激光功率对Ni基WC熔覆层组织和性能的影响

Influence of laser power on microstructure and properties of Ni-based WC clad layer

采用半导体激光器,使用预置粉末的方式在Q235钢表面制备了Ni基WC复合涂层。使用扫描电镜、金相显微镜、显微硬度仪等分析了激光功率对熔覆层的宏观形貌、显微组织和性能的影响。结果表明：随着激光功率的提高,熔覆层的宽度、堆积高度和基底熔深均增大;熔覆过程中WC颗粒与Ni基合金之间发生了原子间的扩散,形成了冶金结合,生成了大量的富W、富Cr的碳化物硬质相,使涂层的硬度得到了很大的提高;随着功率的增大熔覆层的组织变的更加细小致密,形成大量的呈集群生长的树枝晶;熔覆层的显微硬度是基体的3～5倍。

Ni-based WC coating was prepared on the surface of Q235 steel by using semiconductor laser equipment and the method of preset powder. The phase composition ,morphology of the clad layers were investigated by metallurgical microscope, SEM and microhardness tester. The results show that with the increase of laser power, the width and the height of the clad layer and substrate melting depth increase. In the clad processing, atomic diffusion happened between the WC and the substrate materials, formed a metallurgical bonding and generated a large number of wealthy W, and Cr carbide hard phase, which made the hardness of the clad layer improved greatly. With the increase of laser power, the organization of cladding layer becomes more dense and form a large number of clustered growth dendrites. The average microhardness of the clad layer is 3-5 times as hard as that of the substrate.