Multi-pass large strain rolling of as-cast AZ31 magnesium alloy

Abstract

As-cast AZ31 magnesium alloy subjected to multi-pass large strain rolling was investigated. A successive rolling process up to three passes was carried out at 370°C with a pass reduction of 30%. Deformation microstructure characteristics prove that the dynamic recrystallisation (DRX) mode changed with the increase of rolling passes. In the first pass, DRX related to twinning played a dominant role. But in the third pass, DRX grains mainly appeared around the pre-existing grain boundaries. The ultimate strength and elongation of rolled sheets after three passes rolling are enhanced by 37 and 39%, respectively, compared to the as-cast alloy. Meanwhile, the tensile fracture mode was ductile fracture which was different from the ductile–brittle fracture of as-cast.

Keywords:

• Multi-pass
• Dynamic recrystallisation
• Grain refinement
• Fracture mode
• Large strain rolling

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (No. 51175059), and also supported by Aeronautical Science Foundation of China (20153663010), China Postdoctoral Science Foundation (No. 2014M551074).