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

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 dualphase steels. In particular, a hybrid scaling transition law was proposed to reproduce the strain-hardening rate for small deformations for bi-percolant microstructures.

Automated summary

The Hy-MFC model was developed to predict the tensile properties of dual-phase steels based on microstructure parameters. It can be used for a wide range of steels and allows for alloy design and production-line monitoring. By considering the prior austenitic grain size and martensite composition, the model showed good agreement with experimental data, particularly for steels with various martensite fractions. Additionally, electron backscatter diffraction monitoring during tensile tests helped understand the interactions necessary for macroscopic hardening in dual-phase steels, with a proposed hybrid scaling transition law for small deformations.