离焦量对激光熔覆层组织及性能的影响

目的改善40 Cr钢表面性能,提高其表面硬度、耐磨性及耐蚀性。方法利用扫描电子显微镜、显微硬度计、磨损试验机、电化学测试系统等对激光熔覆层组织及性能进行观察和分析。结果离焦量越大,熔覆粉末及基体表面熔化深度越浅,通过控制适当的离焦量可以获得结合良好的涂层;离焦量为110 mm时,激光束的快热快冷作用能获得细小均匀的组织,细晶能保证较高的硬度,耐磨性及耐蚀性均较好。结论 40Cr钢经激光熔覆处理后可显著改善其表面性能,适宜的离焦量有利于获得最佳性能。

Effects of Defocusing Distance on Microstructure and Properties of Laser Cladding Layer

The paper aims to improve surface properties of 40Cr steel and increase its surface hardness, wear resistance and corrosion resistance. The microstructure and properties of cladding layer were researched by scanning electron microscope, microhardness tester, wear testing machine, electrochemical testing system etc. The melting depth of cladding powder and substrate surface got shallower with the increase of defocusing distance. Good combination of coating could be obtained by controlling an appropriate defocusing distance; when the defocusing distance is 110 mm, fine and uniform microstructure could be obtained under rapid heating and rapid cooling effect of laser. High hardness, good wear resistance and good corrosion resistance could be ensured in these fine grains. The surface properties of 40Cr steel can be improved significantly by laser cladding treatment, and the appropriate defocusing distance is beneficial to obtain the best performance.