A strategy for synthetic microstructure generation and crystal plasticity parameter calibration of fine-grain-structured dual-phase steel

摘要

This study aims to establish a strategy for bridging the microstructure and mechanical properties of fine-grain-structured dual-phase steel. A complete workflow is built up commencing with the microstructure observations and characterization in both phase and grain levels by assorted experimental techniques. An assessment criterion is proposed to quantitatively examine the representativeness of synthetic microstructure models in terms of the refined microstructural features including phase fraction, grain size, grain shape, and texture for each phase of the steel. The criterion is employed to define a two-step optimization procedure for building the synthetic microstructure model for the dual-phase steel with nanoscale grain size. The crystal plasticity model is employed to describe the material deformation behavior. The corresponding material parameters are calibrated by an inverse approach combining the nanoindentation test and the macroscopic uniaxial tensile test. The simulation with the calibrated parameters and the synthetic microstructure model gives an excellent prediction of the Lankford coefficient of the dual-phase steel. Benefiting from the strategy, a virtual laboratory is conducted to investigate the micro-structure sensitivity on the mechanical properties, which serves a basis for the microstructure design with desired properties.