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.