New steel treatment could enable lighter, stronger, cheaper cars (2015)(newatlas.com)
newatlas.com
New steel treatment could enable lighter, stronger, cheaper cars (2015)
http://newatlas.com/flash-bainite-automotive-testing/40774/?li_source=LI&li_medium=default-widget
44 comments
The bummer here is that you have to heat treat very quickly and that means it won't work for thicker shapes.
Serious Question: doesn't induction heating solve some of this? Also, it seems like they're focusing on tubing type structures.
A 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.
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.
How can a metal be more ductile and also perform as well in crash tests?
One 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.
Yeah 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.
[1] Hammer a piece of glass vs a piece of rubber.
It'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).
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).
Ductility, 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.
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.
As 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.
I 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.
Yes, 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.
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.
I 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)
I 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".
It all depends if the force is along or against the bend.
Is 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?
Aerospace 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.
Also 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.
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.
That'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.
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.
If the hand numbness is really bad consider switching to a carbon fork if you haven't already, on my old aluminium bike the numbness was pretty bad since I switched to a carbon bike it's largely gone.
How is having a stiffer front fork going to help? (My front fork is steel; my bike is not stiff.)
It's not so much the stiffness that matters but that carbon damps the 'buzz' from the road, Steel is better than Aluminium but Carbon is better than both in my experience.
That said if you are having real numbness problems switching up to a 25mm tyre (most road bikes will take them) and running at 80psi vs 23mm at 110psi will make the most difference.
It also depends on the surface you ride on, UK roads are not known for been particularly smooth (particularly rural two lanes) so the differences are more marked.
That said if you are having real numbness problems switching up to a 25mm tyre (most road bikes will take them) and running at 80psi vs 23mm at 110psi will make the most difference.
It also depends on the surface you ride on, UK roads are not known for been particularly smooth (particularly rural two lanes) so the differences are more marked.
Thanks for the advice; I do believe I have a 25mm tire in front (I'll have to check, but it's not super-thin). But a CF front fork sounds like way more money than I want to spend on fixing up a 20+ year old bike; if I'm going to spend any money, I might as well get a new bike, which is why I'm seriously looking at getting a Catrike: I can get away from the uncomfortable road bike posture altogether that way, get better aerodynamics, avoid crotch pains, etc.
Recumbents have a lot to recommend them but I don't like the lack of visibility in traffic, UK drivers aren't that considerate of cyclists generally so I at least like to be visible, that said they do really really move compared to a road bike since the aerodynamic shape helps hugely.
I'm in the US, and roads here are really bad for riding bikes on, unless you're in a very small town or something. (Even that isn't a great place; I live in a small town currently and the street in front of my house has a 25mph speed limit, but people are constantly speeding on it, and frequently hitting cats that cross the road near my house.) That's why I simply don't ride on roads with cars if I can help it; I mostly stick to rail-trails or towpaths. I can ride 40 miles on a rail-trail and barely see any cars at all, and frequently not even any humans.
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Both are justifiable. Almost any manufacturing that uses press forming and relies on strength/weight.
Very nice, sounds like Rearden Steel, if you excuse my objectvism
Objectivism Shrugged :-)
This is an amusing statement given it seems like he's a bit of a Randian: https://www.galtsgulchonline.com/posts/c0a47/hi-my-name-is-g...
"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-20-3...
http://www.nextbigfuture.com/2016/07/japan-making-steel-20-3...
There'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/
[2]: http://www.ssab.com/products/brands/strenx
[3]: http://www.dtic.mil/get-tr-doc/pdf?AD=ADA588144
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/
[2]: http://www.ssab.com/products/brands/strenx
[3]: http://www.dtic.mil/get-tr-doc/pdf?AD=ADA588144
I currently source a number of castings in bainite for ground engaging agricultural parts and it is what I would call semi-weldable - you wouldn't rely on a structural mig weld but I've had success with both tig welding and silver solder for attaching other parts with non-structural joins.
The big win for me is the parts can be air quenched - the slower cooling eliminates one of the biggest rejection flaws, straightness
The big win for me is the parts can be air quenched - the slower cooling eliminates one of the biggest rejection flaws, straightness
If I'm understanding you correctly, you touch on the point that I (probably badly) tried to make - by slowly cooling it during heat treatment, you can post-weld treat it to remedy issues that the HAZ introduces. I'll try to explain it again because I've probably also confused others.
