3D printing technology keeps the brittle tungsten crack-free
Tungsten has many excellent properties. It is resistant to corrosion and its melting point of 3,422 °C is the highest among all metals, thus making it ideal for components that work at extreme temperatures. However, there is a problem: it is very brittle at room temperature, which means it is difficult to handle using conventional techniques.
German researchers have solved this problem by using an additive manufacturing technique called electron beam melting (EBM) to solve the problem in tungsten processing. The resulting crack-free metal can be used in high-temperature components such as rocket nozzles, furnace heating elements or parts of fusion reactors and medical imaging systems.
Add material manufacture
Researchers have investigated several ways to make tungsten components using additive manufacturing, also known as 3D printing, that require little post-processing. In their latest work, they used EBM to reduce the strain of tungsten during machining, resulting in a soft material that is crack-free and easy to handle.
EBM technology uses electrons accelerated in a vacuum to melt metal powders. By moving the electron beam, 3D components can be generated from the metal in a superposition, that is, layer by layer. The technology was originally developed for titanium alloys and materials that require high processing temperatures.
Preheating reduces deformation and natural stress
To make a 3D-printed part out of tungsten, an electron beam in an EBM machine is used to warm up the tungsten metal powder before melting it. This preheating process reduces deformation and inherent stress in the metal, enabling the processing of materials that are prone to rupture at room temperature but deform at high temperatures, the researchers explain.
The new method is much better at producing crack-free tungsten than other technologies, such as laser printing. Unlike powder injection molding, another widely used advanced manufacturing technique for making complex, high-volume, clean parts, the new method "requires no expensive tools and allows the freedom to design printed parts". The long-term goal is to develop materials and processes for high-temperature applications in fusion energy and medical engineering (such as making components for CT scanners).They now plan to characterize and test the mechanical properties of printed tungsten materials for such applications.
