The development of novel structural materials with increasing mechanical requirements is a very resource-intense process if conventional methods are used. While there are high-throughput methods for the development of functional materials, this is not the case for structural materials. Their mechanical properties are determined by their microstructure, so that increased sample volumes are needed. Furthermore, new short-time characterization techniques are required for individual samples which do not necessarily measure the desired material properties, but descriptors which can later be mapped on material properties. While universal micro-hardness testing is being commonly used, it is limited in its capability to measure sample volumes which contain a characteristic microstructure. We propose to use alternative and fast deformation techniques for spherical micro-samples in combination with classical characterization techniques such as XRD, DSC or micro magnetic methods, which deliver descriptors for the microstructural state.

Electromagnetic forming (EMF) is a high-speed forming process that is already established in the macroworld. Due to its advantages like high deformation rate and cheaper tools, it is introduced to microforming. In this research, the replication of prismatic optical microstructures is investigated. EN AW-1050A (Al99.5) micrometal sheets with a thickness of 50 μm and 300 μm are electromagnetically micro-embossed. With this technique, it is possible to successfully replicate triangular cross section micro V-grooves of 86.6 μm in width and 24.1 μm in depth with an average surface roughness of Sa = 44 nm. The microstructures of the embossing tool are generated by diamond micro chiseling (DMC), a novel machining process to produce microstructures with discontinuous geometry, like miniature cube corner retro reflectors and V-grooves with well-defined endings.

In electromagnetic forming of thin sheet metal, the die is located within the effective range of the electromagnetic wave. Correspondingly, a current is induced not only in the sheet metal, but also in the die. Like the current in the workpiece, also the current in the die interacts with the electromagnetic wave, resulting in Lorentz forces and changes of the electromagnetic field. With the aim to study the influence of different electromagnetic die properties in terms of specific electric resistance and relative magnetic permeability, electromagnetic simulations were carried out. A change in the resulting forming forces in the sheet metals was determined. To confirm the simulation results, electromagnetic forming and embossing tests were carried out with the corresponding die materials. The results from simulation and experiment were in good agreement.

Electrohydraulic forming is a working media based high speed technique that is usually applied for sheet metal processing. In this process a shock wave acts as a flexible punch that transmits the punching force in a very short period of time. This force is usually used to accelerate the workpiece towards the passive tool. In Contrast to sheet forming, the electrohydraulic method is still not adapted to bulk forming. Although, the exchange of a mechanical rigid punch by a shockwave with a flexible shape enables special advantages especially if parts with millimeter dimensions or smaller are to be processed. But in case of deep and small cavities with a high aspect ratio are to be filled, the forming energy is not transferable within one shock wave. To overcome these obstacles the incremental electrohydraulic forming is introduced. As an example, the electrohydraulic extrusion of cylindrical samples (aluminum Al99.5) with an initial diameter of 1.5 mm was performed with a series of consecutive shock waves.

With impulse forming technologies like electrohydraulic and electromagnetic forming, the punch in a stamping process is replaced by an impulse that acts in a short period and provides high strain rates of over 1000 s^-1. Beneath the advantages which are accompanied with high speed forming the used dies and tools have to withstand mainly dynamic loads. This enables the realization of new concepts to increase flexibility in tooling for impulse forming. The flexibility covers different aspects like intrinsic geometrical adaptability of the punch, reduced demand for mechanical stiffness, rapid manufacturing of the dies due to the usability of alternative tool materials, modular dies and the opportunity of consecutive or parallel process combinations. These aspects of flexible tooling are illustrated by examples in different size scales for sheet metal, tube and bulk forming. The proposed techniques allow cold forming of small series or even single parts more cost and time efficiently.

Conventional testing procedures for characterizing the mechanical behavior of materials require intense preparation in geometry and in the handling of the samples to apply specific stress conditions. Furthermore, these procedures are time consuming. In a novel method for high-throughput development of new material, spherical and cylindrical micro samples should also be tested within a short time. For mechanical testing, the samples need to be exposed to specific types of stress. As most conventional testing procedures are not applicable, new testing procedures are demanded. The incremental electrohydraulic extrusion of micro samples through micro channels is a new testing procedure that was introduced for short-term material characterization. Loading energy is used to cause shock waves that incrementally push the samples through the forming die. The resulting deformation progress is measured between the forming steps. In this research, process simulations are used for channel design and material flow analysis. The designed channels that cause specific stress in samples are realized by stacking elements radially or axially. The stacking enables sample access for measurement and unloading and ensures good machinability of the forming channels. New testing cases for short-term characterization of cylindrical as well as spherical micro samples by electrohydraulic extrusion are presented according to monotone tensile, compression, and torsion testing. Furthermore, production-related testing and cyclic load testing are introduced by incremental electrohydraulic extrusion. By measuring the deformation due to the dependence on supplied energy, flow curve equivalents are determined that correspond to values from conventional material testing procedures.