Treatments of steel sheets for the high pressure die casting of aluminum/steel sheet-metal hybrids with low gap and distortion formation (BeST)

• Applicants: Professorin Dr.-Ing. Kirsten Bobzin; Professor Dr.-Ing. Andreas Bührig-Polaczek; Professor Dr.-Ing. Gerhard Hirt
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing ; Coating and Surface Technology ; Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: from 2014 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 245566034

In the first project it could be shown that geometrically simple, hybrid Al-cast/steel joints can be produced locally by coating and structuring of the insert in a material-, force- or form-fit manner in high-pressure die casting, depending on the process and material conditions. The second phase focuses on the WING tool as a geometrically more complex hybrid tool. This allows the scientific investigation of relevant parameters and mechanisms of the individual process steps and their interactions at the required level of complexity. Therefore, the overall goal of the planned project is on the one hand the exp. development of the relevant mechanisms and their dependencies on process and material parameters along the production chain. On the other hand, a modular overall model is to be developed in which the modelling of individual process steps is included as well as criterion functions created on the basis of the experiments and the database of material and process data. The criterion functions define the correlation of e.g. individual process parameters and the type of structuring with the achieved composite properties on a statistically secured basis. In sum, the experimental work and the development of a modular overall model should lead to an understanding of the basic mechanisms of hybrid sheet metal/cast composites in die casting, even for complex requirements, and thus enable their process-reliable production. The convex and concave design of the WING tool and the perforations in the substrate force the melt to be deflected, which on the one hand causes the casting to shrink onto and off the sheet metal and on the other results in complex, location-dependent flow conditions. The structures and coatings used can also influence the local topography and element concentration and thus affect wetting, flow and solidification. Systematic in situ measurements are used to check and evaluate simulations in order to enable process-dependent design of the local surface pretreatment. Furthermore, the composite quality is to be correlated with the local process variables and specific criterion functions for predicting the composite quality are to be established. With the help of these criterion functions in combination with thermophysical simulations, e.g. areas of the substrate that are suitable for structuring and/or those areas in which a coating is more likely to enable the optimum bond between aluminium casting and steel are to be determined. These investigations complement the knowledge gained in the first project on composite production on a two-dimensional level and allow the transferability of the previous experimental and simulative work to components of any complexity.

• DFG Programme: Research Grants