Deformation behaviour of ultrarine-grained 7075 aluminium alloy

Samples of a 7075 aluminium alloy were prepared by the equal-channel angular pressing (ECAP) technique. The channel had a 10 mm x 10 mm cross section and an angle of 90 degrees. A total of six passes was performed using route B-C. The ECAP processing was carried out at 120, 170, and 220 degrees C. The ECAP-processed samples with grain sizes between 300 and 2000 nm were machined to tensile specimens with their tensile axis parallel to the pressing direction. Uniaxial tensile tests were carried Out using an INSTRON testing machine at temperatures between room temperature and 300 degrees C at a constant crosshead speed giving an initial strain rate of 10(-3) s(-1). The maximum stress decreases with increasing testing temperature. The elongation to failure increases with increasing testing temperature. The values of the yield stress, the maximum stress (ultimate tensile stress), and the elongation to failure depend also on the ECAP processing conditions.