Abstract: Warm forming technology of Mg alloys shows good application prospects, but the warm deformation mechanism needs to be further studied. Using in situ electron back scatter diffraction(EBSD) observation, systematic research and quantitative analysis are carried out on the deformation mechanism of rolled magnesium alloy sheets during uniaxial compression and tensile tests at the temperature range between 100 ℃ and 230 ℃. The mechanical properties of Mg alloy sheets, texture variation and activations of slipping and twinning under different conditions are analyzed, the plastic deformation mechanism of Mg alloy sheet under different conditions and main factors influencing plastic formability are revealed. The results reveal that, to some extent, the change of mechanical property, texture variation and grain orientation evolution are determined by percentage of twinning activations. Mg alloy sheets have higher plastic deformation capability at 170 ℃, activations of large number of pyramidal slipping systems are good for coordinating deformation in thickness direction. According to the achieved deformation mechanisms, several suggestions are proposed for stamping process of magnesium alloy sheets. The warm forming process of magnesium alloy sheets is proposed and several typical magnesium alloy parts are developed using different warm forming technologies.

Key words: Deformation texture, Magnesium alloy sheet, Slipping, Twinning, Warm forming