Si和Zn对铝/钢异种金属熔钎焊接头界面组织的影响

Effects of Si and Zn on interface microstructures of aluminum/steel welding-brazing joint

采用脉冲旁路耦合电弧MIG熔钎焊方法用ER4043铝合金焊丝对5052铝合金/镀锌钢异种金属进行搭接焊,通过扫描电镜、能谱仪、X射线衍射仪对所获得的铝/钢连接界面进行了分析与研究。结果表明:焊接接头焊趾处是一个Zn的富集区,通过对该区域组织进行分析发现,焊趾处的物相由靠近钢侧的Fe2Al5Zn0.4和焊缝中的Al-Zn固溶体组成。焊缝中的Si元素参与了界面处化合物层的反应,并生成了Al8Fe2Si三元金属间化合物,该三元金属间化合物沿着焊缝侧金属间化合物Fe Al3的边缘分布。进一步线扫描发现:Si元素在整个界面反应层中有明显富集现象。此外,在测试结果的基础上对Fe-Al-Si三元金属间化合物的生长过程进行探讨。

The dissimilar metals of 5052 aluminum alloy/galvanized steel were joined with lap joint by pulsed double electrode gas metal arc welding-brazing with ER4043 filler metal. The interfacial microstructures of the joints were analyzed by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry. The results show that a zinc-rich zone locates at the weld toe,which is mainly composed of Al-Zn solid solution at the weld seam side and Fe2Al5Zn0.4 at the galvanized steel side. Si element in weld seam involves in metallurgy reaction of intermetallic compound formation and the Al8Fe2Si ternary phase is found, the phase Al8Fe2Si forms along FeAl3 side. The results of linear scanning indicate that Si atom obviously aggregates in the intermetallic compound layers. Further, the formation process of Fe-Al-Si ternary intermetallic compound was discussed on the basis of the test results.