Innovative joining technology for multi-material applications with high manganese steels in lightweight car body structures

Due to restrictions imposed by legal requirements, automotive manufacturers are forced to reduce the pollutants emission of new models. A promising approach is the reduction of the vehicle weight, whereby the body in white offers great potential. This weight reduction is realized by new car body constructions, which contain the increasing usage of different materials. Furthermore, new lightweight materials like TWIP steels become more important. The successful and economic implementation of multi-material design with TWIP steels requires the availability of suitable joining technologies. Conventional thermal joining technologies can be used in consideration of specific characteristics related to welding austenitic steels. Within the project, challenging material combinations related to dissimilar materials are investigated. In this paper, high-speed joining is investigated as an innovative and promising joining technology for multi-material applications. This mechanical joining technology contains an auxiliary joining part, called tack, which is driven with high speed into the joining partners. The challenges as well as the optimization of the auxiliary joining part is shown. The investigations are attended by metallographic analysis, whereby mechanical properties are determined through destructive tests. The characteristics are compared to the results of current used standard tacks.