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from the fold-me,-print-me,-if-you-wanna-mint-me dept.
Can you 3D print Damascus steel? Pretty much, yeah
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 (DOI: 10.1038/s41586-020-2409-3) (DX)
(Score: 3, Interesting) by Anonymous Coward on Sunday June 28 2020, @12:41PM (2 children)
While Japanese blades are indeed typically folded steel, the folding is done with a single type of steel. Only after the folding is completed would the softer core have a v-shaped jacket of harder higher carbon steel (separately folded) wrapped and forge welded. This would then be drawn out to the actual blade shape. On top of that the blade gets differentially tempered (different parts cooled at different speeds, resulting in different properties in different parts of the blade), leaving you with a hard edge and a soft, springy spine and tang. The pattern along the edge ("hamon") is a result of the tempering, effectively delineating the boundary between the hardened edge steel and the softer body steel. On cheap commercial blades this is often imitated by laser etching.
In contemporary knife making, Damascus as a term is used more or less interchangeably with pattern welded steel, regardless of the far more complicated picture that exists around historical Damascus wootz.
(Score: 1, Informative) by Anonymous Coward on Sunday June 28 2020, @11:34PM (1 child)
Nit: the differential hardening process used in making a katana is not tempering [wikipedia.org]. Tempering is a (relatively low) heat treatment (normally performed after the hardening process) with a slow cooldown. Such a process is notably not done with the katana, unlike most European sword styles.
(Score: 1, Interesting) by Anonymous Coward on Monday June 29 2020, @01:50AM
You are correct. I probably should have written differentially quenched.
Having tried it so far I've only been rewarded with cracked blades. It's an odd feeling when you're holding a piece of steel as it is literally pulling itself apart...