Development of new strategies for the mechanical joining of components made of aluminum die casting

Structures made of aluminum die casting are being used in increasing quantities as well as component sizes for various applications. Due to the size of the components, heat treatment of the cast parts following the casting process is omitted in order to meet dimensional accuracy requirements and reduce production costs. From such an approach, challenges arise with regard to the mechanical joining of these aluminum die-cast structures. On one hand, the absence of heat treatment results in a general decrease in ductility. On the other hand, the increasing size of the components introduces process-related tolerances regarding the quality of the casting, including the presence of air or gas inclusions, and significant variations in ductility within the component. These factors present challenges for mechanical joining technologies, such as the potential risk of crack-related defects during the joining process. For the robust mechanical joining of such materials, the development and validation of suitable joining strategies for aluminum die cast components is presented in this paper. A preparatory step involving localized heat treatment in the joining area is implemented to enhance the suitability of the casting material for mechanical joining. The objective is to generate an improved ductility state in the aluminum die casting material, enabling crack-free joining through self-pierce riveting. Additionally, the formability of the aluminum die casting material is characterized using a specially developed ductility testing method. This allows the prediction of potential crack-related defects during mechanical joining. The methods described are developed using the AlSi10MnMg material in its as-cast state and applied to the self-pierce riveting process.