稀释率对镍基合金激光熔覆层组织和性能的影响

Influence of Dilution on Microstructure and Properties in Ni based Laser Clad Coating

采用激光熔覆法将Ni60熔覆层沉积在中碳钢基体上,采用能谱、电子背散射衍射技术和扫描电镜分析了稀释率对化学成分、相组成、微观结构演化的影响,并且还测量了激光熔覆后熔覆层的显微硬度分布。结果表明,激光熔覆的过程参数对稀释率有很大的影响,稀释率随激光功率、扫描速度的增加而增加,随送粉量的增大而减小。稀释率的变化能引起熔覆层中析出相类型和形态的改变,过高的稀释率会抑制硼化铬、碳化铬的析出,并减少共晶组织含量。由于硼化铬、碳化铬、Ni-B-Si共晶的减少和熔覆层中铁含量的增加,Ni60熔覆层的硬度从1 000HV0.5下降到600HV0.5。

In this study, Ni60 coatings have been deposited on mild steel substrates using laser cladding. The dilution effect on the chemical characterization, the phase formations and the microstructural evolutions were analyzed by using energy dispersive spectroscopy, electron backscatter diffraction and scanning-electron microscopy. The results indicate that the processing parameters have great influence on dilution in laser cladding. The dilution increases with the increase of laser cladding power and scanning speed, whereas with the increases of powder feeding rate, the dilution is reduced. The dilution variations in laser cladding can modify the type and morphology of the phase. High dilution suppress the primary phase and diminish the proportion of Ni-B-Si eutectics. By reducing of the amount of chromium boride, chromium carbide and Ni-B-Si eutectic, excessive iron contents, the hardness of Ni60 coating decline from 1 000HV0.5 to 600 HV0.5.