Correlation between the macroscopic behavior and the microstructural evolutions during large plastic deformation of a dual-phase steel

Abstract

The aim of the present work is the analysis of the evolution of the microstructure and texture of a dualphase steel in connection with the macroscopic behavior. Two-stage sequences are carried out in order to investigate the effect of strain-path changes, both at the macroscopic and the microscopic scales. The goal is the achievement of a more comprehensive explanation of the anisotropic behavior under complex strain-path changes for this type of steel (i.e., dual-phase steels). Transmission electron microscopy (TEM) microstructures as well as X-ray diffraction textures are examined after several sequences of simple shear/simple shear loadings. The evolutions of texture are analyzed through comparison with predictions made with the viscoplastic Taylor-Bishop-Hill (TBH) model; its influence on macroscopic values of stress is also quantified. As for the microstructural evolutions, in all investigated cases, it is clear that the dislocation structures which are formed in various grains are strongly dependent on the orientation of the grain, as in the case of previously investigated steel.[1] However, some differences are observed, compared to a simpler single-phase material, which are explained by the differences observed in the initial state and which are then related to the macroscopic behavior.