Analysis of crack behavior for Ni-based WC composite coatings by laser cladding and crack-free realization

The crack behavior of Ni-based WC composite coatings by laser cladding was investigated. The results showed that cracks originated from the interface of the composite coating and the substrate, and then passed through the precipitated carbides due to the dissolution of WC particles. To increase the efficiency of laser cladding and eliminate the well-known crack problems in the composite coatings, laser induction hybrid rapid cladding (LIHRC) was carried out experiments to produce Ni-based WC composite coatings on A3 mild steel. The laser scanning speed and the powder flow rate increased with the increasing of the preheated average temperature of the substrate during LIHRC. The dissolution of WC particles decreased due to high laser scanning speed, contributing to reduce the porosities in the composite coatings. Moreover, the temperature gradient decreased with the increasing of the preheated average temperature of the substrate during LIHRC, which was the main reason why Ni-based WC composite coatings were free of cracks. (C) 2008 Elsevier B. V. All rights reserved.