Influence of work-hardening laws on the predictions of forming limit diagrams of polycrystalline steels using a rate-dependent plasticity model

W SIGNORELLI, J; A FOURTY,; A TURNER, P; RAUL EDUARDO BOLMARO; A BERTINETTI, M

Foz do Iguaçu

Congreso; 17o Congresso Brasileiro de Engenharia e Ciência dos Materiais- CBECIMAT.; 2006

Asociaçao Brasileira de Materiais

A rate-dependent plasticity polycrystal self-consistent model and the Marciniak-Kuczynski (MK) approach are applied to predict Forming Limit Diagrams (FLDs) of polycrystalline steels. It is well known that the success of micromechanical modeling depends on both, the relevance of the strain-rate concentration relation and a realistic description of the microstructural features of the material. In this work, different work-hardening laws are implemented to predict FLDs, all them based on physical processes. These laws and theirs influences on the predicted polycrystalline yield locus and therefore on the FLDs, are discussed. Numerical simulations of FLDs are performed for BCC polycrystal sheets, where initial imperfection intensity and orientation, and initial texture are taken into account. The trend of the predicted FLDs shows that, as it was expected, the main differences in the forming limit strains have a correlation with the sharpness of the yield locus near equibiaxial tension. Selecting the adequate law requires not only verifying the overall behavior but also to take into account the various microstructural material features at crystal level.