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Auto still holds the most promise . . . but not without peril


By now, almost everyone who made the typical New Year's resolution has long since abandoned hope of getting lighter and stronger. Not so for the North American steel industry, which realized years ago that it must develop products that are lighter, stronger and more adaptable to the changing needs of a wide customer base.

Despite the global economic crisis, North American steel producers are still devoting millions of dollars to research into high-strength steels (HSS) as they attempt to regain market share lost to lighter metals like aluminum while at the same time making products stronger and safer for consumers.

"All of our divisions in Sweden and in the U.S. are pursuing high-strength steels in various products," said David Britten, president of SSAB North America Inc., Lisle, Ill., a unit of Sweden's Svenskt Stal AB (SSAB). "We see smaller niche opportunities in different market segments. We think there are more opportunities for growth in these markets."

Automakers who find themselves under increasingly stringent environmental regulations naturally are drawn to lighter, high-strength steels because they are more environmentally friendly. Less weight in the steel means higher payloads and improved mileage, and thus fewer trips and less vehicle wear and tear, among other environmental benefits.

"That's certainly part of it," Britten said. "People want to go green, if you will. People want to take advantage of those kinds of things. But there are financial benefits as well when it comes to life cycle. These products are stronger and last longer—they get nicked up, sure, but they don't have to be replaced as often."

SSAB has a long line of high-strength steel products it manufactures in Sweden and the United States, branded under names such as Amox, Docol, Domex, Hardox, Toolox and Weldox, each with different properties and chemistries that give them hardness, flexibility or other traits suited to various applications.

SSAB has added heat-treating operations to its plate mill in Mobile, Ala., and is learning to make some of those grades. The company is already experiencing success with customers who use the steels in such varied applications as crane booms, refuse trucks and some heavy equipment applications, Britten said.

"A lot of it is still in the developmental stage," he said. "We're learning to do a few of these things and seeing where they can be successful. A lot of customers are looking to do more with high-strength steels because of the environmental and financial benefits. It's an important niche and one where we see a lot of opportunity."

Carpenter Technology Corp., Wyomissing, Pa., also sees opportunity. The company has developed a new alloy known as Carpenter AerMet 340, which it says demonstrates high hardness, exceptional tensile strength, fracture toughness and yield strength. It has shown superior ductility to alloys of similar strength, the company said.

The new Carpenter grade, which can be used in a variety of automotive, racing, aerospace and defense applications, is already being used in applications in tubing, structural parts and components, driveshafts, springs, connecting rods and crank shafts.

Use of more high-strength steels regularly is associated with the U.S. automotive industry, where automakers and government regulations are seeking vehicles that are more fuel efficient but with improved crashworthiness.

"Advanced high-strength steels are in more and more demand," said Ron Hughes, manager of advanced engineering and product development at Severstal North America Inc., Dearborn, Mich. "The dual-phase steels and trip (transformation-induced plasticity) steels that we are using now not only are being employed to absorb energy in a crash, but to avoid penetration."

Hughes said that his company is the largest supplier of boron steels in North America. "We have been working with these kinds of steels for years," he said. "But in recent years, customers have been seeking better formability. Dual-phase steels were more formable than the high-strength low-alloy steels, and now the trip steels are more formable than dual phase. Now we're getting even more formability from heat stamping."

Environmentalists have applied pressure on the steel and automotive industries for the production of more environmentally friendly vehicles, Hughes said, but noted that the need for improved safety goes "hand in hand" with that. The U.S. government and the Insurance Institute for Highway Safety, for example, recently increased roof crush weight standards for vehicles. Government regulations are now moving to requiring roofs that can withstand 2½ times the vehicle weight, up from 1½ times previously, while insurance company standards are in the midst of increasing that requirement to four times their weight in rollover tests.

Jody Shaw, automotive marketing manager at the Troy, Mich., automotive unit of U.S. Steel Corp., Pittsburgh, said that although high-strength grades have been around for years, application opportunities are increasing. New vehicles now average about 150 pounds of high-strength steels apiece, up from only around 70 pounds as recently as 2007. "As we get more and more comfortable making these kinds of steels, we find more and more applications for them," he said. "Low-alloy steels have been very brittle. We are developing more high-strength steels that are not as brittle and, therefore, stronger and able to absorb energy better."

He believes that the development of high-strength steels, combined with the new, stiffer regulations for both crashworthiness and environmental friendliness, are opening the door to the use of more high-strength steels in automotive construction.

"I think you'll see it growing," he said. "We might be at somewhere between 10 and 15 percent usage in a body structure today. But I can see that with the way things are going it won't be too long before high-strength steels (comprise) 40 to 50 percent of a vehicle's body structure."

The North American steel industry is committed to expanding its work with automakers to develop more fuel-efficient vehicles that also will reduce dependence on foreign oil, the American Iron and Steel Institute, Washington, said. Research and development in high-strength steels is part of the plan.

Ronald Krupitzer, vice president of automotive applications for AISI's Steel Market Development Initiative, said the use of advanced high-strength steels offers significant benefits in cost, weight savings, improved safety, recyclability and life-cycle emissions for future vehicles. Recent work with automakers has demonstrated that high-strength steels available today can reduce a vehicle's structural weight by 25 percent.

The amount of steel in today's new vehicles represents about 60 percent of its total weight, he said. Research funded by the National Science Foundation and the U.S. Energy Department is under way at the university level to develop future steels that promise additional savings. The future grades should be available for vehicles built around 2020, when the 35-mile-per-gallon standard is expected to be in effect.

In addition to mass savings, steel offers low total emissions associated with manufacturing and driving vehicles, Krupitzer added. This is measured by life-cycle assessment, an established method of accounting for all the emissions associated with products like automobiles. The relatively low emissions and energy content of steels, and their high recyclability compared with other automotive structural materials, offer the cleanest environmental solutions to future vehicles. SCOTT ROBERTSON

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