Effect of Mn and Zr Microalloy on the Recrystallization and Solidification Behavior of Cast-Rolled Al-Mg-Si Alloy

In this work, the effect of Mn and Zr composite microalloying on the microstructure evolution and solidification behavior of Al-Mg-Si cast-rolled alloy was investigated. The results show that the grains of Al-Mg-Si alloy were refined by adding Mn and Zr elements, and the second phase of AlFeSi is more dispersed. Furthermore, the recrystallization behavior of the alloy is inhibited by Mn and Zr microalloy, retaining the fibrous edge structure and avoiding/reducing the edge segregation during the casting and rolling process. In the manufacturing process of aluminum alloys, Fe contamination is an inevitable issue. Iron is prone to combine with elements such as Al and Si, resulting in the aggregation of secondary phases that can adversely affect the material’s properties. Thermodynamic calculation demonstrates that Mn element decreases the α-AlFeSi phase, with the α-AlFeMnSi phase becoming the primary iron-containing phase. When Mn and Zr elements are combined, there is a slight increase in the formation temperature and total mass of the Mg₂Si phase and Al₃Zr phases. Benefiting from the aforementioned merits, the mechanical properties of the cast-rolled plates are improved.