Improving the Mechanical Properties of Mg-5Al-2Ca-1Mn-0.5Zn Alloy through Rotary Swaging

Abstract

To meet the demand for more extensive applications of Mg alloys, a Mg-5Al-2Ca-1Mn-0.5Zn alloy without RE was prepared in this paper, and its mechanical properties were further improved by conventional hot extrusion and subsequent rotary swaging. The results show that the hardness of the alloy decreases along the radial central region after rotary swaging. The strength and hardness of the central area are lower, but the ductility is higher. The yield strength and ultimate tensile strength of the alloy in the peripheral area after rotary swaging reach 352 MPa and 386 MPa, respectively, while the elongation remains at 9.6%, exhibiting better strength–ductility synergy. The grain refinement and dislocation increase caused by rotary swaging promoted strength improvement. The activation of non-basal slips during rotary swaging is an important reason for the alloy to maintain good plasticity while improving strength.

Structural Phenomena Introduced by Rotary Swaging: A Review

“…Nevertheless, given its favorable stress state, RS has successfully been applied to Mg (alloys) too. The importance of the activation of non-basal slip systems within Mg alloys during RS processing was emphasized by, e.g., Li et al [139], who used room temperature RS to deform a MgAlCaMnZn alloy and achieve a strength of almost 400 MPa, as RS contributed significantly to the refinement of Al 8 Mn 5 second phase precipitates. When subjected to deformation, Mg primarily exhibits twinning and the generation of stacking faults (all together with the generation of dislocations and the activation of slip systems), which gradually results in grain refinement; Yang et al [140] performed a detailed study of the interactions of structural phenomena (i.e., twinning, stacking faults, and dislocations) within a MgLi alloy; in order to thoroughly map the occurring structural features, they gradually applied room temperature RS with a total swaging ratio of up to 0.32 in very low increments (swaging ratio of ~0.02 in a single pass).…”