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New steel treatment could enable lighter, stronger, cheaper cars (2015)
- 88e282102ae2e5b 10y agoHow can a metal be more ductile and also perform as well in crash tests?
- foota 10y agoI think the better that you deform under pressure the longer you have to resist the force against you. Imagine a car where the crumple zone instantly shatters upon impact, it would barely even be worth having, whereas one that deforms will resist the force while crumpling. (I'm a cs person, so excuse me if that's totally inaccurate)
- hanniabu 10y agoIt all depends if the force is along or against the bend.
- csours 10y agoDuctility, strength, and toughness are each separate things. In many cases, when metal gets stronger it becomes more brittle and less ductile, but this is not a fundamental relationship, in most cases it is an unwanted by-product.
- cjslep 10y agoOne view can be taken from applying conservation of energy. As a material deforms, it is absorbing energy and not transferring it to the vehicle nor the passengers. A brittle material will absorb less energy before shattering, letting the rest of the energy then be transferred to where you don't want it to be.
- maxerickson 10y agoIt's the energy in the passenger's body that is usually the issue. For instance, seat belts absorb the energy instead of the body flying through a window, crumple zones increase the time it takes to push the energy into a seatbelt (which decreases the force and thus the damage).
- Gibbon1 10y agoYeah this is correct. Less often talked about but actually very important, the amount of energy required to break something[1]. Also as ductile structures deform under load they tend to redistribute the load more evenly. [1] Hammer a piece of glass vs a piece of rubber.
- ars 10y agoI had the same question. I think they mean it can bend (without breaking), but it still takes a huge force to do so - more than the same metal with conventional treatment.
- honkhonkpants 10y agoYes, that's exactly right. Ductility is measured by how far a metal deforms before breaking entirely. Ultimate strength is measured in terms of how much pressure can be applied per unit of cross sectional area. A metal that can be elongated 50% while under 1000 MPa stress absorbs lots of energy. If a metal is less ductile, it will break after little deformation and therefore stop absorbing energy. Note that the metals under discussion here have very high strength (~1000-2000 MPa) and relatively little ductility (~10%), but are more ductile than other materials with this strength. On the other hand there are very ductile alloys that can tolerate 50% elongation and have strengths around 1000 MPa. These are achieved by adding basically a shitload (20% or more by mass) of manganese.
- eridius 10y agoI suspect that what you're imagining by "more ductile" is "it can be crumpled more easily", but I think what it really means is "it loses less strength when crumpled".
- sp332 10y agoAs stated in the article, it means that it can bend further without cracking. When metal has cracked apart, it isn't resisting force any more. If it is only bent, then it can still absorb more energy.
- emilong 10y agoIs anyone aware of other, non-automotive applications being discussed? I might have missed it in the article but it seemed like they only alluded to any. Construction? Maybe even aerospace?
- hanniabu 10y agoBoth are justifiable. Almost any manufacturing that uses press forming and relies on strength/weight.
- deleted 10y ago[deleted]
- dsfyu404ed 10y agoAerospace would be a big one. The few steel parts in aircraft are usually highly critical like landing gear attachment stuff and similar. Part of the reason they're steel is because they're spec'd to outlive the rest of the airframe by a huge margin and doing that with aluminum is impossible/impractical depending on the part and the safety margin.
- noir_lord 10y agoAlso failure mode, Aluminium tends to degrade gradually over time, it's cumulative and then fail where steel holds it's strength over it's life (as long as it's not exposed to loads over it's limits) which for a high impact/load environment like landing gear makes sense I guess. I'm a keen cyclist and some of the new steel frames are incredibly, they approach the same weight as aluminium frames with higher strength, better rigidity and they have (looked after) a basically indefinite lifespan. I think my next bike will probably be steel.
