Interface structure and mechanical properties of Fe/Al dissimilar lap joints formed by friction stir welding using an adjustable tool

Abstract

Friction stir welding (FSW) of aluminum alloy and steel using an adjustable tool was carried out, which can effectively control the thickness and uniformity of the IMC layer. The continuous and uniform IMC layer as thin as about 0.4 µm was obtained, owing to the strong material flow introduced by the adjustable probe. The strength of the welded joints increased as the thickness of the IMC layer decreased in the range of 0.9 µm to 0.4 µm. However, when the thickness of the IMC layer was below 0.4 µm, it became nonuniform and discontinuous, decreasing the joint properties. In this study, a high-strength Fe/Al dissimilar lap FSW joint was obtained, ascribed to the more uniform and continuous thin IMC layer.