ECAP with back pressure for optimum strength and ductility in aluminium alloy 6016. Part 1: microstructure

The microstructure evolution of aluminium alloy 6016 processed by equal channel angular pressing (ECAP) was investigated for different processing parameters. A number of heat treatments, including F, W, O, T4, T6 and T7, were evaluated for workability required to withstand the severe plastic deformation. It was found that this aluminium alloy had limited workability at room temperature in the F, W and T4 tempers, especially at low levels of applied back pressure, while both the O and T7 tempers can be pressed to a very high strain (∼1800%) without failure. Considering that the O temper has better utility for industry because of decreased preparation time, a complete study of microstructure after ECAP processing with and without back pressure was carried out for the O temper. The thermal stability of microstructure after 16 ECAP passes with 200 MPa of back pressure was also studied.