- Grishnakh 10y agoThat's funny. My bike is steel; I got it in college 20 years ago, so it's not new at all. At the time, it was pretty advanced I guess: it's a butted (triple? not sure) chrome-moly steel road bike by Trek. It's a little over 25 pounds I think, so it's really not that much heavier than comparable aluminum bikes. The frame's still in fantastic shape even though it's been ridden all over and not taken care of particularly well, been rained on a lot, etc. Not long after I got it, it seemed that steel frames became totally passé; everything went to aluminum, titanium, and then carbon fibre. These days, road bikes all seem to be either aluminum or CF. And now history repeats itself... Personally, though, I'm looking forward to ditching it and getting a recumbent trike. I'm getting sick of having a sore neck and shoulders and hands and having my arms go numb on long rides.
- lucio 10y agoVery nice, sounds like Rearden Steel, if you excuse my objectvism
- Osiris30 10y ago"Japan making steel 20-30% lighter and 25% stronger than the toughest high-tensile steel at the same price": http://www.nextbigfuture.com/2016/07/japan-making-steel-20-30-lighter-and-25.html http://www.nextbigfuture.com/2016/07/japan-making-steel-20-3...
- NamTaf 10y agoThere's a number of high-strength steels like this. Bisalloy [1] are an Australian group that produce Bisplate and SSAB [2] are a Swedish company that make similar products under the Weldox/Strenex/Hardox brands. As you mention, Nippon Steel also make a range of them. That said, neither is quite like this flash bainite. Both are very hard steels, so manufacturing and fabrication techniques need to suit the steels at hand. For example, machining the steels I listed can be very difficult and murders tooling bits compared to machining mild steel. Welding can also be difficult and usually involves significant preheating and post-weld heat treatment processes. Flash bainite apparently has some benefits in those areas but to what extent is hard to quantify. I'd love to know more about this flash bainite process, but their website is really scant on details. Other sources of info suggest that you weld the structure together then flash process it afterwards, which I'd assume is completely useless for anything with complex geometry or substantial size. A military report [3] of its performance shows that welding after FB treating literally halves its strength, as you'd expect since the heat of welding is basically like traditionally heat-treating it over longer durations. In that sense the ones I mentioned are better because you can more slowly heat treat them post-welding via more flexible methods that can deal with more complex shapes. This lets you get restored strength properties because those steels aren't reliant on a flash-style process. Where I think this reigns is in its ability to be formed easily whilst still being strong. Forming those steels I mentioned is a nightmare. In that sense it would certainly have applications where you can fabricate via fastening (rivets, bolts, etc.) but it seems to fall short when you need to weld it into anything more than a small butt-weld of two sheets. Certainly an interesting development and I'd love to see it realised to a commercial product as it'd definitely have some uses, but it's not the be-all-end-all holy grail of steel. [1]: http://www.bisalloy.com.au/ http://www.bisalloy.com.au/ [2]: http://www.ssab.com/products/brands/strenx http://www.ssab.com/products/brands/strenx [3]: http://www.dtic.mil/get-tr-doc/pdf?AD=ADA588144 http://www.dtic.mil/get-tr-doc/pdf?AD=ADA588144
- msandford 10y agoThe bummer here is that you have to heat treat very quickly and that means it won't work for thicker shapes.
- jdhawk 10y agoSerious Question: doesn't induction heating solve some of this? Also, it seems like they're focusing on tubing type structures.
- msandford 10y agoA little, but not really. You can only heat and cool things so fast, and the time is somehow related to the square of the thickness plus a bunch of constants. So if you worked really really hard you might be able to do stuff that's 1/4" or maybe even 1/2" thick but it'd probably never work for 6" thick. Yes they're focusing on tube because that's where it can be done. But if you could get very thick steel that's also stronger than Ti, that'd be AWESOME. Which is why I'm a little disappointed. This stuff isn't unobtanium, but it is a bit magical.
- mabbo 10y agoWhat really interests me is that it sounds like this isn't something high tech, just "never figured out before". It's a variation on the existing processes and yields a huge improvement at lower cost. How many more opportunities are the out there just sitting in front of us, unconsidered?
