Toward Development of Strong and Formable Magnesium Alloy Sheets with Bake-Hardenability

Abstract

To enable broader applications of magnesium alloy sheets, one requirement is to achieve comparable strength-formability balance with that of aluminum-based alloys. Based on the review of recent studies on precipitation hardening of microalloyed magnesium alloys, we propose the usage of age-hardenable alloys to overcome the strength-formability trade-off in magnesium alloy sheets. Precipitation hardening has not been actively used in commercial wrought magnesium alloys because of their poor age-hardening responses. However, recent studies have shown appropriate selection of microalloying elements leads to a substantial enhancement of the kinetics of age-hardening. We found Mg-Ca-X (X = Al, Zn) dilute alloys show promising age-hardening characteristics for bake-hardenable alloy sheets that may be used as a substitute for 6xxx aluminum alloy sheet for weight reduction. Such alloys show excellent room temperature stretch formability, and substantial strengthening to ~240 MPa can be achieved by a short-term aging at low temperatures: 170°C for 20 min.