C, 440B—analogues in the United States) was investigated. The structure, quality, and geometric parameters of the surface layers created as a result of laser exposure were studied. Powders of chemical compounds, such as B4C, WC, TiB2, W2B5, TiSi2, and HfSi2, were used for alloying; processing in an argon medium was carried out using a fiber laser with a wavelength of 1.06 microns. During the experiments, optimal parameters, such as the beam focusing size, scanning speed, and radiation output power, were selected. With increasing power, the volume of the melt bath increased as did both the depth and width of the alloying zone. Thus, with a laser power of 2 kW, the width of the doping zone reached ~3 mm. The depth of the alloyed layers on the surface of that steel was 400–700 microns in the power range of 1–2 kW. The microhardness of the alloy zones of 95Cr18 steel could be at the level of 4500–12 000 MPa. At the same time, with a decrease in the depth of the alloyed layer, the microhardness may increase due to an increase in the concentration of alloying components. For boron carbide in the solid phase quenching zone, the maximum increase in the microhardness of the surface layer reached 14 000 MPa.