Microstructure of friction weld interface of 1050 aluminium to austenitic stainless steel

Abstract

Type 1050 aluminium was bonded to type 304 stainless steel by a friction welding procedure. The aluminium was greatly deformed, and the grains were elongated and refined near the weld interface. The stainless steel was slightly deformed and partly transformed at the faying surface from austenite to martensite owing to hard friction. As a result, the hardness of both materials in the vicinity of the weld interface was higher than that of the base metals. Constituent elements of both materials had interdiffused through the weld interface, and some intermetal1ic compounds, Fe₂Al₅, FeAl, and Fe₃Al, were formed at the weld interface. It was presumed by estimating with metallographic observation that the welding temperature was lower than the lowest eutectic temperature in the metal system. So the friction welding mechanism of this system was based on interdiffusion of each constituent in the solid state.