Material characterization for forming technology
User report - Forschungsgesellschaft Umformtechnik mbh
With the help of the indentation method according to DIN SPEC 4864, the strength of the surface layer and the core of components can be obtained, and small components can also be examined with regard to their material properties. In addition to the tensile strength RIm, the course of the yield strengthRIp0.2 and the associated yield curves are also determined. These parameters can now be used to optimize the forming process of the component by means of an FEM simulation. This results in more accurate simulation results and thus potential savings in tool production or tool finishing.
The Forschungsgesellschaft Umformtechnik mbh (FGU) is an engineering company in the field of forming technology in Stuttgart. As a spin-off company of the Institute for Forming Technology at the University of Stuttgart, FGU has been networking current science with industry for more than 30 years. One of the focal points of the services is forming simulation. For this purpose, various FEM programs are used to map the processes from solid to sheet metal forming. An essential part of the forming simulation is the mapping of the used material in the material model.
Particularly in the field of solid sheet metal forming, very small blanks are often used which cannot be characterized by the usual methods such as compression or tensile tests. In some cases, it is then necessary to resort to pre-stages of the blank in order to obtain blanks of manageable size. However, this can lead to a deviation of the actual material properties, since forming or other process steps are not mapped. Another challenge is the characterization of gradients in the component, if these components have a hardened surface layer over a relatively small penetration depth.
With the indentation method according to DIN SPEC 4864, very small components can be well characterized. In addition, the boundary layer can be directly examined for its strength. This can significantly improve the simulation accuracy. Both the comparative tensile strength RIm and theRIp0.2 comparative yield strength are determined and offer an added value to the classical re-evaluation according to EN ISO 18265. The resulting yield curve contains the input parameters necessary for the FEM simulation.