Vertical twin roll casting process of Mg alloy with high aluminium contents

This paper describes the twin roll casting technology of magnesium alloys that contain relatively high weight ratio of aluminium, such as AM60 AZ91, AZ121. The magnesium alloy sheets were cast by a vertical type roll caster to manufacture relatively high strength Mg alloys with high aluminium contents. The influences of such process parameters as materials of roll, casting temperature, and roll speed are ascertained. A simple method of predicting the convection heat transfer coefficient between casting rolls and molten metal is introduced. The microstructures of cast magnesium alloy sheets were microscopically observed to investigate the effects of roll casting conditions on crystal growth in the cast products. It is found that fabrication of Mg alloys with high aluminium contents was possible at a roll speed of 90m/min with a vertical type rollcaster, The grain size of the manufactured wrought magnesium alloy sheet was about 30 micrometers due to rapid solidification in the proposed process.