Effect of Sn distribution on tensile property and stretch formability of Mg-3Al-0.4Mn (mass%) alloy sheet

The effect of Sn on tensile properties and stretch formability of a rolled Mg-3Al-0.4Mn (mass %) alloy was investigated. Annealing at low temperatures led to the formation of fine Mg₂Sn particles in the Sn-containing alloy sheets, which enhanced work-hardenability. The low-temperature annealed sheet showed a fine grain structure and weakly aligned (0001) poles, resulting in a moderate 0.2 % proof stress of 166 MPa along the rolling direction, good limiting dome height of 7.8 mm, and in-plane isotropy of tensile properties in an Mg-3Al-0.4Mn-1Sn alloy sheet. However, relatively large particles were distributed in a low-temperature annealed Mg-3Al-0.4Mn-3Sn alloy sheet. This promoted the formation of cracks and resulted in a loss of stretch formability. Annealing at a high temperature was also conducted to dissolve Sn element into the matrix, while the solid-solution of Sn was not effective in improving the tensile properties and stretch formability.