Microstructure and Mechanical Properties of Aluminum/Steel Dissimilar Refill Friction Stir Spot Welds
By Peng Li ( Dalian University of Technology), Honggang Dong (Dalian University of Technology), Su Chen (Dalian University of Technology)

Dissimilar materials joining of aluminum alloy to low carbon steel sheets was conducted with refilled friction stir spot welding. The mechanical performance sharply increases when the sleeve plunges into steel sheet, attributing to metallurgic and mechanical bonding between the aluminum alloy and steel sheets. Compared with the joints achieved between aluminum alloy and uncoated steel sheets, the joints made from aluminum alloy and galvanized steel show better weldability and mechanical performance. The maximum tensile/shear fracture load of 4500N was achieved, and the high strength was attributed to the generation of the IMCs layer at sleeve affect zone as thin as 0.68μm due to the low-heat-input feature and Zn coating that blocks the reaction of aluminum and iron.