Electron beam melting brings brittle metal into shape

For the first time, KIT researchers have succeeded in producing components made of tungsten for use in the high-temperature range in the 3D printing process of electron beam melting.

Component made of tungsten, manufactured in 3D printing using the electron beam melting process (Photo: Markus Breig, KIT)

Component made of tungsten, manufactured in 3D printing using the electron beam melting process (Photo: Markus Breig, KIT)

At 3,422 degrees Celsius, tungsten has the highest melting point of all metals. Ideal for use where it gets really hot, for example for space rocket nozzles, heating elements in high-temperature furnaces or in fusion reactors. At the same time, however, the metal is very brittle and therefore difficult to process. Researchers at the Karlsruhe Institute of Technology (KIT) have now found an innovative approach for "making the brittle pliable": They developed new process parameters for the electron beam melting process so that tungsten can also be processed.

The metal tungsten has properties that make it very attractive as a material: it is very corrosion-resistant, heavy as gold, as tungsten carbide as hard as diamond, and at 3,422 degrees Celsius it has the highest melting point of all metals. However, this metal is very brittle at room temperature. Due to its properties, tungsten is difficult to process using conventional manufacturing methods. Processing is very costly and time-consuming in the manufacturing process. An alternative is 3D printing, with which components can be manufactured in such a way that they hardly need any further processing. "We are currently working on the additive manufacturing of components from the high-melting metal tungsten using the electron beam melting process, or EBM for short, also known as electron beam melting," explains Dr. Steffen Antusch from the Institute for Applied Materials - Materials Science (IAM-WK) at KIT. The research team was able to successfully adapt the EBM process for tungsten. The specially developed process parameters now allow the 3D printing of components made of tungsten. “The areas of application for this metal are impressively diverse. Due to its special properties, it is ideally suited for high-temperature applications in energy and lighting technology as well as for space travel and medical technology and is therefore indispensable for the modern high-tech industry, ”says Alexander Klein from the IAM-WK. “The areas of application for this metal are impressively diverse. Due to its special properties, it is ideally suited for high-temperature applications in energy and lighting technology as well as for space travel and medical technology and is therefore indispensable for the modern high-tech industry, ”says Alexander Klein from the IAM-WK. “The areas of application for this metal are impressively diverse. Due to its special properties, it is ideally suited for high-temperature applications in energy and lighting technology as well as for space travel and medical technology and is therefore indispensable for the modern high-tech industry, ”says Alexander Klein from the IAM-WK.

Preheating allows processing of brittle materials

EBM is an additive manufacturing process in which the electrons accelerated under vacuum selectively melt metal powder and thus create a 3D component layer by layer, i.e. additively. The main advantage of this process is the energy source used, the electron beam. This enables the metal powder and the carrier plate to be preheated before melting and thus reduces deformations and internal stresses. This allows the processing of materials that break easily at room temperature and are deformable at high temperatures. However, the materials used must be electrically conductive. The process is therefore out of the question for ceramic materials, since the EBM process is based on the principle of electrical charge. Preheating the metal powder before melting it reduces deformation.

Lightweight components made of titanium for KA-RaceIng

The EBM process was originally developed to process titanium alloys and materials that require elevated process temperatures. So far, lightweight components made of titanium have been produced in the KIT technology house, for example for the KIT Formula Student project KA-RaceIng.

In the research programs of the Helmholtz Association and the European fusion program EUROfusion, the IAM-WK researches materials and processes in order to be able to manufacture high-temperature materials for future applications, for example in fusion energy or in medical technology.

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