Magnesium New Processes Make Magnesium Suitable for Industrial Use

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After three years of research, a team from TU Bergakademie Freiberg (Germany) has developed an end-to-end process chain for lightweight magnesium components together with industrial partners. The result is magnesium components that are around a third lighter than common aluminum solutions while retaining comparable strength.

It is lighter than aluminum. Despite this, magnesium has hardly been used by industry to date, as its processing into components is considered complex and energy-intensive. In the Clean-Mag research project, a team from various departments at TU Bergakademie Freiberg worked together with industrial partners to develop an end-to-end process chain for lightweight magnesium components—from the melt to the functional prototype. "Our aim was to make magnesium usable as an industrial lightweight material through new, shorter manufacturing processes," says Professor Ulrich Prahl from the Institute of Metal Forming at TU Bergakademie Freiberg, Germany. 
Starting with sheet metal production, the team at the Institute of Metal Forming at TU Bergakademie Freiberg relies on innovative processes: "The casting rollers used already enable the production of magnesium sheets with thicknesses of around 0.2 inches. This means that downstream forming steps can be reduced." The result is magnesium components that are around a third lighter than common aluminum solutions while retaining comparable strength. Among other things, the research alliance has produced lightweight magnesium computer housings, rail seat backs for high-speed trains such as the TGV, hinge parts for transport containers and an airflow channel for a hovercraft rescue vehicle.

Converting the melting and heating processes to hydrogen and making them more energy-efficient is a key step towards producing magnesium in a climate-neutral and more cost-effective way.

Professor Hartmut Krause from the Chair of Gas and Thermal Engineering at TU Bergakademie Freiberg

Three Building Blocks for More Climate-Friendly Magnesium Processing

As the first component of the new manufacturing process, the researchers developed technologies that can replace fossil fuels with up to one hundred percent climate-neutral hydrogen. "Converting the melting and heating processes to hydrogen and making them more energy-efficient is a key step towards producing magnesium in a climate-neutral and more cost-effective way," says Professor Hartmut Krause from the Chair of Gas and Thermal Engineering at TU Bergakademie Freiberg, "digital twins help us to better understand the processes and, above all, to improve them during operation."
A second lever lies in the significantly shortened process route. The team relies on the casting-rolling process integrated at the Institute of Metal Forming for the rapid conversion of the liquid magnesium melt into a preliminary product. The heat from the casting heat is used directly for forming, resulting in sheets or wires that already have almost the desired component shape. Energy and time-consuming downstream process steps can thus be reduced.

For wire production, the research team also developed the GieWaCon process, which combines wire casting rolling with the Conform process. The latter is already established for materials such as copper and was applied to magnesium for the first time in the project. As the Conform process works at room temperature, the heat present in the casting process can be used to directly manufacture a wire product in just a few process steps. The magnesium wires produced in the project achieved a final diameter of 0.06 inches—either directly using the conform process or by subsequent wire drawing. Furthermore, the project shows that the principle of the shortened process route can also be transferred to other forming processes. For example, the magnesium alloy used was successfully forged; the resulting components were reworked immediately after forming, for example by deburring or milling. In addition, an industrial partner developed an extrusion process in which billets are first cast and then extruded from the casting heat. The resulting tube is cut and bent open so that workable sheets can be produced—also without additional heating steps.

Calcium-Containing Magnesium Alloy Used

The third component used is the calcium-containing magnesium alloy ZAX210. It can be processed well even at comparatively low forming temperatures of around 400 °F and still guarantees stable mechanical properties. "The magnesium alloy allows us to carry out forming processes at significantly lower temperatures without compromising on the component properties," explains Professor Ulrich Prahl. In addition, suitable surface coatings were examined for all prototypes in order to ensure corrosion resistance and usability of the magnesium components under real conditions. In addition, the project team analyzed and optimized various welding processes, which were specifically adapted to the magnesium alloy used and further developed for the respective demonstrators. Together with the industrial partners from the project, the team intends to continue advancing the developed manufacturing routes in the future and apply them to other components and shaping processes. A CO₂ calculator, which companies can use to compile and compare possible process chains for the forming of magnesium, has been developed specifically for this purpose within the project.

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