EFFECT OF DEFORMATION TEMPERATURE ON TENSILE DEFORMATION MECHANISM OF Fe-23Mn-2Al-0.2C TWIP STEEL

Twinning-induced plasticity(TWIP) steel can be classified into three types,Fe-Mn -Al-Si,Fe-Mn-C and Fe-Mn-Al-C steels.Owing to their high strength,superior plasticity and good formability,they have potential applications in automobile manufacturing industry as a new generation of steels.In order to reveal the dependence of deformation mechanism on temperature for Fe-23Mn-2Al-0.2C TWIP steel,microstructural observation,stacking fault energy calculation and tensile deformation experiments were performed at a temperature range from -60℃to 600℃.With increasing the deformation temperature,the strength and elongation to failure of this steel firstly decrease,then increase and finally decrease.And their peak values appear at 300℃during high temperature deformation.As deformation temperature increased from -60℃to 600℃,the stacking fault energy of the steel increases and the deformation mechanism is changed from twining to slipping. Deformation twins with high density appear at lower deformation temperatures,however,they will gradually decrease with increasing temperature.When the sample was deformed at 600℃,only dislocations and dislocation cells appear.High-density deformation twins formed during low-temperature deformation result in the high tensile strength and elongation to failure in this steel.