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posted by chromas on Sunday June 28 2020, @07:47AM   Printer-friendly
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)


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  • (Score: 5, Informative) by aristarchus on Sunday June 28 2020, @08:09AM (13 children)

    by aristarchus (2645) on Sunday June 28 2020, @08:09AM (#1013604) Journal

    Sorry to burst everyone's bubble, but this is not Damascus Steel. It is a facsimile of "pattern welded steel", which is indeed what Japanese swordsmiths used to produce some of the greatest blades. But Damascus is a different fish, and it may have been a crucible steel with naturally occurring alloys, which did produce a pattern on finished blades, but the source and technique are very different. So let's not get all 3-D printing about a metallurgical technology that is not understood to begin with. I could go on, as I have extensive experience with steel, and iron, but mostly irony.
    Signed,
    Aristarchus of Samos

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  • (Score: 3, Interesting) by pvanhoof on Sunday June 28 2020, @08:44AM (5 children)

    by pvanhoof (4638) on Sunday June 28 2020, @08:44AM (#1013608) Homepage

    The Damascus-like sample was significantly stronger, holding up to about 20 percent more stretching force. It didn’t reach the strength of a typical, traditionally made maraging steel, but the researchers note that this requires “a time-consuming and costly post-process ageing heat treatment.”

    So yes, this is not the same steel.

    • (Score: 2) by takyon on Sunday June 28 2020, @09:49AM (4 children)

      by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Sunday June 28 2020, @09:49AM (#1013615) Journal

      Inspired by ancient Damascus steels—which have hard and soft layers, originally introduced via the folding and forging techniques of skilled blacksmiths—we produced a material consisting of alternating soft and hard layers. Our material has a tensile strength of 1,300 megapascals and 10 per cent elongation, showing superior mechanical properties to those of ancient Damascus steel.

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      • (Score: 2, Informative) by Anonymous Coward on Sunday June 28 2020, @12:09PM (2 children)

        by Anonymous Coward on Sunday June 28 2020, @12:09PM (#1013631)

        > 1,300 megapascals
        Sorry, I grew up with US Customary units, this is nearly 190,000 psi steel, which sounds similar to common steel alloy 4340. See for example, Table 4 at https://www.astmsteel.com/product/4340-steel-aisi/ [astmsteel.com]
        Condition Y (heat treatment) which quotes ultimate tensile of 1230-1380 mPa at an elongation of 10%.

        Many modern steels exceed these properties, maraging steels by a factor of 2 or 3. The ancients did well for a craft operation, but can't match the results of large scale military/industrial development.

        • (Score: 2) by HiThere on Sunday June 28 2020, @03:08PM (1 child)

          by HiThere (866) Subscriber Badge on Sunday June 28 2020, @03:08PM (#1013686) Journal

          The idea of Damascus (and Japanese sword) steel was a combination of hardness and toughness. You can't measure that with a simple pressure test. (I'm not saying modern steels wouldn't be better, as I don't know. Merely that the proof you cite is inconclusive.)

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          • (Score: 1, Informative) by Anonymous Coward on Monday June 29 2020, @02:28AM

            by Anonymous Coward on Monday June 29 2020, @02:28AM (#1013953)

            > a combination of hardness and toughness.

            That is why I included two metrics in my post about 4340
            > ultimate tensile of 1230-1380 mPa at an elongation of 10%.

            The elongation number relates to toughness, 0% elongation == glass, fractures without stretching.

            By carefully controlling the heat treat process it is common to get a range of properties in one piece of steel--harder here, tougher there. For example, induction heating of specific zones of a part are possible. This is used for highly stressed gear teeth (F1 gearboxes)--hard on the wearing faces but tough at the root of the teeth.

      • (Score: 2) by aristarchus on Monday June 29 2020, @12:28AM

        by aristarchus (2645) on Monday June 29 2020, @12:28AM (#1013905) Journal

        This is the part that is just plain wrong. Damascus steel was not made by layering, and forge-welding and folding. Ignorance like this in an article allegedly dealing with steel metallurgy is not confidence inspiring. Of course, common usage has called pattern-welded steel "damascus" for quite some time, which begs the question.

  • (Score: 2) by inertnet on Sunday June 28 2020, @12:24PM

    by inertnet (4071) on Sunday June 28 2020, @12:24PM (#1013633) Journal

    Also Damascus is 9000 km from Tokyo, based on that alone it's highly unlikely that the Japanese got their steel from Damascus.

  • (Score: 3, Interesting) by Anonymous Coward on Sunday June 28 2020, @12:41PM (2 children)

    by Anonymous Coward on Sunday June 28 2020, @12:41PM (#1013638)

    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)

      by Anonymous Coward on Sunday June 28 2020, @11:34PM (#1013888)

      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)

      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

        by Anonymous Coward on Monday June 29 2020, @01:50AM (#1013936)

        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...

  • (Score: 1, Informative) by Anonymous Coward on Sunday June 28 2020, @04:58PM

    by Anonymous Coward on Sunday June 28 2020, @04:58PM (#1013726)

    "Damascus steel" is not from Damascus. It's from India, just like "Arabic numerals" are actually Indian numerals.

  • (Score: 2) by sjames on Monday June 29 2020, @02:03AM

    by sjames (2882) on Monday June 29 2020, @02:03AM (#1013940) Journal

    Yes, there have been many theories advanced about how they managed to get the steel to spontaneously arrange itself into a layered pattern, from serious theories to armchair guesses by people who have never forged anything and have no idea how. None have proven out. Some even theorize that it was in fact folded and the rest is just obfuscation to maintain a market advantage.

    Many modern offerings casually use the term "Damascus steel" when it's really folded or otherwise pattern welded. That bit of marketing puffery has been so overused that many think that IS Damascus steel.

    A better term would be Damascus-like. One thing we can be fairly sure of, they probably didn't use laser sintering in Damascus.

  • (Score: 0) by Anonymous Coward on Monday June 29 2020, @08:15PM

    by Anonymous Coward on Monday June 29 2020, @08:15PM (#1014235)

    This is why most people call the real stuff Wootz Steel or Wootz Damascus.