This field of research mainly focuses on the corrosion of magnesium and aluminium alloys as well as innovative hybrid structures. The corrosion properties and mechanisms are analysed by considering the material in an integrated way from the input material and the manufacturing process to the microstructure at the nano and micron levels. The results are particularly interesting for the automotive and aerospace industries.
The susceptibility of high-strength aluminium alloys to intercrystalline corrosion still represents a great challenge in the development of these classes of materials. Intercrystalline corrosion; a form of corrosion in which the grain boundaries are preferentially dissolved and, owing to its deep penetration, can represent considerable safety risks, is considered as a potential initiator and promoter of stress corrosion cracking. On superposing the corrosive attack with mechanical stresses, SCC can lead to catastrophic component failure in high-strength aluminium alloys - in particular in Al-Mg-Zn alloys.
In the KKS (department for Corrosion and Corrosion Protection), intercrystalline corrosion and SCC are primarily investigated on precipitation-hardened wrought alloys and the corrosion mechanisms are correlated with the microstructural attributes. The grain boundary’s and matrix precipitates, the dislocation density and structure, texture, stress state and other material parameters which are specifically set by means of forming and manufacturing processes as well as by heat treating are the focus of the investigations.
As a light-weight, engineering metal, magnesium and its alloys are very important for light-weight constructions. At the same time, it is also necessary to further optimise the comparably low corrosion resistance of magnesium alloys in order to further exploit this material group’s enormous potential for light-weight constructions. The research in the department of corrosion and corrosion protection concentrates on the microstructural optimisation of material properties by identifying the corrosion mechanisms at the micron and nano scales. Here, on the one hand process-led optimising is performed by means of conventional manufacturing methods (hot-rolling, extrusion, sand, die and pressure casting) and unconventional processes (thixomoulding, continuous roll-casting, and special casting technologies) and on the other hand, by means of alloy development.
Hybrid structures and components which are composed of different materials and thus combine the individual strengths of various material systems together in order to obtain the maximum performance for minimal weight. An essential, safety relevant challenge consists of reducing the susceptibility of hybrid components to corrosion, which are dependent on the employed material combinations’ propensity to contact corrosion. By means of innovative coating systems, which can be applied either during or after the hybrid structure’s manufacture, the KKS hastens the optimisation of these new types of components for applications in modern, light-weight structures.