Friction welding process of 5052 aluminium alloy to 304 stainless steel

Type 5052 aluminium alloy was joined to type 304 austenitic stainless steel via a continuous drive friction welding process. The joint strength increa sed, and then decreased after reaching a maximum value, with increasing fri ction time. Joint strength depended on the size and shape of the tensile te st piece. Friction weldability could be estimated by electrical resistmetry . The process of friction welding between the aluminium alloy and the stain less steel is proposed to evolve as follows: welding progresses from the ou ter to the inner region; an unbonded legion is retained at the centre of th e weld interface with shorter friction time; longer friction time causes th e formation of an intermetallic reaction layer at the weld interface; and t he reaction layer grows as the friction time increases. When the thickness of the reaction layer increased above a critical value, the joint was britt le and fractured at the weld interface. The joint was sound when there was no unbonded region and a thin reaction layer formed along the entire weld i nterface. MST/4250.