Can you 3D print Damascus steel? Pretty much, yeah [arstechnica.com]
Damascus steel—and modern versions of the steelmaking technique—is generally synonymous with artisan forgework. In traditional Japanese sword-making, for example, the steel is repeatedly folded to produce hundreds or thousands of alternating layers, producing intricate patterns in the finished product. That's not just for the visual effect—the layers alternate between hard-but-brittle and more flexible steel, combining for the best of both worlds.
A new study led by Philipp Kürnsteiner of the Max Planck Institute for Iron Research shows that it is possible to do something very similar with laser additive manufacturing—3D printed metals.
Traditional folded steels combined two steels that varied by carbon content and in their microscale structure, which is controlled by how quickly it cools (by quenching). In this case, the researchers were using a nickel-titanium-iron alloy steel that works well with these 3D printing techniques, in which metal powder is fed onto the work surface and heated with a laser.
[...] The team's idea was to use the layer-by-layer printing process to manipulate the temperatures each layer experienced, alternating softer, more flexible layers with layers hardened by that precipitation process. While printing a cubic chunk of steel, they did this simply by turning the laser off for a couple minutes or so every few layers. The top layer would rapidly cool, converting to the desired crystalline form. Then, as additional layers were added on top, temperatures in the crystalline layer would cycle back up, inducing the precipitation of the nickel-titanium particles.
High-strength Damascus steel by additive manufacturing [nature.com] (DOI: 10.1038/s41586-020-2409-3) (DX [doi.org])