The mechanical properties of Fe-25Mn-3Si-3Al TWIP steel and the microstructural evolution with temperature were investigated by tensile testing at 298, 373, 473 and 673K. It was found that the strength and elongation decreased with increasing deformation temperature. The stacking-fault energies of the TWIP steel at various temperatures were calculated. It was pointed out that, when the stacking-fault energy was between 21 and 34mJ/m2 and the temperature was 298 to 373K, deformation twinning was the main deformation mechanism. Slip was the predominant deformation mode when the stacking-fault energy was greater than 76mJ/m2 and the temperature was greater than 673K. The stacking-fault energy was found to decrease with decreasing temperature, and lower values of stacking-fault energy promoted deformation twin production and inhibited slip. Deformation twins, formed during plastic deformation, acted as obstacles to dislocations, resulting in high strain-hardening. High elongations and ultimate tensile strengths could be obtained at relatively low temperatures.

Investigations on Temperature Dependence of Mechanical Properties and the Deformation Mechanism of a TWIP Steel. S.Wang, Z.Liu, W.Zhang, G.Wang: J.Xuebao: Acta Metallurgica Sinica, 2009, 45[5], 573-8