Hybrid compound forging is a process in which two lightweight structures are combined by the former, that is, a material knot is formed between the steel plate and the bulk metal. Moreover, different material properties can be obtained depending on the selected metal, such as connecting lightweight aluminum with high-strength steel. The Hannover Institute for Integrated Production (IPH) in cooperation with the Welding and Processing Institute (ISAF) of the Clausthal University of Technology in Germany (ISAF) is developing a new type of forging process for the manufacture of light vehicles.
The researchers' idea was to achieve a connection between the steel plate and the high-strength aluminum stud in one process step. In the past production process, it was first necessary to prepare each component separately, and then connect the two components, such as fixing the stud by welding. The original purpose of hybrid compound forging is to eliminate the subsequent connection steps and to make the production of lightweight components more efficient. In designing this new lightweight production process, the Hannover Institute for Integrated Production and the Welding and Processing Institute face two enormous challenges: As the melting point of aluminum is much lower than that of steel, the joint forming process is more complicated.
In addition, the mixing of steel and aluminum causes precipitation of a brittle phase, resulting in a reduced strength of the resulting connecting material, and is therefore unsuitable for the automotive manufacturing industry. For this reason, the researchers tried to connect the galvanized steel plate with the aluminum studs and found that zinc could firmly connect the aluminum and steel together without brittle phase.
In the "hybrid composite forging" research project, the researcher's task is to find out more suitable process conditions - that is, to determine the better temperature, pressure and speed, in order to ensure that the two parts can achieve good molding and connection. They also tried to determine whether the new process is equally applicable to different thicknesses of sheet and different types of frontal studs. Another task is to determine the carrying capacity of the connection zone and the processability of the mixing section after the connection is formed.
In the future, the hybrid forging process can be applied to the automotive and aerospace industries to produce components such as stringers, taillight brackets or cargo strapping rings. Lightweight structures play a pivotal role in the automotive and aerospace industries: Because lighter weight means lower fuel consumption.