Effect of extrusion speed on microstructure and mechanical properties of Mg-Al-Ca-Sn alloy

Abstract

Low-temperature and high-speed extrusion of wrought magnesium alloy is an urgent problem. Mg-2.5Al-2Ca-1Sn alloys were extruded at 260 ℃ with different ram speeds (2.0,4.0 and 6.0 mm/s). The effects of extrusion speed on the microstructure and mechanical properties of the alloys were systematically investigated. It's worth noting that all the three extruded alloys were fully dynamic recrystallized (DRXed).With the increase of extrusion speed from 2 mm/s to 6 mm/s, the DRXed grain size are increased from 1.25 μm to 1.94 μm, average second phase particles are augmented from 0.79 μm to 0.89 μm and the volume fraction of second phase increases from 6.4% to 18.6%.The extruded alloys with three different extrusion speeds all show excellent comprehensive mechanical properties because of fine grain size, fully recrystallization and homogeneously dispersed second phase particles. The tensile yield strength (TYS) and ultimate tensile strength (UTS) decreased from 285 MPa,304 MPa to 217 MPa,264 MPa while the elongation increased from 11.4 % to 20 % when the ram speed rised from 2.0 mm/s to 6.0 mm/s.