Improvement of strength and ductility synergy in a room-temperature stretch-formable Mg-Al-Mn alloy sheet by twin-roll casting and low-temperature annealing

Strength and ductility synergy in an Mg-3mass%Al-Mn (AM30) alloy sheet was successfully improved via twin-roll casting and annealing at low-temperature. An AM30 alloy sheet produced by twin-roll casting, homogenization, hot-rolling, and subsequent annealing at 170 degrees C for 64 h exhibits a good 0.2% proof stress of 170 MPa and a large elongation to failure of 33.1% along the rolling direction. The sheet also shows in-plane isotropic tensile properties, and the 0.2% proof stress and elongation to failure along the transverse direction are 176 MPa and 35.5%, respectively. Though the sheet produced by direct-chill casting also shows moderate strengths if the annealing condition is same, the direct-chill casting leads to the deteriorated elongation to failure of 23.9% and 30.0% for the rolling and transverse directions, respectively. As well as such excellent tensile properties, a high room-temperature stretch formability with an Index Erichsen value of 8.3 mm could be obtained in the twin-roll cast sheet annealed at 170 degrees C for 64 h. The annealing at a higher temperature further improves the stretch formability; however, this results in the decrease of the tensile properties. Microstructure characterization reveals that the excellent combination of strengths, ductility, and stretch formability in the twin-roll cast sheet annealed at the low-temperature annealing is mainly attributed to the uniform recrystallized microstructure, fine grain size, and circular distribution of (0001) poles away from the normal direction of the sheet. (C) 2021 Chongqing University. Publishing services provided by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.

Automated summary

Strength and ductility of an Mg-3%Al-Mn alloy sheet were improved using twin-roll casting and low-temperature annealing, resulting in excellent tensile properties and stretch formability.