A comparison of the internal stresses in a transformation-induced plasticity-assisted steel and a twinning-induced plasticity steel

An analysis of the loading-unloading behaviour of tensile tests was performed in a transformation-induced plasticity-assisted (TRIP-assisted) steel, duplex high Mn steel (22% Mn-3% Al-3% Si) for a wide range of grain sizes, D. The Bauschinger effect observed during unloading was so strong that plastic deformation was detected before complete unloading was reached. In addition, the yield stress, , or the flow stress, , are related to the grain size according to the Hall-Petch relationship. This behaviour was compared with a twinning-induced plasticity (TWIP), steel (22% Mn-0.6% C). The high levels of internal stresses obtained in both steels can be rationalised on account of the reinforcement of the austenitic matrix by the increasing volume fraction of epsilon-martensite or deformation twins of nanometric thickness.