The deformation twinning of magnesium alloys is known to induce compressive fracture at room temperature. However, the formability in multi-axial compressive stress conditions has scarcely been investigated, nevertheless their importance for plastic working processes such as forging and extrusion. In the present study, biaxial compressive plastic behavior and compressive forming limit of AZ31 magnesium alloy at room temperature were investigated using a unique biaxial compression testing machine. The uniaxial and biaxial compression tests along proportional strain paths were conducted, and thus the influence of strain path upon the mechanical properties and the forming limit were discussed. The compressive forming limit indicated clear strain path dependency. It was also found that the forming limit was influenced by the plastic anisotropy. The adaptability of the typical forming limit criterion to the compressive forming limit was also discussed.
