Assessment of a Micro-Macro Modeling of the Bending and Unbending of Multiphase Steel Sheets

A study was conducted to assess micro-macro modeling of the bending and unbending of multiphase steel sheets. Four types of multiphase steel sheets, used in the automobile industry were investigated in the study. The four alloys presented different phase proportions and a different strength measured in uniaxial tension. Bending and unbending investigations were carried out using a laboratory set up, designed specifically to exert a bending moment on the test samples. The bent and unbent samples were sufficiently wide to ensure planar curve, while samples were clamped and held on pneumatic suspensions so that the bending angle was prescribed under unconstrained translational motion. It was demonstrated that valid predictions at the scale level of individual phases required a proper definition of the effective shear moduli μeff. The results show that the mean-field model predicts a Bauschinger effect when individual phases undergo isotropic hardening.