QT-500球墨铸铁表面激光熔覆镍基合金的组织与性能

利用DL-T5000型二氧化碳激光器在QT-500球墨铸铁表面熔覆镍基合金,分析了激光熔覆层的显微组织,测试了其显微硬度及磨损性能。结果表明:所制得熔覆层组织致密、无裂纹,与基体形成了良好的冶金结合。从熔覆层表面到基体热影响区,组织依次为大量的树枝晶、等轴晶、树枝晶。熔覆层的硬度较基体提高了5倍,熔覆层的总磨损率大约为基体的1/6。熔覆层耐磨性能增强的主要原因是镍基合金与涂层元素镍、铬等固溶强化和碳化物等析出相的强化作用。

Microstructure and properties of surface laser clad Ni-base alloy layer on QT-500 ductile cast iron

Laser cladding of Fe-based alloy on ductile cast iron QT-500 substrate was carried out by DL-T5000 CO2 laser.The microstructure,microhardness,and wear resistance of the laser clad layers were analyzed and tested.The results show that the clad layer has compact and flawless microstructure that was integrated metallurgically bonded with ductile cast iron QT-500 substrate.Microstructure of the clad zone consists of branch crystal,equiax crystal and branch crystal in turn from the clad layer surface to heat-affected zone of ductile cast iron QT-500 substrate.The microhardness of the laser clad layers is increased 5 times than that of the ductile cast iron QT-500,and the wear rate is just about one sixth of the QT-500 substrate.The improvement of abradability are mainly attributed to the solution strengthening of Ni and Cr elements and the precipitation hardening of carbides.