High-strength aluminum alloys have a great lightweight potential due to their high specific strength-to-weight ratio. However, industrial use of this material is limited due to the low formability at room temperature. In recent years, the so-called hot forming quench (HFQ®) process has proven, to be an effective forming method for manufacturing high-strength aluminum alloys. During deep drawing, the high cooling rate generates the potential for a subsequent aging operation and thereby the formation of strength-increasing precipitations. As a result, complex-shaped components with high strength can be produced. In the future, tailored components with both ductile and high-strength areas are increasingly needed to fulfill the growing lightweight and safety requirements of the government. One method to influence the mechanical properties is the use of a tailor quench forming (TQF) process. In this regard, a simultaneous component production and adjustment of the final mechanical properties is possible. However, it has not been investigated so far, how the tool temperature and the subsequent aging parameters influence the thermal interactions and thus the mechanical characteristics of the parts. In addition, the crash performance of these components has not been investigated. For this reason, a high-strength aluminum alloy is quenched under different thermal conditions and is then artificially aged. To determine the resulting thermo-mechanical properties, temperature analysis, hardness tests and tensile tests, as well as high-speed tests have been performed.
In conjunction with mechanical joining processes. Mechanical joining processes play a key role for the realization of multi-material lightweight structures, which are essential with regard to environmental protection. However, joining of dissimilar high-strength materials is challenging due to the varying properties of the joining partners and due to their high flow stresses and often limited ductility. Thus, the evolution of established processes as well as the development of innovative and highly productive joining technologies are necessary. Requirements for a highly volatile production environment are versatility, flexibility, resilience and robustness. Within this contribution, current trends and innovations related to selected mechanical joining processes for enabling the material mix are outlined in order to point out opportunities to address these requirements in the future. In this context, joining using cold formed pin structures is presented as a promising approach for connecting dissimilar materials like metals to fibre-reinforced plastics. Furthermore, it is shown how the shear-clinching technology can be combined with a process-adapted application of locally limited heat treatment in order to promote the joinability and control the material flow during joining. A novel approach for reducing process forces and expanding process windows is the use of ultrasonic assistance for mechanical joining operations, which is demonstrated by the example of a nut staking process with superimposed high frequency oscillation. As concerns the widely used self-piercing riveting technique, current research activities relate not only to the further development of the joining process itself, for example by combining self-piercing riveting and tumbling, but also to the use of new rivet materials like high strain hardening stainless steels. In addition, the evolution towards mechanical joining 4.0 against the background of data-based process control in conjunction with of mechanical joining processes is also subject of the considerations.
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