Back in 2011, we wrote about a fascinating new way to heat-treat regular, cheap steel to endow it with an almost miraculous blend of characteristics. Radically cheaper, quicker and less energy-intensive to produce, 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. Those are revolutionary numbers in the auto space.
Darren Quick did a good job explaining exactly how Flash Bainite is produced in our original story, but in basic terms, you take regular, off-the-shelf AISI1020 carbon steel, and instead of heat treating it for 10 minutes like costly alloyed steel, you put it through a roller-driven system that induction-heats and liquid-cools the steel in a matter of 10 seconds or so.
Generally, when you choose steel you’re trading off between strength and ductility. The hardest steels are the martensitic types, but their crystalline structure makes them brittle and prone to cracking when you press or bend them, so they need to be hot pressed. Flash Bainite breaks this rule by delivering a specific strength some 7 percent higher than martensitic steel but staying remarkably bendable to the point where it can be cold pressed into shapes. The quick heating and cooling stages produce a unique mix of fine martensite, bainite and carbides – if you want to get all metallurgical about it, knock yourself out.
With such characteristics, you could theoretically take anything you’re making out of martensitic steel and make it stronger and vastly cheaper, or take many shapes you’re cold pressing out of more ductile steel and use vastly thinner Flash Bainite to get the same strength. It sounded almost too good to be true, but recent testing from a number of different parties appears to be validating the original findings.
Read more: Revolutionary steel treatment paves the way for radically lighter, stronger, cheaper cars
