Hot Rolling of AZ31 Magnesium Alloy to Sheet Gauge

This study details preliminary results of hot rolling trials of AZ31 alloy sheet using a pilot-scale rolling mill. The aim is to design and optimize the hot rolling schedule for AZ31 in order to produce sheet with a fine and homogeneous microstructure. The study examined three different hot rolling temperatures, 350, 400 and 450°C and two rolling speeds, 20 and 50 RPM. A total thickness reduction of 67% was obtained using multiple passes with reductions of either 15% or 30% per pass. The entry temperature of each rolling schedule was kept constant, by reheating the strip between passes. It was found that the microstructure of the AZ31 alloy was sensitive to the rolling temperature, the reduction (i.e. strain) per pass and the rolling speed (i.e. strain rate). A combination of a rolling temperature of 400°C, reduction per pass of 15%, and rolling speed of 50 RPM produced the finest and most homogeneous microstructure. The finite element software ADINA was used to simulate the evolution of the thermal profile of AZ31 sheet during hot rolling. The predicted exit temperatures were in good agreement with the measured temperatures.