Meso-Scopic Analysis of Strain Path Change Effect on the Hardening Behavior of Dual-Phase Steel

To study the anisotropic hardening behaviors of dual-phase steels under strain path changes, a meso-scale finite element analysis was considered with the representative volume elements. For the constitutive model, the Homogeneous yield function based on Anisotropic Hardening (HAH model) was used as a phenomenological constitutive equations to describe complex anisotropic material responses in an efficient way. For the martensite inclusions, three different configurations - elongated, large, and small spherical shapes - with two different volume fractions - 10 and 30% - were assumed. In order to represent strain path changes, two loading conditions were considered: tension-compression and tension-orthogonal tension. The simulation results for tension-compression test showed that the Bauschinger ratio increases as the volume fraction of martensite inclusion increases. For the tension-orthogonal tension test, the hard martensite attenuated the transient flow stress characteristics, which were observed in the single ferritic phase. The effect of hard phase inclusion was analytically explained using a simple one-dimensional analysis based on the elastic-linear plastic theory.