铸铁表面激光熔覆哈氏合金C276组织及性能

Microstructures and Properties of Hastelloy C276 on Cast Iron Surface by Laser Cladding

目的提高铸铁表面耐磨、耐腐蚀性能。方法采用激光熔覆技术在铸铁表面制备哈氏合金C276涂层,采用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)研究其显微组织、化学成分、相组成。通过摩擦磨损试验机和电化学试验站,对基体和熔覆层的摩擦磨损性能及耐腐蚀性能进行测试。结果熔覆层中有析出性气孔,未见裂纹。在激光高温热源的作用下,熔覆层中的合金元素扩散到了铸铁基体中,且过渡平稳,形成了良好的冶金结合,在界面处形成了马氏体和莱氏体。熔覆层主相为γ-Ni及Ni_6Mo_(6C)、M_(6C)(Ni_(3)Mo_(3C)、Ni_(2)W_4C)等碳化物。熔覆层从底部到顶部依次形成了平面晶、胞状晶、柱状树枝晶、发达树枝晶、胞状树枝晶和少量等轴树枝晶。熔覆层的平均硬度为370HV_(0.2),平均摩擦系数为0.28,1 h的磨损量为0.081 g,自腐蚀电位E_(corr)为-0.32 V,自腐蚀电流密度J_(corr)为8.51×10^(-7) A/cm^(2)。基体的耐磨性较差,腐蚀倾向较大,平均硬度为180HV_(0.2),平均摩擦系数为0.34,1 h的磨损量为0.318 g,自腐蚀电位E_(corr)为-0.79 V,自腐蚀电流密度J_(corr)为3.31×10^(-6)A/cm^(2)。结论在铸铁表面采用激光熔覆技术制备C276哈氏合金涂层,成形效果良好,耐磨性能和耐腐蚀性能显著提高。

This paper aims to improve the wear resistance and corrosion resistance of cast iron surface.The cladding layer of Hastelloy C276 was prepared on the surface of cast iron by laser cladding.The microstructure,chemical composition and phase constitution were studied by scanning electron microscope(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD).The friction and wear properties and corrosion resistance of the substrate and cladding layer were tested by friction-wear test machine and electrochemical workstation.It was found that precipitated pores existed in the cladding layer,but no cracks.Under the action of laser high temperature heat source,the alloying elements in the cladding layer diffuse into the cast iron substrate,and the transition is smooth,forming a good metallurgical bonding.Martensite and ledeburite are formed at the interface.The main phase of the cladding layer was composed ofγ-Ni and carbides such as Ni6Mo6C and M6C(Ni_(3)Mo_(3)C,Ni_(2)W_(4)C).From the bottom to the top of the cladding layer,planar crystals,cellular crystals,columnar crystals,developed dendrites or cellular dendrites and a few equiaxed dendrites were formed in this order.The average microhardness of the cladding layer was 370HV0.2,the average friction coefficient was 0.28,and the wear amount was 0.081 g for 1 h.The self-corrosion potential of the cladding layer was-0.32 V,and the self-corrosion current density was 8.51×10^(-7) A/cm^(2).The wear resistance of the substrate was poor,and the corrosion tendency was greater.The average microhardness of the cladding layer was 180HV0.2,and its average friction coefficient was 0.34,and the wear amount was 0.318 g for 1 h.The self-corrosion potential of the cladding layer was-0.79 V,and self-corrosion current density was 3.31×10^(-6) A/cm^(2).The C276 Hastelloy coating prepared by laser cladding on the surface of cast iron has good molding effect,and the wear resistance and corrosion resistance are significantly improved.