Browsing by Author "Schaper, Mirko"

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    Influence of Solidification Rates and Heat Treatment on the Mechanical Performance and Joinability of the Cast Aluminium Alloy Alsi10mg
    (German Academic Society for Production Engineering (WGP), 2022) Neuser, M.; Grydin, O.; Frolov, Yaroslav; Schaper, Mirko
    ENG: In modern vehicle chassis, multi-material design is implemented to apply the appropriate material for each functionality. In spaceframe technology, both sheet metal and continuous cast are joined to castings at the nodal points of the chassis. Since resistance spot welding is not an option when different materials are joined, research is focusing on mechanical joining methods for multi-material designs. To reduce weight and achieve the required strength, hardenable cast aluminium alloys of the AlSi-system are widely used. Thus, 85–90% of aluminium castings in the automotive industry are comprised of the AlSi-system. Due to the limited weldability, mechanical joining is a suitable process. For this application, various optimisation strategies are required to produce a crack-free joint, as the brittle character of the AlSi alloy poses a challenge. Thus, adapted castings with appropriate ductility are needed. Hence, in this study, the age-hardenable cast aluminium alloy AlSi10Mg is investigated regarding the correlation of the different thicknesses, the microstructural characteristics as well as the resulting mechanical properties. A variation of the thicknesses leads to different solidification rates, which in turn affect the microstructure formation and are decisive for the mechanical properties of the casting as well as the joinability. For the investigation, plates with thicknesses from 2.0 to 4.0 mm, each differing by 0.5 mm, are produced via sand casting. Hence, the overall aim is to evaluate the joinability of AlSi10Mg and derive conclusions concerning the microstructure and mechanical properties.
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    Laser Beam Melting of Functionally Graded Materials with Application-Adapted Tailoring of Magnetic and Mechanical Performance
    (Elsevier, 2021) Andreiev, Anatolii; Hoyer, Kay-Peter; Dula, Dimitri; Hengsbach, Florian; Grydin, Olexandr; Frolov, Yaroslav; Schaper, Mirko
    ENG: The processing of functionally graded materials (FGMs) using laser beam melting (LBM) is a promising technique for increasing the efficiency of conventional machine components, especially for e-mobility. Therefore, the aim of the current study is to prove the manufacturability of tailored mechanical and magnetic properties in a rotor for an electric motor. For this purpose, the design of additively manufactured rotors with application-adapted tailoring of the properties in the same component using FGM was proposed. The first step was to investigate whether the FGM of the components, i.e. soft-magnetic steel for the rotor core and high-strength steel for the rotor shaft ends, are suitable for machining by LBM. Subsequently, multi-material samples of the two investigated steel types with their different arrangement were processed by LBM. Furthermore, post-processing heat treatments and their effects on the microstructure and resulting magnetic properties as well as the mechanical performance of mono- and multi-material samples were analyzed. The combination of LBM and an additional post heat treatment enables both the formation of a good adhesive bond between the two alloys and the desired tailoring of the properties in the FGMs investigated.