Strain hardening model of twinning induced plasticity steel at different temperatures

• A new twinning model with temperature is presented based on shear-band theory.
• A new dislocation-based model is proposed with temperature-based dislocation generation and annihilation.
• Test data for Fe–22Mn–0.6C TWIP steel is applied to verify the model.

Based on the dislocation and twinning theory, a physical model is developed in this paper to study the influence of temperature on the strain hardening behavior of Twinning Induced Plasticity (TWIP) steel in plasticity deformation. In the proposed model, the dislocation evolution is the competition result between its generation and annihilation controlled by temperature, and the twinning process is related to the operative shear bands. The effect of temperature on twinning is reflected by the parameters of shear-band volume fraction, twinning triggering (initial) strain and twinning driving force. The stress–strain response, hardening rate, and strain hardening exponent of Fe–22Mn–0.6C TWIP steel, deduced from the proposed strain hardening model are verified with experimental data. Furthermore, dislocation density, twinning volume fraction and model parameters are calculated to analyze the influence mechanism of temperature on the mechanical behavior of TWIP steel.