Steel Process May Boost MPG

DETROIT-AREA DO-IT-YOURSELFER AND self-taught metallurgist Gary Cola says he is creating steels that are 7% stronger than conventional steels and even tougher than some titanium alloys.

Astonishingly, Cola's process takes a mere 10 seconds.

He calls the new steel Flash Bainite and is now working with Ohio State University researchers to determine the science behind his processing treatment. OSU researchers say Flash Bainite steels might lead to lighter, stronger and more fuel-efficient cars and military vehicles.

Cola and the OSU research team describe how rapidly heating and cooling steel sheets changes the microstructure of the metal to make it stronger and less brittle.

“Steel is a mature technology, (and) we'd like to think we know most everything about it,” says Suresh Babu, associate professor of materials science and engineering at OSU. “If someone invented a way to strengthen the strongest steels even a few percent, that would be a big deal.

“But 7%? That's huge.”

When Cola first described his process, Babu didn't believe him. “The process that Gary described — it shouldn't have worked.”

To convince the educator, Cola brought him and his students to his workshop north of Detroit.

At his lab at SFP Works, Cola demonstrated his process: Rollers carry steel sheets through 1,948° F (1,100° C) flames and then into a cooling liquid bath. Typical temperature and time for steel hardening varies in the industry. Usually it's about 1,588° F (900° C) for a few hours, and as much as up to a few days for some varieties.

Cola's process lasts less than 10 seconds. He claims his martensitic steel can be drawn (thinned) and lengthened 30% more than conventional martensitic steels without losing its enhanced strength.

If that can be duplicated in a factory, Cola's steel could be used to build body shells up to 30% thinner and lighter, without reducing safety. It also could be used to reinforce armored vehicles without adding weight.

The OSU researchers used an electron microscope to confirm Cola did create martensite microstructure inside his steel. They also discovered bainite microstructure scattered with carbides in the steel.

Babu says in traditional steel making the initial microstructure always dissolves into an austenite at peak temperature. But when cooled rapidly from high temperature, the austenite is transformed into martensite.

“We think that, because this new process is so fast, the carbides don't get a chance to dissolve completely within austenite at high temperature, so they remain in the steel and make this unique microstructure containing bainite, martensite and carbides,” Babu says.

One additional feature of Flash Bainite is its enhanced ductility. This allows it to crumple before breaking and improves its capability for absorbing impacts.

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