扫描速度和Ni含量对高速激光熔覆层特性的影响

Effects of Scanning Speed and Ni Content on the Characteristics of High-speed Laser-clad Coating

本文采用6 kW光纤激光进行了铁基合金高速激光熔覆试验研究,探讨了扫描速度和Ni含量对熔覆层宏观质量的影响,采用金相显微镜表征了高速熔覆层的组织结构特征,采用MM-U10G型磨损试验机和CS350型电化学工作站分别测定了熔覆层的耐磨性和耐蚀性。结果表明:通过材料成分和工艺优化,制备的高速激光熔覆层具有良好的宏观质量,表面Ra小于12.5μm,熔覆层无气孔和裂纹等缺陷。不同扫描速度的激光熔覆层显微组织晶粒随着速度的提升而更加细小,组织性能更优。扫描速度700 mm/s时的一次枝晶间距约为速度10 mm/s的1/10,约为速度100 mm/s的1/5。随着Ni含量的增加,熔覆层的硬度虽有所下降,但均大于HV570,耐蚀性均明显优于45钢,在保证一定硬度的前提下,熔覆层可达到与304不锈钢相当的耐蚀性。研究成果在泵阀、轴类零件和牌坊等产品的制造和再制造领域具有广泛的应用前景。

A 6 kW fiber laser was used to investigate high speed laser cladding(HSLC)of iron-based alloy in this paper.The influence of scanning speed and Ni content on macro-quality of the laser-clad coating was discussed.Optical microscope was adopted to reveal the microstructure and phase structure of the HSLC coatings.Furthermore,a MM-U10 G type friction and wear tester and a CS350 type electrochemical workstation were used to measure the wear resistance and corrosion resistance of the HSLC coatings,respectively.Results show that,the optimized HSLC coatings presented good macro-quality,such as,small surface roughness(<12.5μm),lack of pores and cracks.The microstructure grains of laser clad coating with higher scanning speeds become smaller and have better properties.The primary dendrite spacing at the scanning speed of 700 mm/s is about 1/10 of the speed of 10 mm/s,and about 1/5 of the speed of 100 mm/s.With the increase of Ni content,the hardness of cladding layer decreased,but it was greater than HV570.Corrosion resistance is obviously better than 45 steel and equivalent to 304 stainless steel while good wear resistance is guaranteed.The research results have wide application prospects in the manufacturing and remanufacturing of pump valves,shaft parts and memorial arch.