Hot deformation behavior and workability characteristic of a fine-grained Mg-8Sn-2Zn-2Al alloy with processing map

The hot deformation behavior of a fine-grained Mg-8Sn-2Zn-2Al (TZA822, in wt%) alloy was investigated in the temperature range of 150-350 degrees C and the strain rate of 0.01-10 s(-1) employing thermomechanical simulator. In most of the cases, the material showed typical dynamic recrystallization (DRX) features i.e., a signal peak value followed by a gradual decrease or to reach a steady state. The work hardening rate was found to increase with decreasing temperature and increasing strain rate, while strain rates had great effects on work hardening behavior. Meanwhile, the constitutive analysis indicated that cross-slip of dislocations was likely to be the dominant deformation mechanism. In addition, the processing map at the strain of 0.1-0.7 showed two stability domains with high power dissipation efficiencies and the optimum hot working parameters for the studied alloy was determined to be 350 degrees C/0.01 s(-1) and 350 degrees C/10 s(-1), at which continuous DRX (CDRX) and discontinuous DRX (DDRX) as main softening mechanism. The instability regions occurred at 200-250 degrees C/10 s(-1) and the main flow instability mechanism was twinning and/or flow localization bands, which were prone to induce cracks and caused in-consistent mechanical properties of the alloy. (C) 2019 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.