Rolling Twin Roll Cast Magnesium Strips with Varied Temperature and Degree of Deformation

Abstract

Reducing vehicle weight and emissions by lightweight design is a major goal of the automotive industry. Magnesium as the lightest structural metal bears a significant weight saving potential compared to steels and aluminum. Cast magnesium components are widely used e.g. as engine blocks or gear box houses. The application of magnesium sheets is currently hampered by two main obstacles. The low formability of magnesium sheets requires a high number of rolling passes to roll cast slabs to final gauge which leads into a cost issue for the production of magnesium sheets. An alternative cost efficient production route for magnesium sheets with improved properties is the feedstock production by twin roll casting (TRC). 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 and gets rolled to a strip.This paper reports on results of rolling experiments on twin roll cast strips of magnesium alloy AZ31 (Mg-3Al-1Zn-Mn), which has been cast with different process conditions. 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. By future optimization of process parameters of twin roll casting and the subsequent rolling of the sheets, a serious challenge for conventional materials is within reach.