镀锌钢表面光纤激光宽带熔覆铝合金涂层研究

Study on Fiber Laser Cladding of Aluminum Alloy on Galvanized Steel with Square-Spot

采用经整形的矩形光纤激光光斑和配套的宽带送粉装置,实现了在镀锌钢板表面熔覆AlSi12合金涂层。通过光学显微镜、扫描电镜和X射线衍射仪观察熔覆层成形、缺陷以及金属间化合物层组织,结果表明熔覆层中的主要缺陷是裂纹。在熔覆层与母材界面处的金属问化合物层中发现裂纹,熔覆中的热输入量与裂纹长度成正比。通过增加激光功率或降低熔覆速度可以有效减小熔覆层中气孔的最大直径并减少气孔数量,熔覆层界面处组织为Al-Fe-Si系统金属间化合物。激光功率的降低或熔覆速度的增加,可以有效降低金属间化合物层最大厚度,采用适当的熔覆工艺参数控制金属间化合物层厚度,可以有效避免裂纹的生成。

Adopted by a square-spot laser beam and supported by powder feeding device with simuhaneous powder feeding technique, a AlSil2 alloy clad was produced on the surface of galvanized steel. The morpholog： of cladding layer, defects and organization of intennetallic phase （I.M.P.） were analyzed by OM, SEM and XRD. The results indicated that the main defect in the clad was cracks, and they were only found in the interface of clad. It was found that the crack length increased with the energy input during the cladding process. By raising the laser power or reducing the velocity, the maximum diameter of pores in the cladd dropped significantly as well as the amount of them. The I.M.P consists of Al-Fe-Si system intermetallics. The maximum thickness of it went down with the increasing of velocity or the decreasing of laser energy. The cracks could be avoided by contrulling the thickness of I. M.P. with optimized cladding parameters.