Can you 3D print Damascus steel? Pretty much, yeah | Hacker News Reader

Can you 3D print Damascus steel? Pretty much, yeah

arstechnica.com

41 pointsBerislavLopac10 comments

This process produces steel where the soft layers are ~3 mm thick and the hard layers are ~0.25 mm thick. The layers could probably be thinner. My understanding is that the minimum layer thickness of this process is ~0.01 mm. The hard layers are created by rapid cooling; i'm not sure if the dynamics of the cooling process itself would create layers thicker than that.

The steel used in the traditional Japanese sword-making referred to in the article has layers far thinner than that. If a sword is 7 mm thick at the hilt, and the steel has been folded 16 times, then the layers are 0.1 um (a tenth of a micron!) thick.

Actual Damascus steel is something else entirely:

https://en.wikipedia.org/wiki/Damascus_steel

But it's still a really cool process!

I like the idea of using the laser for that - it'd allow for a more interesting 3D arrangement than folding and layering of different hardness materials. An obvious one is interlocking structures of hard/soft steel within the part.

That would be amazing. I'm not sure they can do that, though. From the article:

> 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.

The way they make the hard layers is by turning the laser off for a couple of minutes and letting the freshly-melted metal cool quickly. When you do that, everything that's hot and exposed will harden. Maybe you could use the laser to keep some areas of the metal hot while others harden? Or does the metal conduct too much heat to do that? Maybe you could build some areas up, then cool them slowly to make soft metal, then build up the gaps between those and cool them rapidly to make hard metal?

> Maybe you could use the laser to keep some areas of the metal hot while others harden? Or does the metal conduct too much heat to do that? Maybe you could build some areas up, then cool them slowly to make soft metal, then build up the gaps between those and cool them rapidly to make hard metal?

That's pretty much what I was thinking

Does anybody else find this idea that forge welded steel == damascus steel annoying? I don't really know what damascus steel is supposed to be, but forge welding isn't exactly an arcane technique, and certainly didn't originate in damascus. Calling forge welded steel damascus also seems to imply it should be unusually strong or whatever, which is not necessarily the case. I'm not even sure if there was another method of welding prior to the invention of resistance welding.

According to Wikipedia, Damascus steel really means something more specific:

“Damascus steel was the forged steel of the blades of swords smithed in the Near East from ingots of Wootz steel imported from Southern India and Sri Lanka.“

“Although many types of modern steel outperform ancient Damascus alloys, chemical reactions in the production process made the blades extraordinary for their time, as Damascus steel was superplastic and very hard at the same time. During the smelting process to obtain Wootz steel ingots, woody biomass and leaves are known to have been used as carburizing additives along with certain specific types of iron rich in microalloying elements. These ingots would then be further forged and worked into Damascus steel blades. Research now shows that carbon nanotubes can be derived from plant fibers, suggesting how the nanotubes were formed in the steel.”

> "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.”"

Of course. Damascus steel gets its properties because of folding metal times and times and hammering. Piling layers with different properties has nothing to do with making "something that looks alike but is not at all" damascus steel...

Maraging steel used to be an input for hexafluoride centrifuges.

There are many theories as to what made "Real Damascus" special. My personal favorite is the vanadium theory, because my grandpa had a set of vanadium steel box wrenches and they were indeed neigh indestructible.

https://howiefirth.wordpress.com/2012/03/25/damascus-swords-...

I wonder how they handle warp when the temp cycles.

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