Joining phenomena during friction stage of A7075-T6 aluminium alloy friction weld

Abstract

This paper describes the effect of friction welding conditions on joining phenomena during the friction stage of type 7075-T6 aluminium alloy (A7075) friction welds. The friction torque had wear and seizure stages until the initial peak torque when A7075 was welded under high friction speed and low friction pressure, i.e. 27 · 5 rev s^?1 and 30 MPa. Initial seizure and joining began at the central region (centre axis) of the welded interface, and extended towards the peripheral region (outer surface). On the other hand, when A7075 was welded under high friction speed and high friction pressure, i.e. 27 · 5 rev s^?1 and 90 MPa, almost no wear stage existed before the initial peak torque. Initial seizure and joining began at the peripheral region of the welded interface and extended towards the central region. Then, the friction torque reached an initial peak torque when the welded interface was joined completely and upsetting of both base metals started. As a conclusion, the joining mechanism of A7075 friction welding was similar to that of low carbon steel.