Article: "3D printing doubles the strength of stainless steel"

Spyderco's new Junction (by Gayle Bradley) FB features PSF27, "a high-performance spray-formed tool steel, known for its ultra-fine, homogeneous grain structure and superior edge retention properties." Not sure ifthat's a similar process, but interesting.
 
Alberta Ed said:
Spyderco's new Junction (by Gayle Bradley) FB features PSF27, "a high-performance spray-formed tool steel, known for its ultra-fine, homogeneous grain structure and superior edge retention properties." Not sure ifthat's a similar process, but interesting.
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It’s not.
 
flatface77 said:
I saw this & thought it might be of interest to my fellow forumites.

Link: http://www.sciencemag.org/news/2017/10/3d-printing-doubles-strength-stainless-steel

The first 3 paragraphs are filler. The last 3: "
The problem has been that, on a microscopic level, printed stainless steels are usually highly porous, making them weak and prone to fracture. “The performance has been awful,” says Yinmin “Morris” Wang, a materials scientist at Lawrence Livermore National Laboratory in California. Several years ago, Wang and his colleagues came up with an approach for using lasers and a rapid cooling process to fuse metal alloy particles together in a dense, tightly packed structure.

Now, they’ve extended that work by designing a computer-controlled process to not only create dense stainless steel layers, but to more tightly control the structure of their material from the nanoscale to micron scale. That allows the printer to build in tiny cell wall–like structures on each scale that prevent fractures and other common problems. Tests showed that under certain conditions the final 3D printed stainless steels were up to three times stronger than steels made by conventional techniques and yet still ductile, the scientists report today in Nature Materials.

“What they have done is really exciting,” says Rahul Panat, a mechanical engineer at Carnegie Mellon University in Pittsburgh, Pennsylvania. What’s more, Panat says, is that Wang and his colleagues used a commercially available 3D printer and laser to do the work. That makes it likely that other groups will be able to quickly follow their lead to make a wide array of high-strength stainless steel parts for everything from fuel tanks in airplanes to pressure tubes in nuclear power plants. And that, in turn, will likely only increase the growing fervor over 3D printing."

The link in the text leads to a nature.com article behind a paywall:
"Additively manufactured hierarchical stainless steels with high strength and ductility"

Link: https://www.nature.com/articles/nmat5021

Abstract: "Many traditional approaches for strengthening steels typically come at the expense of useful ductility, a dilemma known as strength–ductility trade-off. New metallurgical processing might offer the possibility of overcoming this. Here we report that austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibit a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels. High strength is attributed to solidification-enabled cellular structures, low-angle grain boundaries, and dislocations formed during manufacturing, while high uniform elongation correlates to a steady and progressive work-hardening mechanism regulated by a hierarchically heterogeneous microstructure, with length scales spanning nearly six orders of magnitude. In addition, solute segregation along cellular walls and low-angle grain boundaries can enhance dislocation pinning and promote twinning. This work demonstrates the potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications."
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They must have hooked up a turbo encabulator to their 3D printer.
 
About six months back I contacted two 3D printing companies via email and on Twitter and asked them if 3D printing technology had advanced enough to produce a knife blade. After about two weeks of poking around I found that 3D printing of a high quality knife blade was not yet possible, but I do think it is on a 5 to 10 year horizon. I was thinking it would be a unique market position for knives.

The problem is not with handles, a 3D printer can knock out a handle with ease. Handles do not have problems with less than complete passes of the head that the system uses. Also, you face the problem of materials.

The big issue is steel. One of the companies directed me to a company that specializes in steel for 3D printers. The company in question had three or four metals that could be used in a 3D printer. I did not see any of the AUS-8, 3V, S35VN, VG-10 type steels, these are all very basic nonstainless and stainless, wherein you cannot guarantee a blade without dropouts. At the moment you might be able to produce some art knives in a steel of unknown quality but don't expect to turn anything out that is a high quality fighting or even kitchen knife.

We just aren't there yet.
 
I don't think that 3d printing will ever really be viable to create blades. It doesn't add any advantage to design, even if the materials problems are solved. We already know that a blade needs to be heat treated, and that the steel needs to be as close to flawless as possible. Any sort of additive manufacturing will have induced a lot of thermal stresses, as well as flaws. In other uses these things can be engineered around, and there is an advantage to using additive methods. But for a knife blade, I just don't see it. I suppose that if it did get nearly good enough, you could make a hollow blade, but why?
 
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