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采用CO2激光在45钢表面制备镍基纳米WC/Co复合熔覆层,在激光单道熔覆的基础上进行激光搭接熔覆。通过SEM、XRD、EDS以及显微硬度测试,分别对激光单道及搭接熔覆层的显微组织、物相、成分及硬度进行比较研究。结果表明:选择合适的激光熔覆工艺,可以在45钢表面获得基本上消除了裂纹和孔洞,并与基体呈冶金结合的镍基纳米WC/Co复合熔覆层及其搭接熔覆层。熔覆层的物相为γ(Fe-Ni)基体上分布着以WC、W2C为主的碳化物相。其中激光单道、搭接熔覆层显微硬度分别为779.3~1315.0HV0.1、600.3~1560.0HV0.1。尽管单道及搭接熔覆层中碳化物的种类不变,但其形态和分布有较明显差异,搭接熔覆层较单道熔覆层中碳化物形态多样性及分布不均匀性更大一些。无论激光单道或搭接熔覆层中,都存在含相当数量的粒度≤100nm的纳米颗粒,分析认为这些纳米颗粒最有可能为WC、W2C为主的碳化物,对于熔覆层的抗裂止裂起了关键的纳米效应作用。本文研究的结果对重要零部件的较大面积局部表面改性或修复再制造的工程应用具有重要的探索意义。
A nickel-based nano-WC / Co composite cladding layer was prepared on the surface of 45 steel by CO2 laser, and laser lap cladding was performed on the basis of laser single pass cladding. SEM, XRD, EDS and microhardness tests were carried out to compare the microstructure, phase, composition and hardness of laser single lap and lap cladding respectively. The results show that the nickel-based nano-WC / Co composite cladding layer and its lap-cladding layer can be obtained on the surface of 45 steel by choosing suitable laser cladding technology, which can basically eliminate the cracks and holes and metallurgically bond with the matrix. The phase of the cladding layer is γ (Fe-Ni) matrix distribution of WC, W2C-based carbide phase. Among them, the laser micro-hardness of single lap and lap coating are respectively 779.3 ~ 1315.0HV0.1,600.3 ~ 1560.0HV0.1. Although the types of carbide in the single pass and lap coating are the same, the morphology and distribution of the lamellae are obviously different. The shape and distribution of the lamellar claddings are more different than that of the single pass cladding layer Bigger. No matter the laser single pass or lap cladding, there are a considerable number of nanoparticles with particle size ≤100nm, these nanoparticles are most likely to be WC, W2C-based carbide, crack-resistant coating Cracking plays a crucial role in the nano-effect. The results of this study have important exploration significance for the engineering application of large area local surface modification or remanufacturing of important components.