Effect of Ni on the microstructure and properties of laser cladding 316 L+410 composite stainless steel coatings

Laser direct deposition is commonly used in repair and remanufacturing due to its advantages of small heataffected zone, compact structures, and rapid cooling. In this study, stainless steel coatings with different Ni contents were applied on the surface of 24CrNiMo using laser direct deposition. The structure and properties of the cladding layer were analyzed using XRD, SEM, microhardness tester, universal testing machine and ball-disk wear tester. The results revealed that an increase in Ni content led to a transition in the microstructure of the cladding layer from martensitic to austenitic. According to the Creq/Nieq ratio, the coating solidifies in different modes. At a Ni content of 2 %, a region with equiaxed crystals and martensitic structure was observed. Moreover, the hardness of the cladding layer decreased from 446 HV0.2 to 200 HV0.2 with higher Ni content. The wear of the cladding layers increases with the increase of Ni element. However, the oxidative wear of the cladding layers can be improved with the addition of Ni. Interestingly, at a Ni content of 2 %, a new martensite + austenite duplex the structure of stainless steel was identified in the cladding layer, which effectively enhanced its tensile strength and plasticity. In addition, with the addition of Ni elements can effectively improve the plasticity of the coating.