激光熔覆汽轮机转子表面涂层的显微组织研究

摘要

For shaft journal remanufacturing of steam turbine rotor by laser cladding,Fe-based alloy cladding experi-ment was performed by a 2 kW laser diode with coaxial powder feeder,and the temperature near the working point was monitored during the process of laser cladding. The microstructure morphologies,phase structure and composition of the laser remanufacturing layer were analyzed by scanning electronic microscopy(SEM),the X-ray diffraction(XRD) and energy dispersive spectrometer(EDS). The results show that the heating of laser cladding is relatively concentrat-ed,and the maximum temperature is not more than 70 ℃. The microstructure of Fe-based alloy cladding layer is hom-ogeneous and compact. The cladding layer is well combined with the substrate without gas holes and cracks. The mi-crostructure of the cladding layer consists of alloys(Fe,Cr,C)and CrC phases. The microstructure of the cladding lay-er is composed of a typical supersaturated solid solution dendrites and interdendritic multiple eutectic carbides,and el-ement mutual infiltration is found between substrate and laser cladding layer.%针对激光熔覆再制造汽轮机转子轴颈，采用2 kW半导体激光器进行同轴送粉的激光熔覆Fe基合金试验，并在激光熔覆过程中对加工点附近的温度进行监控。利用扫描电镜（SEM）、X射线衍射仪（XRD）、X射线能量色散谱仪（EDS）研究了熔覆层的显微组织形貌、相结构与成分。结果表明，激光熔覆加热集中，检测部位的最高温度未超过70℃，整个修复过程平稳。Fe基合金熔覆层组织均匀、致密，与基体冶金结合，没有微观裂纹与气孔等缺陷。熔覆层组织主要为（Fe、Cr、C）合金与CrC两相。熔覆层的组织主要为典型的过饱和固溶体枝晶与枝晶间多元碳化物共晶组成，激光熔覆层与基体熔合过程中产生了元素互渗。