Effect of laser power on microstructure and properties of high-speed laser cladding of S890 steel

High-speed laser cladding was utilized to deposit a stainless steel coating on an S890 high-strength steel shaft and a laser power range of 2400 to 4200 W. The microstructure, mechanical properties, and grain growth behavior of the coating were systematically investigated. As the laser power increases, coating thickness, the width of the heat-affected zone, and the dilution rate exhibit a gradual upward trend, whereas the surface roughness initially decreases and subsequently increases, the grain size initially decreases and subsequently increases, and the element distribution becomes progressively more non-uniform. The microstructure of the coating predominantly consists of fine equiaxed grains and columnar grains, with the major phase being α-Fe. Compared to the substrate, the coating demonstrates enhanced hardness and corrosion resistance, the maximum hardness of the coating increases by 131.3%, and the corrosion tendency of the optimal coating decreased by 81.8%. Crystal grain refinement, homogeneous distribution of elements, and a high content of high-angle grain boundaries contribute to impeding dislocation movement, thereby prominently enhancing the mechanical properties of the coating. The high-speed laser cladding technology not only facilitates the improvement of the coating’s forming quality but also reinforces its surface strength and comprehensive performance.