Effect of pre-extrusion on microstructure and mechanical properties of caliber-rolled AZ80 alloy

Abstract

In this paper, pre-extrusion treatment was applied to AZ80 alloy prior to caliber rolling, and microstructural evolution as well as mechanical properties of groove-rolled AZ80 alloy were studied. The results shown that the pre-deformation treatment can enhance the formability of AZ80 alloy and the cracking can be avoided. In addition, the pre-extrusion also resulted in fine grain structure after rolling process. Especially, 8-pass caliber rolling following by pre-extrusion of AZ80 alloy shown uniform and fine dynamic recrystallized (DRX) structure. Besides, the introduction of pre-deformation also promotes more second phases during caliber rolling. Therefore, the mechanical properties shown that the yield strength (TYS), tensile strength (UTS) and elongation after fracture (El.) of pre-extruded AZ80 caliber-rolled bars are 250 MPa, 440 MPa and 15%, respectively, which increased by 72%, 37%, and 88% compared with their as-cast counterparts. The improvement of mechanical properties is attributed to synergy effects of grain refinement, second precipitates strengthening and texture optimization.

Keywords

• Mg alloy
• pre-extrusion
• caliber rolling
• microstructure
• mechanical property