中文摘要：

针对轴类零件的工作条件，采用激光熔覆的方法，在35CrMo钢表面熔覆3540铁基合金粉末和Ni00镍基合金粉末，借助光学显微镜、扫描电镜和显微硬度计等实验设备，研究了熔覆层的形貌、组织特征及显微硬度；通过拉伸实验设计，研究了熔覆层、熔覆层与基体之间的结合强度。研究分析结果表明，两种合金粉末都与基体形成了良好的冶金结合，无明显裂纹或气孔，熔覆层组织致密，晶粒细小。采用3540合金粉末制备的熔覆层的显微硬度高于Ni00合金粉末试样的熔覆层，而在熔覆区与熔合区交界处两种熔覆材料试样显微硬度差别不大，都明显高于基体的硬度．有利于提高零件的耐磨性。拉伸试验结果显示，3540合金粉末和Ni00合金粉末制备试样的平均抗拉强度分别为637．6MPa和614．7MPa，在进行拉伸实验过程中，断口出现在中间熔覆层，说明熔覆层与基体间实现了良好的冶金结合，拉伸过程没有出现明显的屈服现象。

英文摘要：

According to the working conditions of shaft parts, 3540 iron-based alloy powder and Ni00 nickel-based alloy powder were claded on 35CrMo steel surface using laser cladding method. By means of test equipments, such as, OM, SEM and micro-hardness, the morphology, characteristic, and microhardness of cladding layer were studied. The bonding strength between the cladding layer and substrate was studied through tensile experiment design. Research and analysis results show that good metallurgical bonding is formed of two kinds of alloy powder and substrate, and there is no obvious crack or hole, cladding layer with compact structure and small grain size. As cladding material, micro-hardness of the 3540 alloy powder is higher than that of Ni00 alloy powder. While there is little difference between two kinds at the junction of the cladding zone and fusion zone. Both of them are significantly higher than the hardness of matrix, which is helpful to improve the wear resistance of parts. The results of tensile test show that the average tensile strength of 3540 alloy powder layer is 637.6 MPa, while of Ni00 alloy powder layer is 614.7 MPa. In the process of tensile experiment, fracture appears in the middle of cladding layer. It explains that a good metallurgical bonding has been achieved between the cladding layer and the substrate, with no obvious yield phenomenon during the tensile process.