For example, when I deal with the castings I procure, we mandate that the supplier either repairs them prior to the heat treatment stage or they must be fully heat treated again after weld repairs. This helps resolve the otherwise brittle HAZ. You can do this, because castings are usually quench-and-tempered, which is a relatively slow process.
Welding stuff like Bis, Weldox, etc. requires both pre- and post- heat treating in order to let the weld form and also address the HAZ properly afterwards to restore its strength. You can do this because the processes to heat treat it are traditional and relatively slow. This lets you get (somewhat reduced compared to the parent metal) structurally sound levels of strength out of the weld locality. Because of it, Weldox and Bis both see widespread use in truck bodies, crane arm trusses, etc.
This is in constrast to flash bainite, which relies on it being a very fast process. By virtue of it being a fast, tailor-made process you can't just do it to a complex geometry. By welding it, you dump heat into the weld which then air-cools slowly as the weld cools, completely running counter to the flash bainite process that is necessary to produce the strength. That's why you see a halving in UTS in the mil report I linked in source 3 of my first post - you simply can't recover from the slower heat-and-cool process without doing the whole treatment again, and you can only do that on easy geometries (it seems).
As said, if I understand what you're saying we're essentially saying the same thing, but I think I phrased it quite badly in my post. Not that you disagree with me, but it just made me realise that I don't think I worded it well and wanted to clarify.
For example, when I deal with the castings I procure, we mandate that the supplier either repairs them prior to the heat treatment stage or they must be fully heat treated again after weld repairs. This helps resolve the otherwise brittle HAZ. You can do this, because castings are usually quench-and-tempered, which is a relatively slow process.
Welding stuff like Bis, Weldox, etc. requires both pre- and post- heat treating in order to let the weld form and also address the HAZ properly afterwards to restore its strength. You can do this because the processes to heat treat it are traditional and relatively slow. This lets you get (somewhat reduced compared to the parent metal) structurally sound levels of strength out of the weld locality. Because of it, Weldox and Bis both see widespread use in truck bodies, crane arm trusses, etc.
This is in constrast to flash bainite, which relies on it being a very fast process. By virtue of it being a fast, tailor-made process you can't just do it to a complex geometry. By welding it, you dump heat into the weld which then air-cools slowly as the weld cools, completely running counter to the flash bainite process that is necessary to produce the strength. That's why you see a halving in UTS in the mil report I linked in source 3 of my first post - you simply can't recover from the slower heat-and-cool process without doing the whole treatment again, and you can only do that on easy geometries (it seems).
As said, if I understand what you're saying we're essentially saying the same thing, but I think I phrased it quite badly in my post. Not that you disagree with me, but it just made me realise that I don't think I worded it well and wanted to clarify.
Yep we are in 100% agreement. To rectify my own lack of clarity, the sort of parts I am talking about are largely prismatic with a handful of holes and pockets, or for the more complex geometry, not more than around 300x300x300 in total envelope, so definitely not large.
For reference, bainite has completely replaced 8630 in all ranges of quenching and tempering as a material for us, and I'm currently in the process of phasing out most of our Hardox parts in lieu of bainite as well. Haven't used Bisalloy plate for years due to its even-worse-than-expected machinability.
For reference, bainite has completely replaced 8630 in all ranges of quenching and tempering as a material for us, and I'm currently in the process of phasing out most of our Hardox parts in lieu of bainite as well. Haven't used Bisalloy plate for years due to its even-worse-than-expected machinability.
Also as a curiosity I've successfully heat treated bainite stock that was mistakenly supplied raw with a butane torch, an infrared thermometer and a water bath. The end result was slightly softer and slightly tougher than the parts heat treated at the foundry at time of casting.
Basically it is a fantastic material and I want to marry it.
Basically it is a fantastic material and I want to marry it.
Happy to see people working with agriculture hanging around here!
What 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?
How many more opportunities are the out there just sitting in front of us, unconsidered?
If 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.
This 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?
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?
Here'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
This site? http://www.flashbainite.com/ Seems to work for me.
This 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 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-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/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.
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-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/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.
What'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?
"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?
What'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.
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.