- dsfyu404ed 10y agoIf by unconsidered you mean "yeah we could mix X, Y and Z in different ratios to make an alloy with different performance characteristics but it's not worth doing because there's currently no market for an alloy like that" then there's s lot.
- tomhoward 10y agoThis looks like a hoax to me. I can't find any coverage of it in any authoritative news sources. If you google the address given on the company's website, it points to "Sculptors Fitness Center". Does any one have any knowledge to suggest that it's anything other than a hoax?
- honkhonkpants 10y agoThis site? http://www.flashbainite.com/ http://www.flashbainite.com/ Seems to work for me.
- honkhonkpants 10y agoHere's a detailed metallurgical survey of this material. http://www.dtic.mil/get-tr-doc/pdf?AD=ADA588144 http://www.dtic.mil/get-tr-doc/pdf?AD=ADA588144
- kragen 10y agoThis is a really exciting development in materials science. It's surprising and somewhat disheartening that it's taken me ten years to hear about it. https://patents.google.com/patent/WO2008042982A2/en https://patents.google.com/patent/WO2008042982A2/en seems to be the Flash Bainite patent application; if I'm reading this right, he's applied for a patent in the US and Canada, but neither has granted the patent after ten years. Note that Flash Bainite is a different material than bainite; Flash Bainite contains bainite crystals, but also contains crystals of other phases, including (in the case of AISI 4130) 82.5% martensite. Bainite as such has been known since the 1920s. I'm not completely clear on whether _sammcf is talking about this kind of flash-processed steel in their comments or about some other kind of steel in which bainite plays an important role, though it sounds like they're talking about this stuff. Putting the Rearden-Steel-like claims he makes in https://www.galtsgulchonline.com/posts/c0a47/hi-my-name-is-gary-cola-developer-of-flash-bainite-technology https://www.galtsgulchonline.com/posts/c0a47/hi-my-name-is-g... in context (thanks NamTaf!), the 2080 MPa strength he's claiming there is within a stone's throw of thin music wire, which is far and away higher than that of any other steel. But there's a huge difference in that the 10% elongation at break he's claiming is truly astounding — more like a plastic than a metal. Normal steels break at about 1% elongation, aluminum typically around 3%. Nylon 6,6 is typically around 30%. The ASM HTPro article http://www.asminternational.org/documents/10192/17082024/Pages+from+HTPro_December_2013_amp17111.pdf/61afa899-7863-4f83-9d5e-a7caa5e22eba http://www.asminternational.org/documents/10192/17082024/Pag... says they got UTS of 1.99 GPa and 10.2% total elongation for "flash processed AISI 4140". I'm not sure yet how much of that elongation is plastic, though judging by the OP's photo of the crumpled thing, maybe most of it. Bringing those two facts together, it would seem that it's substantially less stiff than ordinary steels, which means that even if all the claims are true, it won't replace them in uses where stiffness matters more than strength — uses like compressive structural members. Furthermore, the strengths discussed so far are ultimate stresses (after plastic deformation is exhausted), not yield stresses (stresses from which the steel will spring back), which may be unspectacular. In short, it's not a better steel. If these claims are true, it is in effect an entirely new class of material, that just happens to be made out of steel. Since you reach the Flash Bainite state by quenching, it seems likely that it's metastable and will eventually decay back into a more ordinary steel, but that's true of austenite too — for human applications, metastability is as good as stability if the time to relaxation is measured in billions of years.
- dsfyu404ed 10y agoWhat's the catch? Weldability, piss poor corrosion resistance/reactivity? "while aluminum is good for hoods, decklids and door skins, Flash offers higher strength per pound for structural safety components." So no more "like a mfg submarine" commercials or will they start making submarines out of it too?
- PeterWhittaker 10y agoWhat's the catch? Weldability...? I've just been chatting with a mech-eng materials specialist friend of mine, and according to him, you hit it, right there; he writes hot work will cause the microstructure to revert to classic regular BCC ferrite which isn't that impressive. that's the reason why you can't / shouldn't weld the stuff... ...essentially it's a "cast/quench this part and leave it the hell alone" material.