Posted on 25 Mar 2015
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Feb 05, 2015 - A trio of researchers with South Korea's Graduate Institute of Ferrous Technology has found a way to create a new low-density steel that is stronger, lighter and more flexible than the conventional steel that is used in so many manufacturing applications. In their paper published in the journal Nature, the team describes the process they used and their hopes that it might replace conventional steel in some applications sometime in the near future.
One of the biggest applications for steel is, of course in making cars, though its dominance has been slipping in recent years as engineers seek to find lighter substitutes. At issue is weight, steel is heavy because it is made mostly out of iron. Adding other lighter metals tends to make it less flexible or weaker. In this new effort, the researchers report that they have found a mix that allows for creating a low-density steel that is stronger and more flexible than much more expensive titanium alloys.
The secret, the team explains, lies in causing new structure shapes to be formed during the heating process and by using the right mix of ingredients. They used the traditional mix of iron, carbon, aluminum and manganese and then added some nickel. The nickel, they found reacted with the aluminum, creating nanometer sized B2 crystals that formed within and between the steel grains during the annealing process. To make sure the crystals were spread evenly among the metal, the team studied samples under an electron microscope. Chemists know that B2 crystals are resistant to shearing, thus steel with such crystals should be extremely strong, and that is what the researchers found when they tested their new alloy.
The researchers have already teamed with POSCO, one of the biggest steel makers in the world to see if the new kind of steel they have come up with might be usable in cars or even airplanes. The first step will be to see if the process is scalable, and if so, if it can be used to produce the new low-density steel at a cost that is competitive with conventional steel—the researchers are optimistic because all of the ingredients are low cost metals.
