Effect of laser cladding modes on plastic deformation inhomogeneity of surface hardened stainless steel

This work aims to study plastic deformation inhomogeneity of laser-cladded flat samples under uniaxial tensile. High-nitrogen Cr-Mn-Ni austenitic stainless steel was chosen as the substrate material. Laser cladding was implemented by applying Ni-Cr-Fe + WC powder at varying laser power (1-2 kW) and scanning speed (0.008-0.035 m/s). The penetration depth of a single roller decreased with the increase in scanning speed. The microhardness exhibited wide ranging with the cladding thickness (from 700 to 1350 HV) and decreased with increasing scanning rate. The mechanical test data showed that the surface hardening of austenitic steel led to an increase in the tensile strength and a decrease in ductility. The effect of laser cladding modes on the degree of plastic flow inhomogeneity within the micro-volumes of the cladded layer and the surface was established using digital speckle photography. The local strain variation in the sample increased with an increase in the specific energy of laser cladding. The structural heterogeneity near the interface between the cladded layer and the substrate exerts an impact on the development regularity of localized plastic flow. Unfavorable choice of laser parameters leads to formation of micro-cracks and porosities in the microstructure.