Development of a New Wrought Magnesium-Aluminum-Manganese Alloy AM30

A new wrought magnesium alloy, AM30 (Mg-3 pct Al-0.4 pct Mn), has been developed. Compared to the current workhorse commercial wrought magnesium alloy AZ31 (Mg-3 pct Al-1 pct Zn), the new AM30 alloy has 20 to 50 pct higher maximum extrusion speed, up to 50 pct ductility improvement at temperatures up to 200 °C, with similar yield and tensile strengths. The tensile behavior of AM30 and AZ31 magnesium alloy tubes suggests a moderate temperature forming range of 100 °C to 175 °C in which strain hardening offsets plastic instability until fracture by cavity coalescence occurs. The AM30 alloy has slightly better formability than AZ31 at room and moderate temperatures, due to higher strain-hardening rates (dσ/dε) and exponents (n). Microstructural evaluation indicates that twinning is the major deformation mechanism for these alloys at room and moderate temperatures in addition to slip mechanisms. Dynamic recrystallization (DRX) is observed at temperatures greater than ∼150 °C, which causes local instabilities to occur, leading to failure.