Cyclic response of fine grain 5056 Al–Mg alloy processed by equal-channel angular pressing

Abstract

The cyclic response of the fine-grain 5056 Al–Mg alloy processed by severe plastic deformation through equal-channel angular pressing (ECAP) is investigated in plastic strain controlled experiments with a plastic strain amplitudes ε pl ranged from 5×10 −4 to 10 −2. This material exhibits a fairly high yield stress of 400 MPa, however, its strain controlled properties appear worse than those of the O-temper specimens as is evidenced by the Coffin–Manson plot. The cyclic softening was found to be small with a visible tendency to increase with ε pl. It is emphasized that the mechanical properties of the ECAP materials are strongly influenced by their susceptibility to strain localisation. It is shown that the engineering characteristics obtained after ECAP can be significantly improved during short time annealing at moderate temperature (150°C, 15 min) after fabrication. This annealing is supposed to recover the most heavily distorted grain boundary region, facilitating the dislocation mobility to carry out the imposed plastic strains.