纯Al与镀锌钢板TIG熔-钎焊接头的界面结构特征

Interface structure of TIG welding-brazed joint of pure aluminum and zinc-coated steel

采用Al-Si药芯焊丝,研究了纯Al与镀锌钢板的TIG熔-钎焊工艺,分析了接头的界面结构特征及其性能。研究结果表明,在40～60 A的低焊接电流条件下,即可成功实现纯Al与镀锌钢板的TIG熔-钎焊。当焊接电流为40 A时,只有在焊缝/Fe母材结合界面存在Al-Fe-Si三元金属间化合物,厚度约为2 μm,靠近Al母材的焊缝金属由α-Al树枝晶和网状Al-Si共晶组成。当焊接电流增大时,焊缝/Fe母材结合界面金属间化合物中的Fe含量明显增加,可能发生了由Al_9Fe_2Si_2向Al_8Fe_2Si的转变,厚度增至约5 μm,Fe母材表面铺展边沿的焊缝金属中也出现大量长条状金属间化合物,而焊缝金属中心位置至Al母材之间区域没有金属问化合物。Al/Fe接头的抗拉强度系数接近80%,接头断裂发生在Al母材热影响区位置,没有发生在界面金属间化合物层的情况。

Dissimilar metal joining of aluminum to zinc-coated steel by TIG welding-brazing using flux cored wire was investigated.The studied results showed that these materials can be successfully joined by TIG welding-brazing at the currents of 40-60A.When the current was 40 A, only there exists an Al-Fe-Si ternary intermetallic compound with a thickness of about 2μm at the weld/Fe bonding interface.The weld metal close to the Al base metal consists of α-Al dendrites and reticular Al-Si eutectics.With welding current being increased,the Fe content in the intermetallic compound at the weld/Fe bonding interface increased and there may exist a transformation of A19 Fe_2 Si_2 to Al_8 Fe_2 Si under this condition, and the thickness of the intermetallic compound reach up to 5μm.There are a large amount of strip-like intermetallic compounds in the weld metal close to the spreading edge,while no intermetallic compound is found in the zones from the weld center to the Al base metal.The tensile strength of Al/Fe joint was close to 80% of that of the Al base metal.The fracture happens at the heat affected zone of the Al base metal, instead of at the interface intermetallic compound.