[HN Gopher] Stainless steel strengthened: Twisting creates submi...
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Stainless steel strengthened: Twisting creates submicron 'anti-
crash wall'
Author : wglb
Score : 76 points
Date : 2025-04-17 14:28 UTC (8 hours ago)
(HTM) web link (techxplore.com)
(TXT) w3m dump (techxplore.com)
| wglb wrote:
| Paper in Science:
| https://www.science.org/doi/10.1126/science.adt6666
| Gualdrapo wrote:
| I wish someone like Columbus/Reynolds/Tange could catch on this.
| It'd be awesome a road bike made of fancy/extra durable stainless
| steel tubing, lugged, horizontal top tube and that classic
| geometry but with disc brakes and thru axles.
| jeffbee wrote:
| Why though? Cr-Mo steel tubing is already superior to 304
| stainless in every relevant measure, except surface corrosion.
| In particular this article discusses fatigue behavior, and Cr-
| Mo has a (much) higher fatigue limit than 304.
| seethishat wrote:
| This is also true WRT knife steels. Old, simple carbon based
| steels are much stronger than most stainless steels. They
| tend to bend rather than chip or break (when abused). They do
| rust and do have less edge retention than some stainless
| steels (such as S90V), but otherwise they are generally
| stronger.
| jeffbee wrote:
| Totally. Just curious why the above wanted a stainless
| bike. If you want a steel road bike with disc brakes and
| thru-axles you can absolutely order one right now. I myself
| ride a Soma Wolverine with Tange Prestige Cr-Mo tubing,
| flat mount disc brakes, and thru-axles.
|
| If you wanted a bike that didn't necessarily need painting,
| you can order a bike like that in titanium tubing instead.
| lostlogin wrote:
| Thanks for that - Titanium bikes look amazing when bare
| metal.
| mjb wrote:
| That's just not true, though. Stainless (e.g. AEB-L) is up
| to four times tougher than simple low-alloy carbon steel
| (e.g. 1095). See
| https://knifesteelnerds.com/2021/10/19/knife-steels-rated-
| by... for example.
|
| High hardness simple carbon steels do have their place in
| knives, but what you're saying is factually incorrect.
| topspin wrote:
| > Cr-Mo steel tubing is already superior to 304 stainless in
| every relevant measure
|
| If you exclude cost as a relevant measure.
| gnopgnip wrote:
| Stainless is more expensive as well
| stickfigure wrote:
| The stainless steel construction helps with flux dispersal
| when you hit 88mph.
| hinkley wrote:
| Reynolds 501 is CrMo. But 531, which was more coveted,
| swapped the chrome for manganese, making it lighter at the
| same mechanical numbers.
| a_t48 wrote:
| Now that I have an aluminum bike I can't go back - lugging it
| up and down stairs is so much nicer.
| hinkley wrote:
| For me it was getting the fucking things into and out of car
| racks or trunks. Picking a bike up is not hard. Brandishing
| it at chest or head height is something else entirely.
| nabilhat wrote:
| They caught on, but with more appropriate stainless alloys.
| Columbus has XCr, Reynolds has 931. Either can be brazed, or
| silver soldered into lugs, or TIG welded. Cinelli does mass
| production of the bike you're describing, minus the lugs.
|
| 304 can't be optimized to a point it'll compete with the vast
| range of other stainless steels that already exist. Something
| else will always be more corrosion resistant, or stronger, or
| tougher. 304 exists on price. It's quick, common, and cheap.
| This process makes 304 expensive, uncommon, and slower to
| produce. The proven concept is what's carrying value here.
| ajuc wrote:
| Some medieval swords were made in a similar way (twisting and re-
| flattening the billet many times).
| accrual wrote:
| Pretty fascinating work. My layman understanding is they twist
| the steel in certain ways to create microscopic structures or
| patterns in the steel that then resist later deformation.
|
| It sounds kind of like the ripstop lines sown into X-Pac
| materials - when a rip or flaw occurs, its (ideally) bounded by
| the structures sown into the material.
| hinkley wrote:
| This sounds like very very careful work hardening.
| MisterTea wrote:
| It totally is.
| hinkley wrote:
| I sometimes watch machinists and blacksmiths on youtube.
|
| One of the things I've become more aware of lately is the fact
| that hardened steel eats through cutting tools like candy, so the
| solution is to anneal the steel, do most of the shaping, harden
| it again (temper it for as much as 24 hours in a very smart oven
| that slowly slowly drops the temps), and then finish the piece
| with sanding and grinding tools instead of cutting tools.
|
| I wonder if this treatment survives annealing and hardening
| cycles or if that just destroys the structure.
| MisterTea wrote:
| > very smart oven
|
| They just have PID temperature controllers with ramp/soak
| timers. They're really cheap these days.
| kazinator wrote:
| > _In testing the metal after treatment, the research team found
| it boosted its strength by a factor of 2.6 while also cutting
| strain due to ratcheting by two to four orders of magnitude
| compared to untreated stainless steel. Such improvements, the
| team claims, could allow products made using the metal to be up
| to 10,000 times more resistant to fatigue._
|
| LOL; that second sentence mainly just explains that four orders
| of magnitude means 10,000.
| MisterTea wrote:
| > The new technique involved repeatedly twisting a sample of 304
| austenitic stainless steel in a machine in certain ways. This led
| to spatially grading the cells that made up the metal, resulting
| in the build-up of what the team describes as a submicron-scale,
| three-dimensional, anti-crash wall.
|
| Interesting. Not a metallurgist but this takes advantage of
| stainless steels natural tendency to work harden. e.g. if you
| have ever broken a paperclip or other piece of steel by bending
| it back and forth until it fatigues, fractures, and beaks off.
| That happens in soft standard steels like A36 (edit forgot to
| finish this...) However, in stainless steel instead of a fracture
| forming at the bends crease, it hardens. As you try to bend it
| again, it bends in a new place as the original crease has
| hardened.
|
| > Such improvements, the team claims, could allow products made
| using the metal to be up to 10,000 times more resistant to
| fatigue.
|
| Very bold claim that if true is a game changer. My concern is how
| does this process scale to large complex structural pieces?
| Assuming since this internal structure will be ruined by
| annealing it must be performed after final shaping of the
| material. Welding should not be effected, especially low heat
| effect zone processes like laser and electron beam as you account
| for material alteration from welding during design.
| kristianp wrote:
| I'd like to have some of these stainless steel paperclips.
| Sounds like a good fidget toy.
| ggm wrote:
| I think this is discussed in "the new science of strong
| materials" by J.E. Gordon, (1968) alongside why some aluminium
| alloys get stronger if you "age" them before use.
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