Microstructure and properties of Mg-3Sn-1Mn (wt%) alloy processed by a novel continuous shearing and rolling and heat treatment

A novel semisolid continuous shearing and rolling process for producing Mg-3Sn-1Mn (wt%) alloy strip was proposed, microstructure and properties of Mg-3Sn-1Mn (wt%) alloy strip processed by the proposed process and heat treatment was investigated. For each condition, at least three tensile tests were performed. Under strong cooling and shearing actions caused by the rotating roll and the fixed shoe, eruptive nucleation, direct globular grain growth and dendrite arm breakage took place in the roll-shoe gap, which causes the formation of fine spherical or rosette primary grains. When the casting temperature was 690 °C, and the roll speed was 0.052 m s−1, Mg-3Sn-1Mn (wt%) alloy strip was produced. The microstructures of the strip are mainly composed of fine spherical or rosette grains. After deep rolling, the grains of the strip were elongated, the textures were formed in the deep-rolled strip. The ultimate tensile strength (UTS) of the deep-rolled strip is 276±3 MPa, and the elongation (EL) is 6.3±0.1% in the rolling direction (RD). After solution treatment at 480 °C for 13 h and aging at 300 °C for 12 h, the Mg2Sn phase distributes homogeneously in matrix microstructure and strengthens the mechanical properties, the UTS and EL of the deep-rolled strip reach 305±3.3 MPa and 7.8±0.12% in the RD.