Plastic deformation behavior of a thermo-mechanically processed AZ31 magnesium alloy under a wide range of temperature and strain rate

摘要

Effects of texture evolution and grain refinement induced by Equal Channel Angular Pressing, ECAP, on mechanical responses of an extruded AZ31 magnesium alloy are investigated. Uniaxial compression loading is carried out under a wide range of temperature (77 K-423 K) and strain rate (10(-4) s(-1) -3000 s(-1)) along pressing direction (PD), transverse direction (TD), and normal direction (ND). The s-shape strain hardening curve which is the main characteristic of twin-dominated deformation shows a strong dependency on testing temperature and strain rate in the ECAPed material so that during loading at the highest temperature (423 K) and the lowest strain rate (10(-4) s(-1)), s-shape hardening is no longer present. However, measured texture under the mentioned loading condition reveals crystal reorientation due to twinning which implies that the absence of concaved-up stress-strain curve is not necessarily indicative of suppression of twinning. On the other hand, the measured texture during high temperature dynamic loading suggests saturation of twinning at smaller strains. Schmid factor maps, in agreement with Visco-Plastic Self Consistent (VPSC) models, suggest the higher activity of twinning and basal slip in plastic yielding of the extruded and ECAPed AZ31, respectively. (C) 2016 Elsevier B.V. All rights reserved.