Effect of Powder Temperature per Unit Mass on in situ Laser Clad WC-enhanced Ni-based Coatings
Y-X. Wang, J-H. Li, F-P. Yao, H-H. Guo and X-X. Li
WC-enhanced Ni-based coatings were prepared in situ on a H13 steel substrate by laser cladding with a fibre laser. The influence law of the central temperature per unit mass of powder, η, acting on the morphology, microstructure, microhardness and friction wear properties of the coating was investigated. The results show that the metallurgical bonding between the WC–enhanced Ni-based coating and base metal (BM) was good. The dilution rate of the clad layer increases with the increase of η. WC, Cr3C2 reinforcing phases, FeNi3 solid solution, FeC carburized body, Fe3W3C interstitial compound are mainly present in the coating at different values of η. The microstructure gradually changes from dendritic and cellular to irregular aggregation with increasing η. The microhardness of the coating increases first and then decreases with the increase of η. The microhardness of the coating is the highest when η=16483 K/g. A value of η=16483 K/g gave the best wear performance. The wear mechanism of the WC-enhanced Ni-based coating is mainly adhesive wear, brittle spalling and abrasive wear.
Keywords: Fibre laser, H13 steel, WC-enhanced Ni-based coating, laser cladding, central temperature, in situ generation, microstructure, microhardness, wear mechanism