One Pass Large Draught Rolling of Magnesium Alloy Sheet near Room Temperature by High Speed Rolling

摘要

AZ31B and AZ80A magnesium alloy sheets are rolled up to 60% reduction in one pass rolling below 200°C at the rolling speed of 1000m/min and 2000 m/min without heating rolls. The enhanced ductility in high speed rolling results from temperature rise due to plastic work. During rolling of a sheet, heat is generated by plastic deformation and by friction between the material and rolls. Meanwhile the heat transfers from the material to cold rolls. With increasing the rolling speed, the duration where the material and the rolls are in contact becomes shorter. This results in effective temperature rise of the sheet during rolling. So fracture or cracks due to the low-temperature brittleness can be suppressed considerably by high-speed rolling. The rolled and quenched sheets showed fully recrystallized microstructure at higher reduction. The microstructure was homogeneous throughout the thickness. The finest recrystallized grain size was 2.2μm for AZ31.