通过GS-TFL6000型横流CO2激光器, 采用YG813硬质合金粉末和自行设计的TiC/Co50复合粉末作为预置层, 在40Cr刀具基材表面进行了激光熔覆实验研究。借助光学显微镜和X射线衍射仪分析了复合粉末成分配比和激光工艺参数对刀具表面修复层宏观形貌和组成与结构的影响。结果表明, 采用YG813硬质合金粉末无法得到良好熔合质量的修复层, 而自行设计的复合粉末在激光功率为4.5 kW, 扫描速度为400 mm/min时, 预置层经高能激光束辐照后可以得到表面熔合质量良好的修复层。显微组织结构分析显示, 修复层组织细密, 无明显气孔和裂纹缺陷; 不同激光工艺参数下的修复层物相组成基本相同, 基体相主要由γ-Co和少量Ni3(Cr, Fe)固溶体组成, 大量颗粒状TiC增强相弥散分布在基体组织中。

Laser repairing experiments for 40Cr steel cutting tools were carried out by GS-TFL 6000 CO2 laser cladding equipment, and YG813 hard alloy powder and three kinds of self-designed composite powder with TiC/Co50 were selected as preset layers. The macro-morphology and microstructure of laser repairing coatings at different composition ratio of composite powder and laser process parameters was characterized by optical microscopy and X- ray diffraction. The results showed that the better coating can be obtained with TiC/Co50 composite powder preset layer by high-energy laser beam irradiation, and appropriate laser process parameters are laser power 4.5 kW and laser scanning speed 400 mm/min. However, the roughness of laser repairing coating with YG813 powder is bigger than that with TiC/Co50 composite powder. The microstructure of laser repairing TiC/Co50 coating cross section is well-distributed, and no obvious pores and cracks in it. The XRD results shown that the phase composition is same, the matrix phase is mainly composed of γ-Co and a small amount of Ni3(Cr, Fe) solid solution, and a large number of reinforced phase with TiC particulates is dispersed in the matrix.