Effect of Magnesium Content on Microstructure and Mechanical Properties of Twin-Roll Cast Aluminum Alloys

High magnesium containing aluminum alloys are preferred in applications where high strength and good formability are of importance. However, enhanced Mg content in AlMg alloys leads to increased solidification range which makes these systems difficult to be produced by twin-roll casting. In this study, AlMg alloys were produced by twin-roll casting with different Mg contents up to 5.2 wt% and processed to obtain soft annealed 1 mm thick samples. The effect of Mg content on the microstructural evolution during twin-roll casting as well as downstream processes and mechanical properties of soft annealed 1 mm thick samples was investigated. Addition of Mg leads to coarser grain structure in as-cast strips and finer grain structure after intermediate annealing as well as soft final annealing. At the same time, enhanced Mg content provides higher yield and tensile strengths as well as lower elongation.