How to 3D-print one of the strongest stainless steels
nist.gov
nist.gov
One difference is, NASA's work uses Hot isostatic pressing [1], a post-processing step that homogenizes the part. Whereas it sounds like this work is trying to dial in the composition such that they can get acceptable performance without any post-processing.
Tesla went through a similar thing with their Gigacastings. The only reason making such large die-cast parts is practical for them is, they put a lot of work into the material science to come up with a composition they gave the desired properties without any post-processing such as heat treatment.
The really cool thing NASA is doing, though, is coating the metal powder with nanoscale ceramic particles, which get dispersed throughout the part. That's something that can't be done with traditional manufacturing at all (the ceramic particles would separate out of molten metal rather than staying dispersed). With 3D printing, each little melt pool is too small for the ceramic particles to migrate too far, and after HIP they end up at the grain boundaries. Using that approach, they developed an alloy with higher ultimate tensile strength and vastly higher (x1000) resistance to creep at high temperatures (1100 C) compared to the best available superalloys.
That sounds really cool. Do you think this will allow us to build jet engines with higher operating temperatures, improving efficiency of electricity generation and plane travel?
I don't have one (yet), but the results on sound signature look to be pretty impressive [2].
[0]: https://cgsgroup.com/product/hyperion/
[1]: https://www.sigsauer.com/suppressors.html
[2]: https://pewscience.com/sound-signature-reviews-free/sss-6-71...
For example the foam used in the below one wouldn't be useful for a kitchen hood fan.
https://www.amazon.com/VIVOSUN-Noise-Reducer-Silencer-Inline...
?
Are there legitimate uses of a suppressor I'm unaware of, or are they truly only useful for clandestine violence?
Banning suppressors is kinda like as if European countries today banned possession of English longbows. These very much can be effectively used for violence, as Agincourt has shown. However, nowadays, they emphatically are not used for that, and if modern European government loudly declared a war on longbows, and went after the owners, one would think that they went crazy: shooting longbows is a pastime of medieval reenacters, not criminals.
Firearms with suppressors are still very loud (>130 decibels or about as loud as an ambulance siren) [1].
[1]: https://en.wikipedia.org/wiki/Silencer_(firearms)#Effectiven...
The American suppressor market is super interesting, because the $200 flat tax, extreme physical stresses, and low weight limits conspire to incentivize some of the most advanced high-temperature high-stress metallurgy outside of jet engines. In most other countries, where suppressors are unrestricted or even required (!), it seems like there's not nearly as much incentive to go straight to the ultra-high-end like most American suppressor mfrs have done.
https://makezine.com/article/digital-fabrication/machining/1...
This is the future. We aren't even remotely close to scaling up and optimizing this kind of manufacturing.
https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=93265...
"Characterization of phase transformation dynamics of commercial additively manufactured 17–4 stainless steel (C_17–4) during laser melting. (a) Schematic illustration of in-situ laser-melting X-ray diffraction experiment. A vertical laser beam scans the sample to create a localized melt pool. The micro-focused high-energy X-ray beam is used to probe the phase transformation dynamics with a frame rate of 250 Hz. (b) Room temperature XRD pattern of as-solidified C_17–4 after laser melting. (c) XRD intensity map (XRD peak intensity evolution as a function of time) during laser melting of C_17–4 from 0 s to 20 s. The liquid gap near 0.15 s without any diffraction peaks denotes the period when all the material in the X-ray path was fully melted. The time axis is enlarged in the 0–1 s range to highlight the phase transformation details during the initial solidification stage. (d) EBSD of as-printed C_17–4 microstructure displayed in inversed pole figure (IPF) coloring. (e) EBSD of as-printed C_17–4 microstructure displayed in image quality (IQ) map. Martensite (α’) phase and a mixture of austenite (γ) and δ-ferrite (δ) phases were pointed out in the microstructure. (f) EBSD phase map of as-printed C_17–4. (g) XRD intensity evolution from (c) during solidification. The time axis is enlarged in the 0–1 s range. The uncertainty for BCC intensity measurement is 1 %. The uncertainty for FCC intensity measurement is 2 %."
I'm assuming there would be features that need to be cleaned up after a print, but this looks incredible.
I wonder what the cost savings are like vs a 6dof CNC mill for parts that can be made that way.
6-axis, dof is the wrong term here.
Someone else posted a link to the paper
One of the difficulties in adoption I see is finding ways to assure the process and the materials that industry will trust and adopt.
Conventional procurement of exotic or high-performance/high-spec materials can typically include destructive and non-destructive testing to confirm properties at different stages in the supply chain. This is relatively straight forward if you are getting bar or plate stock. You take some bits off and test those separately knowing everything from the same mother-plate will perform the same.
In an additive process, I don't know what that looks like, or what would satisfy those who need it (usually insurance companies). Do you print an extra tab onto the part, or a seperate piece in the same print run? Or is it the consumables (i.e. the metal powder) that you QA, similar to how welding consumables are QAed. Maybe a combination? Either way, it could be a while before industry adopts a standard approach to this.
In a similar but different vein, Modumetal use nanolamination to get the structures they need. I've always wondered why they don't try to match to current steel specs, maybe they can't, maybe it's not a business model that would work for them. https://www.modumetal.com/
Also, "one of" should be emphasized there. 17-4 is very good common steel. But there are tons like inconel (a tradename for a 600 series), or maraging steels that beat in strength applications. It's good, but it's common good. Not common great. And certainly not exotic good.
As a machinist, you had better have a good plan before get into inconel. For 17-4, you can pretty much just have at it.
There is no PH step here. That typically involves heating the metal and spraying it with a solution that contains different metals. Some steel is hard to heat treat in the typical way (heating/quenching), but precipitation hardening may work differently. It gets real science real fast.
I don’t know all the ins and outs, but I suspect the article was taking liberties in “just as good” being “the same”. That was my point, they might have made something great, but without sprinkling it was copper or chromium or whatever solution, it’s not PH.
So I think you're right that it won't be 17-4 PH. It sounds like it could be just as strong without the need for heat treating. That's pretty cool.
Humans create a better vaccine? "This is great, but we should be aware there are real and dangerous consequences as this technology advances."
Humans create more efficient solar cells? "This is great, but we should be aware there are real and dangerous consequences as this technology advances."
I never know when I'm replying to something that may be tongue in cheek or sarcastic. I'd suggest that we need better NLP tools to extract semantic meaning from web comments, but "we should be aware there are real and dangerous consequences as this technology advances."
Maybe someday it'll be as affordable as FDM is now.
But the raw parts are probably an order of magnitude cheaper, so price should come down to those levels if production scales up.
Is this just a fancy way of saying it doesn’t require heat treatment?