The evolution of LPSO phase and its influence on grain size during cooling free forging

Abstract

In this paper, the deformation behavior of the LPSO phase of Mg-Gd-Y-Zn-Zr and its influence on the grain size are studied during the cooling free forging deformation. Studies have shown that cooling free forging can refine different forms of LPSO phases. The lamellar and block LPSO phases are kinked and broken during the deformation process. The kink angle and the number of kinks of the lamellar phase are greater than that of the block phase. With the increase of the cooling pass, the fragmentation of the lamellar phase is more violent. The kink and broken of the LPSO phase significantly refined the grain size by dividing the grains and promoting dynamic recrystallization. The grain size has dropped significantly from 113 μ m in one pass to 12 μ m in three passes. Uniform fine structure improves alloy mechanical properties through the Hall-Petch principle. The ultimate tensile strength of three-pass alloy reaches 323.2 MPa, the yield strength reaches 239.9 MPa, and the elongation reaches 17.1%.

Keywords

• Mg-RE
• LPSO phase
• kink
• mechanical properties