Auto makers are rediscovering steel.
Varieties of lighter, stronger steel are being used in Fiat Chrysler Automobiles NV’s Pacifica van, Honda Motor Co.’s Ridgeline pickup truck and General Motors Co.’s Chevrolet Malibu sedan.
Audi AG, which switched to an all-aluminum body for its A8 sedan more than 20 years ago, is using steel again on the latest model. “It’s the strongest and most rigid A8 we’ve built,” said Audi spokesman Mark Clothier.
An ArcelorMittal plant in Hamilton, Ont. The steelmaker expects auto makers’ demand for press-hardened steel sheet to grow 36%.
Steel has always been cheaper and stronger than aluminum. But conventional steel is heavy. Many car makers seeking to comply with tougher fuel-economy requirements have shifted in recent years to aluminum and other light materials such as carbon fiber. Now, steelmakers have figured out how to make steel lighter without compromising its strength or versatility.
“Everything is moving to thinner and lighter,” said Mark Bula, chief commercial officer at Big River Steel. a mill that opened in Arkansas last year. “The steel industry is moving that way as well.” On next year’s Audi A8, steel will make up 40% of the metal in the passenger compartment frame, up from 8% eight years ago.
By 2025, the amount of lightweight, high-strength steel in a car or light truck in North America is projected to rise to an average of 483 pounds, 76% above the 2015 average, according to industry consultancy Ducker Worldwide.
ArcelorMittal NV expects auto makers’ global demand for press-hardened steel sheet, which is strong and malleable for complex stamped parts, to grow 36% by 2020 to 3.7 million metric tons.
The company, the world’s largest steelmaker, began producing a new generation of super-strong steel at its mill in Calvert, Ala., this year.
And it plans to open a plant in Detroit late this year—the third of its kind in the U.S.—to weld and heat treat multiple pieces of lightweight steel of varying strength grades and thicknesses into a single sheet.
Sheets from these plants are stamped into large components, such as door frames, that feature some sections with extra-strong steel and others with steel that has less strength but is easier to bend. The 2017 Chrysler Pacifica’s two front door frames are each made of five pieces of steel with three different thicknesses. The door frames shaved 22 pounds off the vehicle, Fiat Chrysler said.
Aluminum remains in wide use with auto manufacturers looking to reduce a vehicle’s weight. Even as lighter steel gains popularity, aluminum is expected to continue replacing heavier steel varieties.
Aluminum content in cars and light trucks in North America is expected to reach an average of 520 pounds in 2025, a 31% increase from 2015, according to Ducker Worldwide. More than two thirds of closure components, such as hoods and trunk lids, on light vehicles are expected to be aluminum by 2020, double from 2016.
“High-strength steel has some inherent properties that are tough to escape from. It’s three times heavier” than aluminum, said Svein Richard Brandtzaeg, chief executive of Norwegian aluminum producer Norsk Hydro ASA. Aluminum’s penetration into the auto industry is experiencing some growing pains.
Auto makers in Japan are scrambling to check the safety of their aluminum components after one of Japan’s biggest aluminum suppliers, Kobe Steel Ltd., last week disclosed that quality control paperwork for auto customers had been doctored.
—Chester Dawson contributed to this article.
Average amount of lightweight, high-strength steel used per light vehicle in North America
BY BOB TITA