Behaviour Characteristics of an In Situ Formed Laser Clad WC Particle Reinforced Composite Coating
J-H. LI and Y-X. Wang
Direct addition of a WC reinforced particle coating and in situ generation of a WC reinforced particle coating were prepared on the surface of H13 steel by adding a mixture of WC and (W+C) powder to Ni60 alloy powder using laser cladding with a fibre laser. The morphology of WC was predicted by MATERIALS STUDIO(8.0) and the formation mechanism of WC was explored. The phase composition and hardness of the two coatings were compared. The morphology diversity of WC particles in the coating was analysed. The predicted morphology of WC, the formation mechanism of WC and the morphology of the experimental coating were obtained. The results show that the formation of WC is predicted to be in the form of triangular prism, and the ratio of collision convection, temperature gradient and melting speed play a role in the growth of particles. The in situ formed WC reinforced phase coating has higher morphology quality, and there are many reinforced phases with uniform distribution. The microhardness of the coating is significantly higher than that of the coating directly added with WC reinforced particles. The shapes of WC particles are mainly petal-shaped, quadrate and triangular, and the main reasons for the difference from the prediction are collision convection, solid-liquid repulsion and inhibition of the formation of various generative phases.
Keywords: Fibre laser, H13 steel, WC, in situ generation, phase structure, formation mechanism, morphology