The methods of processing to produce fine grain structure in magnesium alloys: An overview

Abstract

Magnesium alloys have gained importance for aerospace, automobile, and biomedical applications in the last few years due to their high strength to weight ratio. It is well known that magnesium possesses lower formability due to the insufficient slip systems available for deformation, especially during the forging process. There are many ways by which improvement in formability is possible. One of the methods is the refinement of grain structure and subsequently achievement of superplasticity by optimizing strain rate and temperature. The present article discusses the overview of the processing methods to produce fine grain structure in magnesium alloys. These methods include the conventional to severe plastic deformation processes. Conventional methods for refinement of grain structure include casting and hot rolling. Severe plastic deformation processes include caliber rolling, multi-directional forging, equi-channel angular pressing, high-pressure torsion, friction stir processing, and high ratio extrusion methods. The process described with associated equations for strain and the impact of these processes on the microstructural aspects of magnesium alloys is explained in this paper. It showed that the different process parameters with a different kind of alloy give rise to differences in the refinement of grain structures which further changes the formability of magnesium alloys. This paper also describes the advantages and limitations with usefulness in industrial practices of the processing methods to produce fine grain structure in magnesium alloys.