Ni基合金与WC混合粉末的激光熔覆层组织

为了提高矿山机械零部件的耐磨性能及使用性能,采用激光熔覆方法在45#钢基体上制备了Ni基合金与WC混合粉末的复合涂层,研究了熔覆层的物相组成、WC颗粒在Ni基合金涂层中的分布,以及加入50%WC颗粒后Ni基合金涂层的裂纹敏感性、显微组织、成分及硬度。结果表明,合理的工艺参数使WC颗粒分布均匀,与基体结合牢固,并保持原始的形状;熔覆层内没有裂纹产生;熔覆层与基体之间形成了冶金结合;熔合线附近由亚共晶组织(初晶的富Ni奥氏体γ-Ni与共晶组织)构成;熔覆层中上部由过共晶组织(初晶的碳化钨与共晶组织)构成,初晶碳化钨的形态有珊瑚状、等轴晶状、柱状及交互结晶状等;激光熔覆层硬度是45#钢基体的5倍以上。

Microstructure of Laser Cladding Layer Prepared by Mixed Powder of Ni-based Alloys and WC

In order to improve the wear resistance and using performance of the parts of mining machinery, the composite coatings of Ni-based alloys and WC mixed powder were prepared on 45# steal by laser cladding. The phase composition of the cladding layer and the distribution of WC particles in the coating of the Ni-based alloys, as well as the crack sensitivity, microstructure, component and hardness of the Ni-based alloys coating prepared with 50% WC particles, were researched. The results show that appropriate technological parameters make WC particles distribute uniformly, combine strongly with the Ni-based alloy and maintain the original shape. There is no crack in the cladding layer. Also the cladding layer has a metallurgical bonding with the substrate. The microstructure near fusion line is hypoeutectic structure （Ni-rich austenitic T-Ni which crystallized first and eutectic） ; the microstructure in the upper part of cladding layer is hypereutectic structure （tungsten carbide which crystallized first and eutectic）, the shapes of tungsten carbide which crystallized first are coralline, equiaxed grains, columnar, interaction, etc. The Vickcrs hardness of the cladding layer is more than five times compared with that of the substrates.