Investigation of 7075 aluminum alloy TIG welding joint using 7075 aluminum alloy wire before and after heat treatment

7075 aluminum alloy butt welding was carried out by TIG welding with self-made 7075 wire. The effects of different currents on the microstructure and mechanical properties of the joint before and after heat treatment were studied. Before heat treatment, the strength and elongation of the joint are 274.84 MPa and 6.3%, which are determined by the presence of a large number of second phase precipitates with different shapes. After heat treatment, the tensile strength and elongation are increased to 511.75 MPa and 13.76%. Since most of the second phase has been dissolved, the grain size becomes the decisive factor. The fine grain size and more sufficient recrystallization degree make the mechanical properties of the low-current joint better.