Missouri University of Science and Technology, Rolla, announces that a third-generation high-strength steel being developed by Missouri S&T metallurgical engineers should be lighter, easier to make, and strong enough to address automotive safety concerns. The technology is based on TRIP – transformation-induced plasticity. It involves the transformation of austenite, which normally exists at high temperatures, into martensite, a harder phase that develops as the steel deforms.
Because of their high fatigue strength and ability to absorb high amounts of energy, TRIP steels are well suited for automotive structures and safety components such as cross members, longitudinal beams, B-pillar reinforcements, and bumper reinforcements.
“We are currently refining the steel design to achieve ‘Gen 3′ mechanical property goals while also maintaining manufacturability,” says center director Dr. Ronald J. O’Malley, the F. Kenneth Iverson Endowed Chair of Steelmaking Technologies at Missouri S&T. “The alloy design is based on a two-stage or ‘dual TRIP’ mechanism that leads to extreme work hardening and energy absorption, so it’s very good for automotive crash-worthiness.”
Under the direction of Dr. David C. Van Aken, Curators’ Teaching Professor of metallurgical engineering, the Missouri S&T team has used an atomic modeling method known as “density functional theory” to identify alloying elements to create the dual TRIP character of these new steels.
The real challenge, however, lies with the large-scale production of these new steels. With the help of industrial partners, the researchers at Peaslee Steel Manufacturing Research Center are examining all aspects of the steel manufacturing – “from melt practice to final formability by the automotive producer,” Prof. O’Malley says. A committee of representatives from four steel manufacturers – Nucor, U.S. Steel, AK Steel and ArcelorMittal – oversees the project.
One benefit of conducting the research at Missouri S&T is the ability of researchers to create and test small batches of steel. In S&T’s labs, researchers can create 200 pounds of steel at a time, whereas big steel manufacturers like Nucor, where Prof. O’Malley was chief metallurgist before joining S&T, would have to make 170 tons of steel for testing.
