激光熔覆高碳铁基合金组织性能研究

Microstructure-Property of Laser Cladding High Carbon Fe-Based Alloy

通过激光熔覆技术,制备了不同碳含量的高碳铁基合金熔覆层。采用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)及能谱仪(EDS)、显微硬度计和电化学工作站,对熔覆层的显微组织、物相构成、碳化物形貌及元素分布、硬度和耐蚀性能进行了较为系统的研究。实验结果表明,高碳铁基合金熔覆层组织均匀致密。当熔覆层中碳含量为2.5%(质量分数,下同)时,其组织为初生γ-Fe胞状树枝晶及晶间M7C3型碳化物;当熔覆层中碳含量为4.5%时,其组织为等轴树枝晶形貌的初生M7C3型碳化物及共晶(M7C3+γ-Fe)。随着熔覆层中碳含量的增加,其平均显微硬度由913.96HV提高至到1421.54HV;同时,熔覆层耐蚀性加强。

High carbon Fe-based alloy with various C contents is deposited by laser cladding technology. Optical microscope （OM）, X-ray diffraction （XRD）, scanning electron microscope （SEM） with energy dispersive spectrometer （EDS）, microhardness tester and electrochemical workstation are used to investigate the microstructure, phase, carbide morphology and composition distribution, microhardness and corrosion resistance of the cladding. The results show that the microstructure of high carbon Fe-based alloy is uniformed and compacted. With 2.5% C （mass fraction） in the cladding, the microstructure consists of primary y-Fe with columnar dendrite morphology and inter-dendrite M7C3 carbide. With 4.5 % C in the cladding, the microstructure consists of primary M7 C3 carbide with equiaxed dendrite morphology and eutectic （M7 C3--7-Fe）. With the content of C increasing, the average microhardness of the cladding increases from 913. 96 HV to 1421. 54 HV. Meanwhile, the corrosion resistance of the cladding is improved.