The influence of dynamic deformation on the mechanisms in TWIP steel

• The significant temperature changes are during the deformation of TWIP steel. • The distribution of twins is associated with the temperature. • Decreasing in twin fraction was observed during dynamic deformation. TWIP steels play a crucial role in the automotive industry and other applications that operate under demanding conditions. As a part of this study, an evaluation of the influence of the strain rate on the deformation mechanism in Fe-21Mn-2.5Al-0.4C (wt.%) steel was developed. The aim of this work was to establish a connection between the deformation mechanisms of dislocation slip and twinning with the strain rate and the actual sample temperature related to the plastic deformation work conversion into heat in TWIP steel. Microstructure characterization involved microscopic observation considering light and electron microscopy methods as well as synchrotron analysis. During dynamic tests at strain rates above 170 s −1 , temperature changes were recorded at subsequent stages of the deformation from the onset of strain localization to the sample fracture. A temperature increase of about 250 °C was observed in the neck of the sample at the moment of cohesion loss. The studies showed that as the strain rate increased, the fraction of twins decreased and the twins became refiner compared to those at lower strain rates. The results of this study constitute a contribution to the understanding of the complex phenomena occurring during the deformation of advanced TWIP steel.