Microstructure of High Strength and Toughness Fe-based Alloy Coating by Laser Cladding and Its Bearing Raceway Service Performance

A high strength and toughness Fe-based alloy coating (S1 coating) containing boron with a thickness of more than 3 mm was prepared on 42CrMo steel by laser cladding technology. The microstructure and its bearing raceway service performance of the coating were studied, and compared with those of the commercial high hardness M2 coating. The results show that the bonding between the S1 coating and the substrate was good, and the structure of S1 coating consisted of martensitic matrix phase and island eutectic strengthening phase M₃C type carbide. The average hardness of S1 coating was about 883 HV, which was 1.1 times that of M2 coating. In the allowable contact stress test, the indentation depth of S1 coating surface was less than 10^-4 that of the diameter of rolling element, showing stable and excellent anti-plastic deformation ability. The theoretical maximum shear stress of bearing core with S1 coating was 377.38 MPa, which was lower than that of bearing core with M2 coating (392.03 MPa) and much lower than shear yield stress of bearing material (459 MPa), showing better static load bearing capacity. The average rolling contact fatigue life of S1 coating was 2.66×10⁷ cycles, which was one time higher than that of M2 coating.