Microstructure And Joint Strength Of Magnetic Pulse Welded Aluminum/Aluminum-Coated Steel Joint

Welding of aluminum and aluminum-coated steel plates was performed using magnetic pulse welding. A1050 pure aluminum and Al-Si-coated steel plates were used in this study. The aluminum and the aluminum-coated steel plates were used for a flyer plate and a parent plate, respectively. The welding interface was observed with an optical microscope, scanning electron microscope and scanning transmission electron microscope. Tensile-shear tests were conducted for evaluation of the joint strength. After the welding, thickness of the aluminum coating slightly decreased at the welded area and Si particles containing in the aluminum coating were refined. The welding interface exhibited characteristic wavy morphology. A banded structure consisting of fine aluminum grains with diameters of approximately 500 nm was formed along the wavy interface. When the welding was performed at longer plate gap condition, void formation was observed in the banded structure and fracture occurred at the welding interface by tensile-shear test. The void formation is considered to lead to a decrease in joint strength.