Next step 3D printing moves into the "fourth dimension"

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A newly established department at TU Berlin researches materials for additive manufacturing...

Although 3D printing has been used for over 30 years, this type of component manufacturing is still relatively young compared to established production processes. Especially with raw materials—particularly when it comes to metallic materials—there is still room for optimization. However, with the help of 3D printing, products with previously impossible complex material compositions and thus completely new properties can be manufactured. This is precisely the point where the newly established field of "Materials for Additive Manufacturing" by Prof. Dr.-Ing. Christian Haase aims to make an impact.

Additive manufacturing follows the bottom-up principle

Glowing hot steel flows into a mold and, after solidifying, is still glowing when rolled into sheets or rods. These can then be deep-drawn, bent, or forged into different shapes. However, with each of these transformations, the material structure changes, although the most important material properties are already determined during the casting of the raw material, says Haase. In contrast to this top-down approach, additive manufacturing uses a bottom-up method. In 3D printing, the finished product—aside from post-processing work such as polishing—is created in a single step. In the powder bed process, a laser or electron beam selectively melts the material powder at specific points, allowing a complex workpiece with almost any shape to be built layer by layer. In "laser deposition welding," even entirely different materials can be combined into a single workpiece, with the desired material being sprayed on just before melting by the laser (e.g., as a powder-gas mixture).

Researchers influence the material in laser metal deposition

This production method allows for different material and surface properties to be set at various points of the workpiece directly during shaping—and at completely different scales, explains Haase. Besides the ability to combine different materials in laser deposition welding, the energy, beam diameter, and movement speed of the laser are parameters that can influence material properties. From the differing chemical compositions and arrangements of individual atoms, to larger-scale desired variations in the crystal structure, all the way to the grain structure of the material, which is sometimes visible to the naked eye, researchers can make targeted changes.