Study On Compression Deformation And Annealing Recryastallization Of AZ31 Magnesium Alloy

Magnesium is the least dense of all metals being used in practice for structural applications[1-2].The density of the pure magnesium is a 1.74 g/ cm-3, and the density of the common magnesium alloys are (1.3-1.9)g/cm-3. At the same time, magnesium alloys have the highest strength to weigh ratio, good thermal conductivity , electrical conductivity, damping capacity, and good electromagnetic interference shielding property,the property of being easy to manufacture and recyclable, therefore it is widely accepted that magnesium alloy is" the green engineering metals of the 21st century". But magnesium alloy has a hexagonal close-packed (hcp) crystal structure with limited number of operative slip systems at room temperature, so magnesium alloys are normally low formability near the room temperature, and limits the expansion of magnesium alloy applications.The material used in this investigation was as-cast AZ31 magnesium alloy. Before observered the microstructure and XRD analysis, the specimens were compressed to 2.5%, 5%, 7.5%, 10%, 12.5% and 15% reduction. After that, observered the changes of microstructure, hardness and grain sizes of the specimens at different annealing temperature (300℃, 350℃and 400℃) and at different preservation time (30min, 1h, 2h and 5h), in order to find the AZ31 magnesium alloy recrystallization rule. At the same time, observered the fracture and crack expansion.The investigation shows that twinning play an important role in the process of AZ31 magnesium alloy deformation at room temperature and the following recrystallization nucleation. Many twinnings are produced during the process of AZ31 magnesium alloy deformation at room temperature, twinning deformation is the mainly deformation manner, and twinning increases with the deformation increase up to fracture. The sample submit 45°fracture, and belongs to transcrystalline fracture. The brittleness fracture feature can be found by SEM analysis . Annealing temperature, preservation time and compression deformation amount are important factors to recrystallization. Recrystallization can be observered in large deformation amounts (15% and 12.5%) samples, while recrystallization cann't be observered in 5% and 2.5% degree deformation samples during the annealing process. With the annealing temperature increase, the annealing process was quicker. The boundary of twinning is the location of recrystallization nucleation. work-hardening was diminished after the...