Study of microstructure-property correlations in dual phase steels for achieving enhanced strength and reduced strain partitioning

This study uses a computational modeling framework for studying the structure-property correlations in Dual Phase (DP) steels. The microstructure-sensitive, dislocation density-based, J 2 plasticity finite element framework simulates deformation in the constituent ferrite and martensite phases and the interplay of various deformation mechanisms. The framework accounts for the effects of the input microstructure, specifically the spatial hetero-geneity of phase distribution, strength differential, and grain size on the evolution of deformation in terms of the local and aggregate mechanical properties. Experimental characterization of the deformed microstructure has been performed using in-situ Digital Image Correlation (DIC). The model predictions are validated with the DIC measurements on DP 600 as well as available data from literature. The simulations reveal significant impact of varying martensite volume fraction and phase strength differential, but not that of martensite island size. New DP microstructures having enhanced strength and reduced strain partitioning are then predicted. Processing routes to achieve such microstructures are proposed.