Exploring microscopic constitutive properties and deformation behavior of the constituent phases in a Fe-12Mn-8Al-0.8C duplex lightweight steel

This article investigated the microscopic constitutive properties and deformation behavior of the constituent phases (austenite (γ phase) & ferrite (δ phase)) in a Fe-12Mn-8Al-0.8C duplex lightweight steel through a combination of spherical indentation experiments and crystal plasticity (CP) simulations. Microscopic constitutive properties were systematically extracted through the indentation stress-strain, and their orientation dependence were quantified for the first time. In addition, the noteworthy heterogeneity of intergranular stress-strain partitioning in the experimental steel was revealed in detail by CP simulation. The differences in the microscopic constitutive properties of the constituent phases dominate the microscopic deformation behavior during the initial deformation stage, while as the strain level increases, the slip resistance of the constituent phases tends to approach and their micromechanical anisotropy becomes significantly influential on the stress-strain partitioning. It was found that high-intensity accumulated slip induces the formation of intragranular strain localization and transgranular deformation bands. Strain localization and deformation bands have high-intensity plastic energy dissipation, and their distribution affects the fracture mode of the experimental steel. The result reported in this study can provide significant insights for the development of Fe-Mn-Al-C system lightweight steels. • Extracting the microscopic constitutive properties of constituent phases in a Fe-12Mn-8Al-0.8C duplex lightweight steel and successfully quantifying their micromechanical anisotropy. • Clarifying the effect of micromechanical anisotropy of the constituent phases on the stress-strain partitioning of the duplex lightweight steel. • Revealing the relationship between the stress-strain partitioning and failure mechanism of the duplex lightweight steel.