Damascus steel is practically synonymous with artisanal forgework, but 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:
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.
Rapid cooling of this steel also produces a crystalline form as in quenched high-carbon steels. But further heat treatment leads to the precipitation of microscopic nickel-titanium particles within the steel that greatly increase its hardness—a pricey material called “maraging steel.”
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 first test piece was thrown under the microscope for an incredibly detailed analysis, including a close-enough look at the hard layers to see the precipitated particles. The researchers even atom mapped the layers to verify their composition. So the researchers were able to confirm that the process definitely accomplished what they were aiming for.
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For comparison, they printed another block continuously, producing no hardened layers at all. Both were stretched until they fractured and failed.
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.”
The Sea Dragon a 79,000,000 lbf thrust first stage space rocket was be made of maraging steel. They were to use a kind of drag balloon to crash it into the sea for reuse.
What the launch should look like.
https://www.youtube.com/watch?v=SRMDcC0QvFQ
Instead of building the SLS (a huge rip off) we should have built this and used methane and liquid oxygen as fuel. If we needed less payload we could just put less fuel in it or launched fuel tanks to store in earth orbit for later.
It’s glorious.