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Notes: In order to make magnesium sheets a competitive material alternative for highlysophisticated light-weight constructions the complete process chain for their production has to be investigated. In laboratory scale new alloys, casting techniques and optimized rolling and heat treatment schedules have been developed. At the Institute for Metal Forming and Metal Forming Machine Tools (IFUM) the forming capacity of magnesium sheets has been investigated. Derived from the strict quality requirements of e.g. the automotive industry, testing methods concerning mechanical properties, corrosion resistance and surface quality have been developed. It has been shown that the controlled development of a suited microstructure is the key factor for ensuring the requested product properties. Together with research and manufacturing partners the results were transferred to industrial practice and a closed loop process chain for the production of high quality magnesium sheets has been established

Notes: The investigation of the basic principles for the production of foamed out sections usingmagnesium foam for support structures by including the foaming process into the cold forming ofsections to produce indiviually locally strengthened components is the subject of this research project.To absorb tensile stress, the metal foam will be strengthened with three-dimensional branchedstruts of high-tensile materials. The quantification of the influence of locally introduced foamingelements on e.g. stiffness alterations and the influence of the resonance frequency of the total structurewill be effected by destructive but particularly also by nondestructive tests

Notes: Modern metallic materials used in high loading structures are increasingly being placedunder stringent standards with regard to the mechanical strength and deformation properties of theirindividual parts as well as with regard to the loading capacity of their junctions. In order todetermine the strain profile of the individual structural components, the mentioned topics will betaken from the SFB 675 “High tensile, locally manipulated structural components and structures”from the subproject C4 “Setting of gradient material properties and qualification of high-tension3D-NVEB weld joints”. To this end, the strengthened individual structural components will beheated with an electron beam at defined locations. This is done in order to observe the load relatedlocal micro-structure changes and consequently the targeted, structured local changes in the strengthand deformation properties of the material. A delay in the crack growth will also be sought after.Additionally, components with specifically designed tensile strength will be welded to high qualitystructures. At this the young but efficient non vacuum electron beam welding method will bepreferably developed, qualified and used because of its good welding properties regarding to animproved beam positioning, process control and weld joint defect detection

Notes: Against the background of the required weight reduction in transportation throughlightweight construction, the application of hybrid structures, where dissimilar materials are joined together, has a high technical and economical potential. In the field of sheet machining, combinations of steel and aluminium are especially interesting. In comparison to conventional steels, the application of aluminium alloys as supporting materials makes a distinct weight reduction possible. On the other hand, steels have advantages in the fields forming and welding. The application of modern high-strength steels with reduced sheet thicknesses allows weight reduction,too. But joining of material combinations of steel and aluminium is problematic. On the one hand brittle intermetallic compounds are formed between steel and aluminium. On the other hand the aluminium melt has a bad wetting behaviour. Different physical properties of both materials have to be considered, too. To achieve sufficient mechanical properties of such joinings it is necessary to limit growth of intermetallic compounds between steel and aluminium. This can be actualized by an exact energysupply. With the electron beam on atmosphere a precise and easily controllable energy supply is possible. The publication demonstrates successful investigations, which were performed with the 175 kVNVEBW (Non Vacuum Electron Beam Welding) installation at Institut of Materials Science, University of Hanover. With NVEB joining hybrid structures between zinc coated steels and 5.xxx and 6.xxx aluminium alloys were produced. In a welding-brazing process (the steel remained in the solid phase whereas the aluminium was molten) combinations with acceptable mechanical properties could be joined. By use of optimized joining parameters as well as a surface activating flux, both, a good wetting and a thin intermetallic compound 〈 10 µm were attained. Another possible strategy is a pure brazing process, for which an example is also given in the paper. The paper shows metallurgical and mechanical investigations, among other things results of elementdistribution analysis and tensile tests

Notes: In the case of welding of T-joints in a special structure, the joining is realized through atotal penetration of deck plates. For the deck plate’s thickness over 6 mm, high power MAG weldingprocess should be applied. To help experimental optimizing of this welding technology, a 3Dquasi-stationary numerical model was established to predict the penetration and weld form of the highpower MAG welding on a thick plate. In the analysis a new volumetric heat source model was putforward which considers the heat directly from the arc und that from transferred droplets separately.Because the weld pool surface under the arc was strongly pressed, the droplet heat source in the modelwas located under the workpiece surface. The size of the droplet heat source model was determinedon the base of physical principles and available experimental data. Using a commercial finite elementsoftware the weld form inclusive penetration under different welding parameters was then simulated.Through comparison with the experimental results the presented FE-model was verified

Notes: The environmentally friendly alternatives are being examined by an R&D group funded by German Federal Ministry of Education and Research. The research goals of this group are to analyze the potential of known environmental friendly gases to serve as protective atmosphere, and also to develop and to evaluate new methods for protecting the surface of magnesium melts. One possible alternative is covering the magnesium melt with CO2-snow, which is deposited on the molten bath and decreases the surface temperature of the melt. On the other hand gas expansion is the result of the sublimation of the CO2-snow which displaces any oxygen at the surface of the molten magnesium