Anisotropy in Microstructure and Wear Performance of CoCrMo Alloy Melted by Laser Selective Melting

In this study, CoCrMo alloys were successfully prepared by laser selective melting, and the CoCrMo alloy specimens were tested in two planes, transverse and longitudinal, respectively. The microstructures were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and electron backscattering diffraction (EBSD).The results show that the longitudinal plane shows typical fish scale morphology, the average diameter of the grains is 44.2 μm, showing a weak <100> and <111> weave; while the transverse plane mainly consists of fine hexagonal cellular structure, grain orientation preferentially grows along the <110> direction, the average diameter of the grains is 29.5μm, which is 33.26% lower compared with that of the longitudinal plane; the small angle grain boundaries, hardness and friction coefficient of the transverse plane molding samples The small-angle grain boundaries, hardness and friction coefficient of the transverse plane molding specimens were 39.6%, 435 HV and 0.5958, respectively, while those of the longitudinal plane were 28.6%, 416 HV and 0.7529, respectively.SLM-formed CoCrMo alloys have obvious anisotropy in both microstructure and mechanical properties. The high hardness of transverse plane-formed specimens is attributed to the fine-grained reinforcement and higher initial dislocation density; and the excellent wear properties are mainly attributed to their cytosolic microstructures, which are easy to adhere to the wear tracks and improve the wear resistance. This study reveals the mechanism of anisotropy of microstructure and mechanical properties of CoCrMo alloy melted by laser selective melting, which provides a theoretical basis for the application of CoCrMo alloy in production.