Abstract: Hhe key of welding aluminum to steel is accurate control of heat input, aiming at reducing the brittle inter-metallic compound (IMC) in the interfacial layer. A novel gas metal arc welding (GMAW) process, referred to as double-electrode GMAW, is developed to make it possible to increase the wire melting current while the base metal current is still controlled at a desired level. To accurately control the heat-input, pulse double-electrode GMAW experiments are carried out to joint aluminum wire ER5356 to 304 steel on the basis of optimizing control system and welding parameters. Analysis on the welding joint by means of scanning electron microscope(SEM) and energy dispersive spectrometry (EDS) shows that the IMC layer is less than 10 μm，which is the generally accepted critical thickness. Pulse Bypass-Electrode GMAW, being one of economic low heat-input arc welding methods, is feasible for welding aluminum to steel.

Key words: Dissimilar metals welding of aluminum and steel, Double-electrode gas metal arc welding(DE-GMAW), MIG-brazing