Influence of Tool Geometry on Microstructure and Mechanical Properties of a Friction Stir Welded 7075 Aluminum Alloy

The effectiveness of a friction stir welded joint is strongly dependent on several process parameters such as the tool geometry, including the height and the shape of the pin and the shoulder surface of the tool. In this study, two pin parameters, namely the pitch dimension (1.25 and 0.75 mm) and the helix angle (right and left helices), are varied in order to study their influence on the microstructural, hardness, and tensile properties of friction stir welded 6 mm thick aluminum alloy 7075. The results reveal that the best combination has been obtained when welding with a pitch dimension of 0.75 mm using a right helix pin.