Mechanical behavior of polycrystal metal is often significantly deviated from various assumptions made in the classical plasticity theories. Not only the anisotropy hardening but also Bauschinger effect becomes evident in complex loading scenarios, which may play important role during metal forming operations. Several phenomenological and crystal plasticity models have been developed and reported in the literature, which is targeted to capture these “unconventional” behaviors that the classical plasticity theory cannot explain. Our focus in this study is on the crystal plasticity model, which can explain the behavior of materials in consideration of the slip system and the microstructure of the material.
Among various crystal plasticity models reported in the literature, the ΔEVPSC model was chosen for the current investigation. This model can be used not only as a stand-alone code but also as user material subroutine for finite element analysis. Model characterization was performed using the dislocation density-based RGVB hardening model for a chosen low-carbon mild steel. The steel sample is also referred as EDDQ (extra deep drawing quality) and is used in various automotive components.
The RGVB hardening model parameters were calibrated by fitting with various experimental stress-strain curves resulting from monotonic uniaxial stress-strain curve and a set of experiments in which strain path changes. In addition, loading unloading reloading experiment and three-point bending with a pre-strain test was performed using the calibrated parameters. The experimental trend of decreasing Young''s modulus was qualitatively captured by the model. Moreover, the experimental trend in which the increase in pre-strain leads to increase in the springback amount was captured by the model. The overall predictive accuracy of the model is reasonable. Several modelling suggestions, which can potentially improve the quantitative prediction accuracy, are discussed.