Drastic Improvement in Dissimilar Aluminum-to-Steel Joint Strength by Combining Positive Roles of Silicon and Nickel Additions

•Gas tungsten arc welding of aluminum alloy to steel was performed using Si-containing filler bars and Ni plating.•Simultaneous additions of Si and Ni drastically increased the joint strength from 44 to 93 MPa.•Intermediate metals changed microstructures of intermetallic compounds layer, resulting in an improvement in joint strength.