Constitutive model of the TWIP effect in a polycrystalline high manganese content austenitic steel

摘要: The TEM study of our steel with a high manganese content reveals that mechanical twining (TWIP effect) occurs during the deformation at room temperature. Microtwins are organised into parallel stacks and two systems sequentially activated in each grain. They participate to they strong obstacles for dislocations other twins, leading decrease effective grain size. Thus, TWIP provides alloy very good ductility hardening rate. Our constitutive modelling deduced from model proposed by Bouaziz Guelton [4] integrates this typical organisation microtwins. Twinning is quantified partial volume fraction twins system. A nucleation law microtwins introduced which depends on local stress relaxation due pre-existing twins. flow dislocation density, evolves dynamical recovery mean free path (MFP). MFP takes account twin boundaries forest dislocations. strain calculated adding contributions glide twinning accounting orientation To treat polycristal, behaviours different orientations mixed assuming step increment elastic energy stored same was successfully applied describe properties alloy, sizes. Some microstructural parameters yet fitted. This leads an insufficient prediction evolution microstructure. In further developments, we expect introduce numerical simulation results characteristics (thickness, critical resolved shear twinning) experimental rate nucleation.