Metals under the microscope
Gone are the days when the blacksmith worked metals on the basis of his own skill and experience. Today, before any metal-working takes place, materials scientists simulate on the computer how a metallic component will behave along the process chain. In the case of car body parts, for example, they study how the metal will react to rolling, deep drawing and welding and how the final component will behave in a crash. The research scientists can simulate reality very closely with their computations of many materials, such as aluminum and conventional steels. But some materials with special properties such as high-strength steels and magnesium are less straightforward. A particularly problematic feature of magnesium, for example, is that the alignment of minute metal crystals in its microstructure creates a texture which is not amenable to rolling. To overcome such problems, scientists first compute the properties of the crystallites which constitute the material. They then draw conclusions on the behavior of the entire component through several interim stages. Various approaches are applied for making the model-based transition from the crystallite scale to the macro-level. Research scientists at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg apply a self-consistent model: They observe a single test crystallite in an environment which matches the mean properties of all the other crystallites. By contrast, the scientists at the Max Planck Institute für Eisenforschung (Iron Research) MPIE in Düsseldorf unravel the metal’s properties with the aid of improved Taylor models. “There are pros and cons to both approaches,” explains Hermann Riedel, Head of Business Unit “Material-Based Process and Component Simulation” at the IWM. “We have already made good progress with the self-consistent model for magnesium, while the simulation successes achieved for aluminum are based on modified Taylor models.” Recently the Fraunhofer and Max Planck scientists started to share their experimental facilities and to combine their models. Their aim in the three-year joint project is to provide even more effective support to industry in the development of new and improved metallic materials. “There is a great need for such multi-scale simulation models,” states Riedel. “The component behavior of crystalline materials made of metal is just as important today in microsystems technology as it is in the automobile sector, medical technology or electrical engineering.”For further information: Prof. Dr. Hermann Riedel Phone: +49 7 61 / 51 42-1 03 hermann.riedel@iwm.fraunhofer.de Picture to download: www.fraunhofer.de/press
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