42CrMo钢表面激光熔覆颗粒增强Co基涂层的组织与性能

为改进矿用截齿的耐磨性能，使用激光熔覆技术在截齿用42CrMo钢基体表面制备Co基复合涂层，并分析涂层的微观组织、硬度和耐磨性。结果表明，熔覆层形貌良好且与基体呈冶金结合。在激光作用下，WC颗粒发生溶解并与多种元素发生反应，熔覆层主要由γ-(Co, Fe)和碳化物组成。熔覆层组织呈梯度变化，过渡区组织为平面晶、枝状晶和柱状晶，熔覆区组织则为等轴枝晶和均匀分布的富W、Ti的碳化物颗粒。熔覆层平均显微硬度为995 HV,远高于基体(328 HV),同时热影响区的硬度也大幅提高。在相同的磨损条件下，熔覆层摩擦因数较低，体积磨损量仅为基体的13.5%。在摩擦过程中，弥散分布的细小碳化物颗粒逐渐凸起并起到承担载荷和抵抗磨损的作用，使熔覆层具有良好的耐磨性，磨损机制为轻微磨粒磨损。激光熔覆技术制备的颗粒增强Co基涂层，组织致密，性能良好，能显著地提高42CrMo钢的表面硬度和耐磨性。

Microstructure and properties of particles reinforced Co-based coating by laser cladding on 42CrMo steel

Co-based composite coating was prepared on surface of 42CrMo steel by laser technology to improve the wear resistance of mining pick, and the microstructure, hardness and wear resistance of the coating were analyzed. The results show that the clad layer has good morphology and metallurgical bonding with the substrate. Under the action of laser, WC particles dissolve and react with various elements. The clad layer is mainly composed of γ-(Co, Fe) and carbides. The microstructure of the clad layer is gradient, and the clad zone consists of equiaxed dendrites and carbide particles rich in W and Ti, while the transition zone consists of planar, dendritic and columnar grains. The average microhardness of the clad layer is 995 HV, which is much higher than that of the substrate (328 HV), and the hardness of the heat affected zone is also greatly increased. Under the same wear conditions, the friction coefficient of the clad layer is low, and the volume wear amount is only 13.5% of the substrate. In the process of friction, the dispersed fine carbide particles gradually protrude and play the role of bearing load and resisting wear, so that the clad layer has good wear resistance, and the wear mechanism is slight abrasive wear. The particle reinforced Co-based coating prepared by laser cladding technology has dense structure and excellent performance, which can significantly improve the surface hardness and wear resistance of the 42CrMo steel.