Abstract
The paper mainly focuses on calculating and comparing a mathematical model of the deformation behaviour at high temperatures. Analysis of the high-temperature plastic behaviour of lean medium-manganese steel 0.2C3Mn1.5Si was carried out in the temperature range of 900–1200 °C and the deformation rate in the range of 0.01–10 s^–1 to the maximum value of the true strain 0.8. Microstructural changes were observed using light optical microscopy (LOM) and scanning electron microscopy (SEM). The effect of hot deformation temperature on true stress, peak stress, and the true strain was evaluated using the flow curves. Based on these results, transformations in steel were discussed from the dynamic recovery and recrystallisation point of view. Furthermore, a present model, taking into account the Zener-Hollomon parameter, was applied to predict the true stress and strain over a wide range of temperatures and strain rates. Using constitutive equations, material parameters and activation energy for the investigated steel could be derived. Results demonstrate the use of the model for lean medium-Mn quenching and partitioning steel (Q&P) compositions in hot deformation applications with acceptable accuracy.

Key words
deformation curve, hot deformation, microstructure, manganese, true strain, true stress

Full text (2657 KB)