Investigation and mean-field modelling of microstructural mechanisms driving the tensile properties of dual-phase steels

Abstract A hybrid composite medium-field (Hy-MFC) model was developed to predict the tensile properties of dual-phase steels under monotonic loading based on physical parameters of the microstructure (phase fraction, chemical composition, and grain size of each phase). The Hy-MFC model is intended to be applicable to a wide range of fully ferritic to fully martensitic steels, particularly for alloy design and production-line monitoring. Accounting for the prior austenitic grain size as well as the chemical composition of martensite in the model resulted in good agreement between the modelling and experimental data for the investigated industrial and ternary steels with various martensite fractions. In addition, electron backscatter diffraction monitoring performed during tensile tests allowed to understand the different interactions necessary to reproduce the macroscopic hardening of dual-phase steels. In particular, a hybrid scaling transition law was proposed to reproduce the strain-hardening rate for small deformations for bi-percolant microstructures.