Residual stress distribution and wear behavior in multi-pass laser cladded Fe-based coating reinforced by M3(C, B)

A novel high hardness Fe-based composite coating reinforced by M3(C, B) carboboride was prepared by laser cladding. The microstructure and solidification process of the coatings were characterized. The residual stress distribution of the coating was studied. The wear resistance of the coating was tested, and the wear mechanism of the coating was analyzed in detail. The results showed that the microstructure of the coating was martensite with nano-twin, M3(C, B) carboboride precipitated along the grain boundary, and block carbide located therein the matrix. Due to the synergistic effect of thermal stress and phase transformation stress, the residual stress distribution of the coating was compressive stress, and the interface between the coating and substrate was low residual tensile stress, which was beneficial for reducing the risk of cracking from the coating. The average hardness of the coating was over 850 HV, which was 2.5 times than that of the 42CrMo substrate (335 HV), and the wear resistance of the coating was 0.92 × 10−5 mm3/N·m, which was 98.3% lower than that of the 42CrMo substrate (54.7 × 10−5 mm3/N·m), indicating the very high hardness and excellent wear resistance of the coating.