Physical metallurgy of Mg AZ80 alloys for forging applications

The Dow Chemical Company originally developed Mg AZ80 alloy in the 1950's for forging applications. The physical metallurgy and microstructural makeup of AZ series alloys can be quite varied and are dependent on alloy content, casting parameters, cooling rate, heat treatment, and thermomechanical processing. Early attempts to improve the ductility of this alloy focused on reduction of the as-cast grain size and volume fraction of brittle second phase particles. The mechanical properties and microstructure of Mg AZ80 alloys were studied after different thermomechanical processing to assess its suitability for the forging applications. The stability of secondary phases was evaluated in this alloy by modeling phase equilibria and examining its microstructure using a range of experimental approaches. The recrystallization behaviour of the alloy was studied to optimize homogenization treatments, deformation processing and the microstructure of the as-cast billets to achieve the full potential of AZ80 in application for automotive wheels.