In this work a material model formulation is presented, based on an algorithmic flow rule for small elastic strain, small time steps and plastic incompressibility based on finite kinematics. This leads to an explicit algorithm which is used for a crystal-plasticity-based model formulation for anisotropic elastic ideal viscoplastic materials. This model is applied to simulate the sheet metal specimens with large grains subjected to tensile tests. The experimental results for a bcc Fe-3%Si sample loaded incrementally in tension are taken from literature. The deformation of the individual grains have been measured as well as the local orientation after each loading step. These results are compared to the obtained simulation results of the deformation. Simulations are performed with crystallographic glide on either {110} or {112} systems or both systems simultaneously. First results showed, if no hardening is included the results are already in good agreement, which shows the importance of predicting initially active glide systems correctly.