Dream Material for Cars
A Korean research team has successfully developed a technique to produce a new type of steel that is 50 percent stronger, better processed, and much lighter than conventional steel used to make cars.
A research team consisting of professors Kim Nak-joon and Kim Han-soo from Pohang University of Science and Technology announced on Feb. 4 that they have succeeded in developing a technique to make strong, light, and flexible steel, which is second only to titanium. It was done so by adding aluminum to iron and controlling the crystal structure formed.
So far, many studies have been conducted in the global auto industry to lower the weight and augment the strength of steel by alloying it with aluminum in order to increase mileage. However, an increase in the amount of aluminum weakens the structural strength of the resulting alloy, and it shears easily rather than bend.
To address the problem, the research team was able to develop a technique that enabled them to make an alloy with a small enough amount of aluminum that it did not break easily. They were also able to evenly distribute the aluminum throughout the structure of the alloy using the method.
Specifically, they used 0.8 percent carbon, 15 percent manganese, 10 percent aluminum, and 5 percent nickel into steel, and processed the alloy at 900°C, which is generally used for heat treatments. After that, they decreased the size of the compound to evenly diffuse it into a larger amount of steel.
A steel compound evenly diffused in the steel structure has more strength, and thus it plays a role in pinning the movement of the alloy in the surrounding area, when the shape of steel changes because of an exterior force. The compound becomes stronger and more flexible as a result.
The newly-developed steel turned out to be 50 percent stronger, up to 15 percent lighter, and more flexible than existing steel for automobiles, and thus it did not break easily when applying forces.
The new material has proven to be similar to titanium in strength, and was able to flex more than twice as much. The research team explained that it was easy to change the shape of the material, and it only costs one tenth of the price of titanium.
A standard-essential patent was first filed for the study in 2013, and POSCO is planning to start production testing of the material soon.