Audi has had an all-aluminum body in its A8 model since 1994, but now is switching back to steel, including some supplied by ArcelorMittal.
That's because steel has evolved dramatically over that time period, and now comes in grades 10 times stronger than what was available 20 years ago. ArcelorMittal has developed nearly 200 different steel grades for automakers, and is currently working on 80 additional advanced high-strength steel products, including at ArcelorMittal Global R&D in East Chicago.
Only 8 percent of the Audi A8 body structure was steel in 2009, but the 2018 model will be 40.5 percent steel, including press-hardenable steel supplied by ArcelorMittal.
“Usibor is our key product in hot stamping and has been a major commercial and technical success in the global automotive industry,” said Brian Aranha, executive vice president, global automotive, ArcelorMittal. “Looking ahead, the scope of hot stamping products in vehicles will continue to increase with the release of more advanced products like Usibor 2000, which offers 10 to 15 percent weight savings when compared to existing hot stamping solutions.”
The use of advanced high-strength steels in cars has grown from 81 pounds per vehicle to 2006 to 275 pounds of steel per vehicle in 2015, according to the Steel Market Development Institute. It's outpaced forecasts, increasing in use by 10 percent each year from 2012 to 2015.
"There will be no cars made of aluminum alone in the future," said Bernd Mlekusch, head of Audi's Lightweight Construction Center. "Press-hardened steels will play a special role in this development. PHS grades are at the core of a car’s occupant cell, which protects the driver and passengers in case of a collision. If you compare the stiffness-weight ratio, PHS is currently ahead of aluminum."
ArcelorMittal has been working to drum up more business for its advanced high-strength steels, some of which are produced in Northwest Indiana, saying they result in fewer emissions than aluminum when production and recycling are factored in.
“Right now, regulations only consider tailpipe emissions generated during the drive phase,” said Brad Davey, chief marketing officer, NAFTA and global automotive for ArcelorMittal. “However, each material used in vehicle production contributes to lightweighting and improves fuel economy, but each does so at a different cost to the manufacturer — and to the environment.”