Multi-material bulk metal components allow for a resource efficient and functionally structured component design, with a load adaptation achieved in certain functional areas by using similar and dissimilar material combinations. One possibility for the production of hybrid bulk metal components is Tailored Forming, in which pre-joined semi-finished products are hot-formed using novel process chains. By means of Tailored Forming, the properties of the joining zone are geometrically and thermomechanically influenced during the forming process. Based on this motivation, forming processes (die forging, impact extrusion) coupled with adapted inductive heating strategies were designed using numerical simulations and successfully realised in the following work in order to produce demonstrator components with serial or coaxial material arrangements. The quality of the joining zone was investigated through metallographic and SEM imaging, tensile tests and life cycle tests. By selecting suitable materials, it was possible to achieve weight savings of 22% for a pinion shaft and up to 40% for a bearing bush in the material combination of steel and aluminium with sufficient strength for the respective application. It was shown that the intermetallic phases formed after friction welding barely grow during the forming process. By adjusting the heat treatment of the aluminium, the growth of the IMP can also be reduced in this process step. Furthermore, for steel-steel components alloy savings of up to 51% with regard to chromium could be achieved when using low-alloy steel as a substitute for high-alloy steel parts in less loaded sections. The welded microstructure of a cladded bearing washer could be transformed into a homogeneous fine-grained microstructure by forming. The lifetime of tailored formed washers nearly reached those of high-alloyed mono-material components.

In order to promote aluminum scrap recycling and reduce remelting losses, solid-state recycling processes are subject to increasing academic attention. These processes range from severe plastic deformation (SPD) to diffusion-based processes like field-assisted sintering (FAST). In this study, a FAST-based recycling route consisting of precompaction, FAST, and impact extrusion of dry machined EN AW-6082 and EN AW-7075 aluminum chips was used to create multi-material parts from different aluminum alloys. To examine the effect on the resulting part quality, two different hybrid material layouts were created during cold compaction of the chips. The subsequent sintering process took place in a field-assisted sintering (FAST) machine at 400°C and 500°C for a duration of 5 min under a pressure of 85 MPa, allowing for the analysis of inter-chip diffusion. These sintered blanks were then cold-formed by impact extrusion. Metallographic and computed tomography analyses as well as hardness measurements were performed for property evaluation before and after heat-treatment.

Due to the high specific surface area of titanium aluminide powders, significant and unavoidable surface oxidation takes place during processing. The resulting oxides disrupt the conventional powder metallurgical process route (pressing and sintering) by reducing the green strength and sintered properties. Oxide-free particle surfaces offer the potential to significantly increase particle bond strength and enable the processing of difficult-to-press material powders. In this work, the effect of milling titanium aluminide powder in a silane-doped atmosphere on the component properties after pressing and the subsequent sintering was investigated. Ball milling was used to break up the oxide layers and create bare metal surfaces on the particles. With the help of silane-doped inert gas, the oxygen partial pressure was greatly reduced during processing. It was investigated whether oxide-free surfaces could be produced and maintained by milling in silane-doped atmospheres. Furthermore, the resulting material properties after pressing and sintering were analysed using density measurements, hardness tests, EDX measurements, and micrographs. It was concluded that ball milling in a silane-doped atmosphere produces and maintains oxide-free particle surfaces. These oxide-free surfaces and smaller particle sizes improve the component properties after pressing and sintering.

Regarding tool wear and energy consumption when forging steel parts, tailored preform geometries are beneficial. In particular, the number of forging steps can be reduced, in comparison to conventionally rolled cylindrical stock material, if preformed billets are used. In order to assess the potential offered by cast preforms as semi-finished products for a subsequent forging process, cylindrical steel billets (G42CrMo4) were cast by sand casting and then upset with different degrees of deformation φ (0.7-1.5), forging temperature (600-1200 °C) and ram speed (30-700 mm/s). Forging of conventional rolled bar material under the same forming conditions was used as a reference. After forming, the specimens were heat treated and the mechanical properties were determined by tensile tests (DIN EN ISO 6892-1) and notch impact tests (similar to DIN EN ISO 148-1). The microstructures were examined by metallographic analysis. For the investigated process variables, no significant influences on the tensile strengths or impact energies of the cast and forged specimens were found. While the tensile strengths of the cast and forged specimens meet the values of conventionally rolled and forged specimens, the impact energies of the cast and forged specimens surpass those of the reference. This is attributed to compressed pores, which were incompletely closed during forging. A criterion for the design of a die forging process of cast preforms will be derived based on the obtained results.