A micro mechanical study on DP600 steel under tensile loading using Lemaitre damage model coupled with combined hardening

Selecting an appropriate material behavior is considered to be one of the most important parts of simulating mechanical tests in dual phase (DP) steels. In this study, Lemaitre damage model besides combined isotropic/kinematic hardening is used for finite element modelling of DP600 steel in uniaxial tensile loading. Plane strain analysis was performed on a representative volume element selected from the scanning electron microscopy (SEM) picture which was captured from surface of the specimen. Calibration of material parameters for ferrite phase obtained good results in stress-strain diagram and damage distribution in simulation which verified with experimental results. Simulation and also SEM analysis showed that almost all damaged regions were in ferrite/martensite boundary and especially between two martensite islands that are close to each other; these regions are in main shear bands areas. At the end, a parametric study was done to determine the effect of morphology and distribution of martesite phase on DP steel behavior under tensile loading. The results showed that regular morphology of martensite phase gave better results in terms of energy required for fracture and damage distribution than irregular morphology.