Enhanced corrosion and wear properties of H13 steel with Co‐based alloy coating prepared by laser cladding

Abstract

In this study, Stellite 21 Co‐based alloy coating was prepared on the surface of the H13 steel substrate by laser cladding. The phase composition, microstructure, chemical constitution, microhardness, and wear property of the coating were studied, respectively. The corrosion resistance of the coating was evaluated by electrochemical test and salt spray test. The results show that the coating is mainly composed of γ‐Co, CoCx, and Cr7C3 phases. γ‐Co solid solution matrix separates within the dendrites, while Mo‐rich intermetallic phases and carbides separate in the interdendritic regions. The average microhardness of the coating is twice that of the H13 substrate. The wear loss of the coating is 74.3% lower than that of the substrate, exhibiting better wear resistance. The main strengthening mechanisms of the coating are solid solution strengthening and second phase strengthening. The self‐corrosion potential of the coating is more positive than that of the H13 steel and the corrosion current density is only 1/160 of the H13 steel. The salt spray test after 168 h reveals that the coating exhibits much better corrosion resistance than that of the substrate.