镁铝异种材料点焊接头显微组织研究
Research on microstructure of Mg/Al dissimilar materials spot weld joint
魏强
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作者单位：南昌航空大学
中文关键字：Mg/Al异种材料；电阻点焊；显微组织
英文关键字：Mg/Al dissimilar materials; Resistance spot welding; Microstructure
中文摘要：采用三相次级整流电阻焊机，对2mm厚AZ31B镁合金和LF6铝合金进行电焊试验，并采用扫描电镜（SEM）、能谱分析（EDS）、X射线衍射（XRD）和显微硬度测试等方法，对Mg/Al异种材料电阻点焊接头进行了研究。试验结果表明，点焊熔核呈帽形，熔核组织形态以细小的等轴树枝晶为主，熔核边缘存在少量的柱状晶。Mg/Al点焊中Al原子的扩散速度远远大于Mg原子，在靠近镁侧形成了 Mg17Al12金属间化合物层，其硬度高达251HV。
英文摘要：Three-phase secondary rectification welding machine was used to weld 2mm thick AZ31B magnesium alloy and LF6 aluminum alloy. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to observe the microstructure of spot welding joints, and microhardness was tested. The results showed that a cap-like nugget was obtained in Mg / Al dissimilar materials spot welding. Small equiaxed dendrites oriented microstructure distributed in the center of nugget morphology, and at the nugget edge present small amounts of columnar grain. In the Mg / Al dissimilar materials resistance spot welding the diffusion rate of Al atoms is fasten than the Mg atoms, and intermetallic compound layer Mg17Al12 was observed in the weld nugget near Mg side. Its hardness achieved 251HV.