在不同扫描速度下采用 5 kW横流 CO2激光器对高铬铸铁轧辊进行激光熔覆试验。使用光学和扫描电子显微镜对熔覆层的组织形貌和成分进行分析, 并对涂层的截面硬度进行测试。结果表明, 通过激光熔覆技术, 可以在高铬铸铁轧辊表面制备出得到高硬度的涂层, 并对产生裂纹的原因进行了分析。随扫描速度的增加, 熔覆层的组织由细小变为粗大, 涂层的气孔率变大, 产生裂纹的倾向增加。涂层与基材为冶金结合, 涂层的显微硬度达到 62 HRC, 速度的最优值为 2.5 mm/s。

The laser cladding of high-Cr cast iron roll was performed under different scan speed witha transverse flow CO2 laser with the power of 5 kW. The microstructure and composition analysis of the cladding layer were made by optical and scanning electricmicroscope. The microhardness in the cross section and substrate were measured. The results revealed that the coating with highhardness can be obtained on the surface of high Ni-Cr cast iron roll via laser cladding technology. The reasons led to the crack on thecladding layer was also introduced.The grain size of the cladding layer became more and more finer with the increasing scan speed.What's more, the porosity of the cladding layer was larger and the crack sensity increased too with the increasing scan speed.Thecladding coating was metallurgically bonded to the substrate. The microhardness of the coating can be amouted to as high as 62 HRC.The best scan speed in the present study is 2.5 mm/s.