Microstructure characteristics of Ni-based WC composite coatings by laser induction hybrid rapid cladding

Abstract

To avoid low cladding rate and cracks of cladding layer, laser induction hybrid rapid cladding (LIHRC) has been put forward in the paper. The microstructure characteristics of Ni-based WC composite coatings at the different laser scanning speed were investigated. For low laser scanning speed, the growth of γ-nickel was characterized by coarse columnar dendrites and eutectics, blocky W 2C + Fe 3W 3C carbides, and bar-like (W, Cr, Ni) 23C 6 carbides were formed. With increasing laser scanning speed, the growth of γ-nickel presented the fine dendrites and eutectics, the only blocky mixed carbides were precipitated and identified as W 2C + FeW 3C + W 6C 2.54 carbides. With further increasing laser scanning speed, the growth of γ-nickel was characterized by cellular crystals and eutectics, the only blocky carbides were identified as W 2C + W 6C 2.54. Moreover, experimental results showed that the efficiency of LIHRC was increased much four times higher than that of laser cladding without preheating, ceramic–metal composite coatings detected were free of cracks and had a good metallurgical bonding with substrate.