Reforming materials under extreme pressure

Steinbeis experts develop high-performance reforming process

Weight reduction is a key challenge in the metal processing industry, since it is central to reducing energy consumption. As a result of light construction requirements and the drive to minimize energy consumption – especially in the automotive industry – experts are constantly examining the properties and processing techniques of light construction materials. In recent years, magnesium-based materials and magnesium alloys have become particularly interesting as important construction materials. The reason magnesium has become such a popular material for reducing weight: its specific properties. It has a low density, offers excellent thermal conductivity and it is strong. What is needed however, is the innovative manufacturing technology to produce the specific magnesium components that are required – without cracks, and in the right quality for industrial applications. This is where Steinbeis research comes in, currently being carried out in Dresden by the Innovation Center for Intelligent Functional Materials, Welding and Joining Techniques, Implementation.

For the research project, the Steinbeis experts have established a technological procedure for developing a high-performance thermo gas-kinetic reforming process. The aim of the process is to produce magnesium component structures with high reformation levels (formability).

To simulate certain parts of the thermo gas-kinetic process when heating, bending or deep-drawing the high-strength, high-ductility magnesium alloy called AZ31, the Steinbeis experts first created a viscoelastic FE model. This model was used to examine and analyze the influence of integrated sub-processes on the reforming process – from the preheating process (23-350°C) to the use of process-inert gases, the use of lubricants on magnesium sheets of different thicknesses, and tool design (radii). Finally, the project team investigated plastic deformations as well as principal, secondary and comparative stress according to predefined process parameters. Based on their investigations, it was possible to optimize the reforming process. In addition, the experts at the Dresden-based Innovation Center conducted experiments on the influence of the new process parameters on the reforming process. These were pertinent to the heating of metal sheets and tools, the use of an inert gas (Argon), the application of conventional lubricants (Beruforge 120D, Berulit 935 and 393G) and the nano-graphite traction protection that is dispersed when adjusting tool radii and magnesium sheet thicknesses.

The identified process window could be used to produce crack-free, faultless magnesium component structures according to defined forming contours with high levels of formability. The results of thermobending based on the newly integrated process parameters will now be transferred to simulations and experimentation with the deepdrawing process used to produce finished magnesium parts, possibly with adaptations.

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