Effect of multiple laser re-melting on microstructure and properties of Fe-based coating

The aim of this article is to explore the effect of re-melting times on the microstructure and properties of Fe-based coating. In this study, the Fe-based coating is prepared on 316L stainless steel by laser cladding and laser re-melting. Meanwhile, the microstructure and properties of the coating are studied by 3D laser scanner, Vickers microhardness tester, X-ray diffractometer, and scanning electron microscope. In addition, the effect of laser re-melting times on microstructure formation that is analyzed by numerical simulation. The results show that re-melting can lead to the decrease in coating height, increase in coating width, and increase in both depth and width of melting pool. The hardness of coatings is enhanced by six times compared with the substrate. However, it was found that the hardness of the coating decreased with the increase in laser re-melting times. The abnormal decrease in hardness was analyzed because of the continued growth of crystals in the coating and an increase in the coating dilution rate. The first laser re-melting results in the obvious change of coating crystal. The crystals of the multiple laser re-melting coating continue to grow. Our research results can provide reference for laser multiple re-melting in industry.