Reigning Champ Steel Faces Lightweight Contenders

TRAVERSE CITY, MI – “Is steel dead?” United States Steel executive Bernhard Hoffmann asks about what has been the auto industry’s go-to material for more than a century.

He answers his rhetorical question by quoting from a Car magazine story pondering the future of the metal.

“The day of the passenger car made primarily of steel and iron is on the wane,” the article proclaimed – in 1953.

But steel still is going strong, in more ways than one, says Hoffmann, U.S. Steel’s vice president-engineering and product development for automotive solutions.

It is the auto industry’s material of choice, but others – notably aluminum – are elbowing in.

Hoffmann and Tom Boney of Novelis, an aluminum supplier, make their respective business cases during a session entitled “Manufactured Materials of the Future” at the CAR Management Briefing Seminars here.

A third of its global business is automotive, and Novelis (formerly Alcan) is “aggressively investing” in that segment and seeing “dramatic growth,” says Boney, Novelis North America’s vice president and general manager-automotive value stream.

As an automotive material, aluminum has a friend in federal government mandates that call for the industry to attain an average fleet fuel economy of 54.5 mpg (4.3 L/100 km) by 2025.

One way to do that is to use lighter materials, such as aluminum (more expensive than steel) and carbon-fiber composites (more expensive than aluminum).

“Our strategy was that as fuel-economy requirements strengthened, we would pursue (the use of aluminum in vehicles) aggressively,” Boney says. “More vehicles are moving towards multi-material construction to meet consumer demands and regulators’ pressure.

“Aluminum is recognized as a key material deployed by OEMs to meet the 2025 (fuel-economy) objectives. Mass reduction will play a key role.”

But Boney acknowledges reduced weight won’t play the only part in the auto industry’s quest for improved fuel economy, nor will aluminum become the only lightweight material used to help get there.

The current-generation Ford F-150 pickup is the current poster child for aluminum use. Its body and bed are aluminum. The upcoming Ford Super Duty is following suit. Increased use of aluminum also is in the Cadillac CT6 and the Mercedes-Benz C-Class. Audi and Jaguar were among the earliest adopters when it comes to wider use of the material.

“There are going to be a lot more mixed-material solutions,” Boney says.

'Magical Metal'

And one of those lightweight problem-solvers will be steel, Hoffmann says, referring not to the heavy metal of the past but to modern advanced high-strength steel he touts as light, safe, low-cost and 66% stronger than conventional steel.

So-called AHSS “is a magical metal,” he says while also heralding the benefits and prospects of ultra-advanced high-strength steel.

“The auto industry is balancing cost with performance,” Hoffmann says. “That’s why it is going to multi-material use.

“A lot of underbodies are going to steel. For aluminum, hoods and fenders make sense. It depends on what you are trying to do,” he adds.

“And it depends on the vehicle segment,” Hoffmann says, citing pickup trucks as candidates for possible weight-reduction plans.

Boney says: “This dialogue is healthy. There’s no holistic paint brush that will make a vehicle all-aluminum, all-steel or all-anything else.”

Adhering and affixing different metals to each other is on the work list of Dow and Kuka.

“We were a major contributor to the F-150 from a bonding perspective,” says Kurt Krier, Dow Automotive’s global business director. “Composite materials require more time, and we at Dow are working on it.

“But there is a greater use of structural adhesives. The industry and government (are) pushing that. It makes sense to use mixed composites in roofs and pillars, but it takes time to bring value up.”

Kuka, best known for robotics, is using advanced ways to join automotive materials. Those methods include laser welding and self-piercing rivets, says Peter Busuttil, Kuka Systems North America’s technology director. “We’re seeing a lot more material diversification.”

Asked to name barriers aluminum faces in the auto industry, Boney says: “One is capacity. More investment is required, considering demand. Our partners need to invest in capacity.

“A second barrier is that we’re the new guy in town. Even though aluminum is in 180 vehicles, the industry is dominated by steel.”

Asked the same question, Hoffmann says: “Our biggest challenge is getting out of our own way. We need to stop saying, ‘Steel is here, so keep using it.’” Instead, he says, the steel industry needs to “push the envelope with new technologies.”

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