Deformation mechanism and softening effect of extruded AZ31 magnesium alloy sheet at moderate temperatures
(1. School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063, China;
2. School of Materials Science and Engineering, Hunan University, Changsha 410082, China)
2. School of Materials Science and Engineering, Hunan University, Changsha 410082, China)
Abstract: The flow stress behavior of extruded AZ31 magnesium alloy sheet was investigated by means of compression tests at temperatures between 473 and 523 K and strain rates ranging from 0.001 to 1.0 s-1. The deformation activation energy of the sheet in extrusion direction (ED) was calculated, and the relationship between the softening effect and deformation mechanism was elucidated by optical microscopy and transmission electron microscopy. The results show that when the extruded AZ31 magnesium alloy samples were compressed at moderate temperatures in ED direction, the deformation activation energy is 174.18 kJ/mol, which means that dynamic recrystallization (DRX) is the main softening effect and is controlled by cross slip of thermal active dislocation. Dislocation slip is the main deformation mechanism in moderate-temperature deformation process except twinning. The main DRX effect at moderate temperatures can be considered to be continuous dynamic recrystallization accommodated with twinning DRX.
Key words: AZ31 magnesium alloy; deformation mechanism; active energy; dynamic recrystallization