V_2O_5/NiCrBSi激光熔覆层开裂敏感性研究

Investigation on Cracking Susceptibility of Laser-Clad V_2O_5/NiCrBSi Coatings

在 4 5 #钢表面进行了对NiCrBSi合金粉末添加V2 O5的激光熔覆试验。通过优化激光熔覆工艺参数及V2 O5含量的优选 ,得到了质量良好、无裂纹且与基底冶金结合的熔覆层。实验表明 ,随V2 O5含量的增加 ,V2 O5对降低裂纹敏感性的作用逐渐明显直至最终消除裂纹。采用X射线衍射、扫描电镜对显微组织的观察分析表明 ,V2 O5降低熔覆层裂纹敏感性归因于V2 O5能够在快速凝固过程中起到均匀细化枝晶组织、抑制粗大块状脆性硬质相和提高覆层韧性的作用。

The experiments of laser cladding of NiCrBSi alloy powder doped with V_2O_5 were performed. A good finish, crack-free and firm combination with substrate coatings was achieved under a proper amount of V_2O_5-doping and a suitable optimizing technical parameters. It is shown that the proper addition of V_2O_5 can evidently reduce the crack sensitivity of NiCrBSi alloy laser cladding layer. The microstructural and metallographic analyses by a scanning electron microscopy, energy-dispersive spectrometer and X-ray diffractometer suggest that V_2O_5 doped to NiCrBSi alloy powder can refine the microstructure both in grain sizes and their homogeneous distribution, impede the growth of larger crystallites and improve the toughness of coating. Thus the crack sensitivity of coatings can be reduced.