Grain refining of magnesium alloy AZ31 by rolling

Magnesium alloy is the lightest metal that can be employed for structural use. However, it is commonly recognized that magnesium possesses poor formability at room temperature because of its hexagonal closed packed structure. It is then highly desirable to refine the grain structures in order to apply superplastic forming technique. Among the hot forming processes for refining grain structure, the most practical technique is rolling combined with suitable heat treatment which can be scaled for large bulk sheet or plate sample fabrication. Results of grain refining by this processes are presented. Processed AZ31 was studied with optical and transmission electron microscopy as well as X-ray diffraction. Tensile tests at room and high temperatures were also performed using the Instron machine, and their properties are correlated with the microstructures.