Based upon literature data, the thermochemical model of stacking-fault energy in the Fe-Mn-C system was presented. Using the model, the stacking-fault energy of Fe-21Mn-0.4C plus a few percent of added aluminium, copper and chromium was calculated. The stacking-fault energy increased with the contents of aluminium and copper, unlike the case for chromium. The stacking-fault energy of Fe-21Mn-0.4C alloy was affected by its phase composition. When the stacking-fault energy was below 10.7mJ/m2, its phases were y+e. When the stacking-fault energy was 10 to 19.02mJ/m2, its phases were γ+ε+a. As long as the stacking-fault energy was greater than 19.02mJ/m2, it was full of austenite. The change in stacking-fault energy of Fe-21Mn-0.4C, containing a few percent of added aluminium, copper and chromium was not in accord with the mechanical property changes.

Effect of Aluminium, Copper and Chromium on the Stacking Fault Energy and Mechanical Properties of Fe-21Mn-0. 4C TWIP/TRIP Steel. Y.J.Dai, Z.L.Mi, D.Tang, J.C.Lü: Journal of Iron and Steel Research, 2011, 23[4], 32-6