Influence of Microstructure Evolution During Twin-Roll Casting on the Properties of Magnesium Sheets

Twin-roll casting of magnesium alloys is seen as a promising processing route to enable further development of advanced magnesium sheets for mass production. The reduction in the number of processing steps to final gauge leads to shorter production times and a decrease in production costs. The new production process for magnesium sheets allows the development of a new generation of magnesium alloys. The microstructure evolution during solidification between the TRC rolls is of great importance and can be influenced by alloy composition, addition of grain refiner or by variation of the process parameter. In the twin-roll casting process, liquid metal is pumped from furnace or cast over a pipe into a tundish. The melt is then dragged into the roll gap of a pair of counter rotating, internally cooled rolls. The metal solidifies upon contact with the cooled rolls is rolled to a strip. Such strips are used as feedstock material for rolling sheets to final gauge. This presentation will discuss the effect of the influencing variables on the quality and performance of Mg sheets on the example of AZ31 sheets. The influence of the strip properties and the rolling process parameters like temperature and degree of deformation on the microstructure, the texture and the mechanical properties of the strip is presented and discussed.