Effects of Al‐Ni powder addition on dissimilar friction stir welding between AA7075‐T6 and 304 L Auswirkungen der Al‐Ni‐Pulverzugabe beim artfremden Rührreibschweißen zwischen AA7075‐T6 und 304 L

Friction stir welding between AA7075‐T6 aluminum alloy and 304 L stainless steel sheet metal was performed with the addition of Al−Ni powder between the joining interfaces to increase the joining performance. The welding tool was rotated at 200 min⁻¹ to 800 min⁻¹ with the constant traverse speed of 25 mm/min. The resulting joint interfaces were analyzed using a field emission‐scanning electron microscope and energy‐dispersive x‐ray spectroscopy analysis. The tensile strength was greater for the Al−Ni powder added specimens at the lower tool rotational speeds. The tensile strength of 360 MPa was obtained for the 'with‐powder' specimen as compared to 220 MPa for the 'without‐powder' specimen at the 200 min⁻¹ tool speed. Electron microscope images of the stir zone showed a significant mixing of the Al−Ni powder with the base materials, increased contact at the interface, which resulted in increased joining strength at the lower tool rotational speeds. However, based on the images, intermetallic compound that may contribute to the joining strength in the vicinity of the interfacial region was not detected.