Mechanical properties at room temperature of an Al–Zn–Mg–Cu alloy processed by equal channel angular pressing

Tensile tests were conducted to evaluate the influence of equal-channel angular pressing (ECAP) on the mechanical properties at room temperature of overaged Al 7075-O alloy. ECAP processing was performed using route BC at different temperatures and number of passes, i.e. different processing severity conditions. The maximum load (Fmax) recorded during the last pass of each ECAP path considered in this study is a very good estimation of the processing severity. The mechanical properties were studied in terms of the balance between tensile strength and ductility. In the processed Al 7075-O alloy, the grain size was reduced down to ∼150 nm. Consequently, tensile testing at room temperature revealed a significant increase in the maximum tensile strength after ECAP with respect to the as start material. In the present study, as the processing severity increases with the number of ECAP passes or with the decrease in processing temperature, there is a consistent trend of increment in ultimate tensile strength with minor decrease in uniform plastic elongation respect to the first ECAP pass at room temperature. This is in contrast to the behaviour after more severe plastic deformation conditions, where an increase in strength together with a strong decrease in elongation would be expected.

• The microstructure and the yield stress obtained after ECAP processing is determined mainly by the processing severity. • The processing severity has been estimated by the maximum load recorded during the ECAP processing. • Increase from 3 to 8 ECAP passes at 130 °C produces a marked improvement in yield stress without significant loss of elongation. • Processing at low temperature limits dislocation recovery during processing, decreasing the elongation at fracture.