Microstructural study of cold forged and annealed Mg alloys

Abstract

Cold forging deformations (3 and 8%) were carried out on extruded AZ31 and AZ61 Mg alloys, and subsequent annealing is performed at 573 K for different durations. The microstructure evolution is investigated and further analysed. The results show that the thick lenticular twinning is mainly formed at initial deformation stage and subsequently transforms into narrow band twinning. Compared to AZ31, AZ61 produces broader twins with lower volume fraction in response to 3% cold forging due to Al–Mn phase hindering the twinning activity and plastic deformation. Twin boundary plays an important role in refining grains as it provides the nucleation sites of static recrystallisation. Moreover, as for AZ61, the starting and ending times of static recrystallisation are much later than those of AZ31.

Keywords:

• Magnesium alloys
• Cold forging
• Static recrystallisation
• Grain refinement