Northwest Indiana is making much stronger grades of steel for the next generation of lighter automobiles.
Steelmaker ArcelorMittal cranks out a number of advanced high-strength steels that are significantly stronger so automakers can use less of them in cars, cutting down on weight, fuel use and emissions while maintaining crash protection.
At ArcelorMittal Indiana Harbor in East Chicago, local steelworkers produce four grades of MartINsite and will soon add two more martensitic steels, MartINsite M1700 and M200. A martensitic steel is a very hard form of the metal that's made through the process of diffusionless transformation, which is when atoms are moved to change the metal's crystal structure. Commercial production of the new grades is expected to start in 2018.
“It’s almost 10 times stronger than regular mild steel,” said Blake Zudeima, director of Automotive Product Applications at ArcelorMittal. “It’s the magic of metallurgical thermal processing; you can have different structures in the steel to get very high strength. You adjust the chemistry a little bit, use a slightly different cooling process and it’s a hugely different end product.”
A continuous annealing line at the former Inland Steel mill, now ArcelorMittal Indiana Harbor East, in East Chicago, has made MartINsite for 30 years. Originally, the stronger metal was for saw blades and plow discs, but automakers have long seen its potential.
“In the early 1970s, the oil embargo got the car industry interested in fuel economy,” Zudeima said. “They’ve increasingly been interested in advanced high-strength steels to get there.”
Steel is an obvious target for weight reduction since it comprises an estimated 60 percent of the weight of the average vehicle on the road. And automakers have accelerated their push to cut the weight out because of federal emissions standards that require their fleets go from an average of 27.5 miles per gallon in 2012 to 54.4 mpg in 2025.
Even if the new administration were to repeal that regulation, automakers would still continue the push to “lightweight” vehicles because of consumer demands and similar regulations in markets around the world, said Charles Bradford, a steel industry analyst for New York City-based Bradford Research Inc.
Virtually every domestic and foreign automaker is now using martensitic steels, which rival U.S. Steel is also now producing for automotive customers, Zudeima said. The strong grade goes into bumper beams, door beams, anti-intrusion side door beams, seat frames, lockers, crossmembers, roof rails and other car parts.
“It has slowly worked its way into more and more applications,” he said. “It’s one of the highest strength grades of any car part. It’s relatively limited in formability. It has to be roll formed. It can’t be stretched like taffy.”
ArcelorMittal has been trying to use advanced high-strength steel to preserve its automotive market share as alternatives like aluminum, plastic and even magnesium try to gain ground. The American Iron and Steel Institute estimates automotive makes up 27 percent of the overall steel business in the United States. Northwest Indiana’s huge integrated mills on Lake Michigan are strategically located to serve all the automotive factories in Michigan, Indiana, Ohio and Kentucky.
Chicago-based ArcelorMittal USA and other steelmakers pitch their advanced high-strength steels as the most environmentally responsible option with the lowest overall carbon footprint, as well as being the lowest cost option.
Martensitic steels also hold up in crashes far better than traditional steels.
“It’s very strong,” Zudeima said. “It does not crumple.”
The MartINsite grades of steel produced in East Chicago are crucial to ArcelorMittal’s overall automotive business, which is one of its core markets.
“MartINsite is an integral part of our lightweighting strategy,” he said. “It helps provide weight reduction to get us to the future fuel economy goals, which is critical to the long-term viability of steel in cars.”