激光熔覆高强韧铁基合金涂层的组织及其轴承滚道服役性能

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

采用激光熔覆技术在42Cr Mo钢表面制备出厚度超过3 mm的含硼高强韧铁基合金涂层(S1涂层),研究了该涂层的显微组织及其轴承滚道服役性能,并与商用高硬度M2涂层进行了对比。结果表明:S1涂层与基体之间结合良好,组织由马氏体基体相和岛状共晶强化相M3C型碳化物组成;S1涂层的平均硬度约为883 HV,是M2涂层的1.1倍。在许用接触应力试验中,S1涂层表面的压痕深度均小于滚动元件直径的10^(-4),表现出稳定且优异的抗塑性变形能力;S1涂层轴承心部的理论最大剪切应力为377.38 MPa,低于M2涂层轴承心部(392.03 MPa),远低于轴承材料的剪切屈服应力(459 MPa),表现出较好的静载荷承载能力。S1涂层的滚动接触疲劳寿命为2.66×10^(7)周次,是M2涂层的2倍。

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 2.66×10^(7) cycles,which was one time higher than that of M2 coating.