Characterization of the Formability of Micro Alloyed Steels

The application of high strength low alloyed steels is continuously increasing, especially due to their good formability for deep drawn parts in the automotive industry. For this reason methods to characterize the formability are essential in order to evaluate the forming behavior. In this thesis several methods to characterize the formability are investigated, among them the earing test and tensile test to determine anisotropy coefficients but also the microstructure and texture because these factors play an important role concerning formability.The necessity of this thesis "Characterization of the Formability of Micro Alloyed Steels" derives from the forming process of transmission parts at the ZF Friedrichshafen AG. Here the run-out of guiding disks is frequently not within its tolerance and the reason for these run-out fluctuations needs to be found. It is supposed from earlier work that the material influence is approximately 25 %.There are two main objectives in this thesis. The first one is to find out if the run-out fluctuations depend on the material and the second objective is to work out if an improvement can be achieved by changing the material properties.Corresponding to several formability tests it can be concluded that the run-out fluctuations do not depend on the material. In fact they are most influenced by the forming process with its tools and parameter setup.Regarding the different materials to improve the process it was worked out that a higher deformation ratio during cold rolling increases the γ-fiber content and shows nearly isotropic behavior resulting in a good formability.