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Steel Treatment Paves the Way For Radically Lighter, Stronger, Cheaper Cars (gizmag.com)
Zothecula writes: Radically cheaper, quicker and less energy-intensive to produce than regular steel, Flash Bainite is stronger than titanium by weight, and ductile enough to be pressed into shape while cold without thinning or cracking. It's now being tested by three of the world's five largest car manufacturers, who are finding they can produce thinner structural car components that are between 30-50 percent lighter and cheaper than the steel they've been using, while maintaining the same performance is crash tests. Grain of salt: the positive claims here are mostly coming from the company responsible for the process.
Before the days of unibody construction, usually the lifespan of a car was dictated by how long it took for the frame to rot, up here in New England anyway. I had a series of Subarus through the 1980s and 1990s that had perfectly running powertrains, but I had to retire them when the frames rotted away. If I got 150k miles out of them I was lucky.
Now I've had a few cars (an Impreza and a Honda Civic) with unibody construction, and now they seem to be limited by powertrain. The Impreza made it to 250k miles before the rings went, followed by the transmission. The Civic is still rolling nicely and passing emissions inspections at 300k miles, though I did have to replace the head gasket last summer.
I suspect the manufacturers are realizing that quality cars == low turnover == infrequent return customers. They'd love to make the automotive equivalent of a "One Hoss-Shay" that self-destructs after 100k miles as you drive past the dealership.
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A car's vulnerability to lateral gusts is a combination of not just its mass, but also its cross section and its lateral drag coefficient. Unfortunately the effects of winds not directly aligned forward/backwards are often ignored on cars, which is unfortunate - even ignoring gusts, you can have a very streamlined car whose drag coefficient goes to heck because it starts facing crosswinds. Part of that stream that you're working so hard to keep laminar and attached suddenly plunges off over the edge of your car in an uncontrolled manner and detaches - that's not a good thing, and it doesn't take that strong of winds to happen! It's something that's starting to get increasing attention, and hopefully will even moreso in the future - because a car's vulnerability to gusts and its fuel economy are tied together in the real world, particularly in windy areas. Some well-placed vortex generators over the doors for example could really help with both, maybe a sort of horizontal kammback approach as well.
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What I think of when I see these new thinner steel variants is that they must be a lot more sensitive to rust.
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Thankfully coatings technology is advancing faster than steel technology. Rust isn't nearly the problem in new cars today as it was before every steel component was coated at the factory.
Yes it's an anecdote! Were you expecting original research in a Slashdot comment?
The steel is similar to a maraging steel, but much easier and cheaper to produce. Instead of eliminating carbon and adding other alloying elements to form intermetallics like in maraging steel, they keep the carbon trapped as carbide particles for long enough to complete the heat treatment. Therefore only little alloying required. Nice! As already mentioned, the weakened welds limit the use of this material. Re-doing the heat treatment is not an option because the process relies on ultra-fast heating and cooling. Perhaps point welding is fast enough to keep sufficient strength?