Projects

The development of new wrought magnesium alloys, in particular sheet materials, and their utilisation in industrial applications are major goals of the research topic “Lightweight Materials” in the HGF Programme “Advanced Engineering Materials” within the research area “Key Technologies”. A major obstacle in this context is the provision of suitable feedstock materials.

Twin roll casting is an excellent method for the generation of fine grained feedstock materials that can subsequently be warm-rolled to thin sheets. The R&D work concentrates on the optimisation of the processing parameters throughout the entire processing chain and the evaluation of the resulting sheet materials. Optimisation criteria also include those connected with subsequent processing steps such as deep drawing and coatings for corrosion protection. This work is supported by materials modelling activities which allow the simulation of thermomechanical processes and the mechanical behaviour of components. Optimised alloys produced on a near industrial scale can then be made available to interested industrial partners in order to demonstrate the potential of magnesium alloy sheet material in lightweight structural applications.

Project partners:
- Faurecia Autositze GmbH
- KODA Stanz- und Biegetechnik GmbH
- Deutsches Zentrum für Luft und Raumfahrt (DLR)
- Helmholtz-Zentrum Hereon (Hereon)

Subcontractors:
- JUBO Technologies GmbH
- TWI GmbH

Project aims:
The main aim of this by the Ministry for Economic Affairs and Energy (BMWi) funded project is using lightweight constructions in order to decrease the energy consumption of vehicles and thus to conserve resources and to reduce climate-damaging emissions. The benefit of the vehicles weight reduction like reduced energy consumption is independent from the engine, which is also ecologically worthwhile for vehicles with alternative engines. The work of this project is concentrated on the weight reduction of a car seat structure using a magnesium component in the seat back. Car seats are the mechanically most loaded components in the car interior and have a significant impact on the vehicle´s weight. At the moment magnesium seat components are implemented as die cast parts for small series. The potential of weight reduction of these parts is 30 to 40 % in comparison to steel. Furthermore, wrought magnesium alloys have better mechanical properties and a better formability than cast parts. A simple substitution of steel sheets by magnesium sheets fails on the one hand on the lower strength of magnesium sheets and on the other hand on the lack of suitable joining and corrosion protection solutions. An alternative process route which combines extrusion and warm forming can be the solution to be competitive to steel components. The options in the design of extruded profiles make it possible to integrate supporting and mounting structures which are not used in conventional sheet metal applications yet. The project FUMAS opens the opportunity to bring mechanically high loaded magnesium seat components in high volume industrial application by using this new production process and the realization of new design concepts.

Project partners:
- MagIC - Magnesium Innovation Centre, MagIC, Helmholtz-Zentrum Hereon
- TEXMAT, TU-Clausthal

Project participants:
- Dr. rer. nat. Jan Bohlen, Hereon
- Dr.-Ing Sangbong Yi, Hereon
- Changwan Ha, Hereon
- Prof. Dr. rer. nat. Dr.-Ing. habil. Heinz-Günter Brokmeier , TEXMAT
- M.Sc.. Xiaohua Zhou, TEXMAT

Project aims:
The formation of microstructure and texture during a rolling process determines the properties of magnesium sheets and their technical potential for lightweight application. Weakening the texture or changing the main texture components as well as grain refinement, result in distinctly increased formability of the sheets. However, such textures lead to enhanced mechanical anisotropy.

A high number of individual mechanisms is currently discussed regarding their impact on the microstructure and texture development. Although the analysis reveals altered activation of different deformation mechanisms as well as effects on the recrystallization behavior during the rolling process, the effect of added rare earth elements or calcium in ternary magnesium alloys on these mechanisms as well as the impact on the microstructure and texture development is not well understood.

The aim of this project is to apply in-situ hard X-rays diffraction experiments using synchrotron radiation in order to draw direct conclusions about the influence of individual deformation and recrystallization mechanisms on the microstructure and texture evolution during deformation of magnesium sheet alloys.

The in-situ measurement method at the synchrotron beam allows a time-resolved description of the defect and texture development in a constant sample volume during well-defined thermo-mechanical treatments, which offers an excellent experimental basis for the analysis of the mechanisms of the microstructure changes. Concurrent to this approach micro-mechanisms are examined on a grain scale (micrometre or nanometre scale) using electron microscopy, e.g. SEM-EBSD and TEM. The influence of alloying elements, particularly rare earth elements or similar-acting elements as well as the effect of a thermo-mechanical treatment on the activation of deformation mechanisms and recrystallization is examined in a combined approach. Understanding single mechanisms and their competitive contribution on the resulting microstructure, texture development and mechanical properties allows the relative significance of such mechanisms to be derived. Furthermore, the results allow a metal physical based control of the texture development during rolling of magnesium sheets.