On the role of constitutive model in the forming limit of FCC sheet metal with cube orientations

The effect on forming-limit diagrams (FLD) of an initial cube texture and its evolution was studied using the well-known M-K approach in conjunction with a viscoplastic crystal plasticity model (VPSC). We focused on how the strength of the cube texture affects localized necking. In particular, we addressed the results of Wu et al. Effect of cube texture on sheet-metal formability. Materials Science and Engineering A 2004;364:182-7] who found that a spread about cube exhibits unexpectedly high limit strains. The FLD and yield loci were determined for several spreads about {1 0 0}〈0 0 1〉 with uniform or Gaussian distributions. A smooth transition in predicted limit strains from the ideal cube, through textures with increasing cut-off angles, to a random texture was calculated using the MK-VPSC approach. Results indicate that the constitutive model selected has a critical importance for predicting the behavior of materials that exhibit a qualitative change in the crystallographic texture, and hence, evolve anisotropically during mechanical deformation.