Born Again

Just three years old, the Great Designs in Steel Seminar is pushing capacity limits at its current home, and may be looking for a new location next year.

More than 1,200 attendees — up from 750 in 2003 and 450 in 2002 — were in Livonia, MI, this year for the symposium, which is hosted by the American Iron and Steel Institute's (AISI's) Automotive Applications Committee. Sessions were standing room only.

Clearly, steel is enjoying a rebirth. For years, it struggled with a low-tech image as engineers and the media were enthralled with aluminum, plastics, magnesium and other so-called exotic materials.

With new grades and processes that enable it to be fabricated into stronger, lighter structures, steel is back at the technological forefront. Even after decades of progress made by other materials, steel still dominates automotive architectures. With the latest developments, it will be even harder to displace from future applications for one simple reason: despite the current furor over rising prices, steel still is far less costly than alternative materials.

General Motors Corp. says its use of advanced high-strength steels (AHSS) will increase from less than 11,020 tons (9,997 metric t) in 2004 to more than 132,200 tons (119,929 t) in 2010.

The steel industry began marketing AHSS to the auto industry in the late 1990s. However, the introduction of AHSS has been somewhat sluggish as auto makers learn the metallurgy and processing techniques of the new steel grades.

“The growth of high-strength steels company by company has been rather dramatic, at least by forecast,” Ron Krupitzer, AISI director-automotive applications, tells Ward's.

“But now the actual assignment of high-strength steels for each new model year has been increasing,” he says. “Some of the more aggressive projections show 60% of the mass of these vehicles will be high-strength steels in 2006-2008. Conservatively I would say 40% of the vehicles will be (high-strength steels).”

AHSS are lighter and stronger than conventional steels, such as low carbon, bake hardenable and high strength low alloy. Formability also is improved. OEMs typically use AHSS for hood, doors, fenders and structural beams.

Curt Horvath, GM development engineer-Body Structures and Closures Group, says the factors driving up use of AHSS are improved crash worthiness and weight reduction. He predicts use of conventional low carbon steel in a typical GM auto body structure will decline from 78% in the early 1990s to 11% in “the near future.” In the same time frame, use of an AHSS called “dual phase” will increase from 0% to 35%.

GM has formed an AHSS task force consisting of 10-15 engineers, who have been given the responsibility of implementing AHSS into product programs. “The success of the team will be noticed in the future in new vehicle architectures,” says Horvath. “The reality is, with our product lifecycles, the use of high-strength steels just cannot occur overnight or even in a year or two.”

GM's Epsilon midsize car platform, which is the basis for the Chevy Malibu and Malibu Maxx and Saab 9-3, represents GM's most significant AHSS project to date, including the auto maker's first use of dual phase steel in a welded body structure.

In 2005, “variants” off the Epsilon program will begin to slightly drive up GM's use of AHSS, Horvath says. “Moving into 2006-2008, you'll see our (AHSS) volumes increasing appreciably,” he adds.

The Great Designs in Steel Seminar also included the results of a public-private project that reduced the weight of an existing SUV frame by 23% by using new analytical tools and advanced high-strength steels.

An initiative of the U.S. Dept. of Energy, Auto/Steel Parternship members, Tier 1 frame suppliers, Altair Engineering and Oxford Automotive, the Lightweight SUV Frame Project Team reduced the weight of the '97-'02 Ford Expedition/Lincoln Navigator frame while maintaining structural performance. The only major components that would require modification in the new frame configuration are the fuel tank and exhaust system.

The improvements are achieved with a cost increase of $0.31 per pound, making it a good value by most standards.