钢铝异种金属的低能量焊接法

传统电弧焊法焊接钢铝异种金属时，会在过渡区生成Fe-Al金属间化合物层，其硬度高、韧性低，降低了接头性能。基于机械作用的低能量电弧焊接方法，在短路期间采用机械作用促使熔滴过渡，热输入量低，可有效抑制金属间化合物的晶体长大，该种工艺可以采用常规4047焊丝实现铝和镀锌板的焊接。对焊缝金属的金相分析表明，钢一侧为钎焊，铝一侧为熔焊。通过金相及扫描电镜观察发现，在焊缝金属和镀锌板的界面区形成的金属间化合物层，主要成分为Fe2Al5和FeAl3，金属间化合物层的厚度减小到3～4 μm。在界面区主要含有3种元素，分别为Fe、Al和Si，没有Zn元素。拉伸试验表明，焊缝接头在铝合金热影响区断裂，且强度值高于铝合金母材强度的70%，接头强度基本满足使用要求。

Low Energy Welding Technology in Bonding Steel with Aluminum

In welding steel with aluminum, the intermetallic compound of Fe and Al will appear, which will decrease the tenacity, increase the hardness, and lead to a bad joint performance. A new kind of low energy input (LEI) welding technology is introduced and it can be used to weld steel with aluminum by using 4047 wire. The whole welding process is a circulation process of “arcing-short circuit”, in which the heat input is reduced greatly. By using this technology, brazing is located on the steel side and arc fusion welding on the aluminum side. From the metallic phase and scanning electron microscope, a continuous and compact intermetallic compound layer with a thickness of 3~4 μm can be observed, which forms in the interface region of the welding seam metal and the galvanized sheet. The main components in the layer are Fe2Al5 and FeAl3, without Zn. Tensile strength tests prove that the joint breaks in the heat affect zone, and the strength is higher than 70% that of the aluminum alloy base material. So, LEI can lead to a good performance joint.