Mechanical behavior of low carbon steel subjected to strain path changes:Experiments and modeling

The mechanical response of a low carbon steel under complex strain path changes is analyzed here in terms of dislocation storage and annihilation. The mechanical tests performed are cyclic shear and tensile loading followed by shear at different angles with respect to the tensile axis. The material behavior is captured by a dislocation-based hardening model, which is embedded in the Visco-Plastic Self-Consistent (VPSC) polycrystal framework taking into account the accumulation and annihilation of dislocations, as well as back-stress effects. A new and more sophisticated formulation of dislocation reversibility is proposed. The simulated flow stress responses are in good agreement with the experimental data. The effects of the dislocation-related mechanisms on the hardening response during strain path changes are discussed

Mechanical behavior of Mg subjected to strain path changes:Experiments and modeling

Two-step tension tests with reloads along different directions are performed on rolled Mg alloy sheet at room temperature. The experimental yield stress at reloading is systematically lower than before unloading. Such a behavior is captured by a microstructure-based hardening model accounting for dislocation reversibility and back-stress. This formulation, embedded in the Visco-Plastic Self-Consistent (VPSC) model, links the dislocation density evolution throughout the deformation with hardening. The predicted results agree well with the experimental data in terms of flow stress response and texture evolution. The effects of texture anisotropy and back-stress on the mechanical response during the strain path change are discussed

A theoretical study of the effect of the double strain path change on the forming limits of metal sheet

The present paper aims at a theoretical study of the forming limits of a sheet metal subjected to double strain path changes by using as reference material the AA6016-T4 aluminium alloy sheet. The simulation of plastic instability is carried out through the Marciniak-Kuczynski analysis. The initial shape of the yield locus is given by the Yld2000-2d plane stress yield function. The strain hardening of the material is described by the Voce type saturation law. Linear and several complex strain paths involving single and double strain path changes are taken into account. The validity of the model is assessed by comparing the predicted and experimental forming limits under linear and selected one strain path change. A good accuracy of the developed software on predicting the forming limits is found. A sensitive analysis of the influence of the type and the value of the double prestrain on the occurrence of the plastic flow localization is performed. A remarkable effect of the double strain path change on the sheet metal forming limits is observed.114sciescopu

Modeling of the Mechanical Response During Reversal Shear Loading:Application to Steels

A hardening model that considers the dislocation reversal‐related mechanisms is applied to predict the mechanical behavior of low carbon (LC) and twinning‐induced plasticity (TWIP) steels under forward–reverse shear test with various pre‐strain levels. The predicted results are presented in terms of stress–strain response and texture evolution. It is shown that the proposed model, embedded in the visco‐plastic self‐consistent (VPSC) framework, well captures the changes in the reloading yield stress and the hardening evolution due to the strain path reversal. The contributions of the different mechanisms are also discussed