Optimizing Transformation-Induced Plasticity to Resist Microvoid Softening

Many high-performance steels that are critical for energy-efficient, lightweight designs rely on transformation-induced plasticity (TRIP) to achieve superior combinations of strength and ductility/toughness. Further development of these alloys will require greater optimization of the metastable (retained) austenite phase responsible for TRIP. Considering the complex nature of TRIP and its effects on ductile fracture, an integrated computational materials engineering (ICME) approach to materials optimization is desired. In this work, we report the results of a large series of micromechanical finite element calculations that probe the interaction of TRIP and void-mediated ductile fracture mechanisms. The simulations identify the optimal austenite stability for maximizing the benefit of TRIP across a wide range of stress states. The applied stress triaxiality significantly influences the microvoid growth rate and the computationally determined optimal stability. The simulation results are compared with existing experimental data, demonstrating good agreement.