Evaluation of friction weld interface of aluminium to austenitic stainless steel joint

Abstract

A type 1050 commercial aluminium was bonded to a type 304 austenitic stainless steel using a continuous drive friction welding process. The bonding interface conditions were evaluated by means of mechanical tests, to measure tensile and bending properties, and ultrasound microscopic observation. The tensile strength of the joints increased as the frictional time increased. High strength joints could be obtained at a frictional time greater than 0.2 s. However, ultrasound microscopy clearly showed that bonding progress occurred from the peripheral region towards the centre of the faying surface and, furthermore, that the frictional time of 0.2 s was not sufficient for complete bonding and much more frictional time was necessary. It is thus difficult to exactly evaluate the joint strength of a soft-hard metal combination by tensile and bending tests alone. Therefore, ultrasound microscopic observation together with mechanical testing is recommended as a convenient method to evaluate such a joint.