Stainless structures: PNGV Supercar highlights qualities of stainlesssteel

If the Partnership for a New Generation of Vehicles (PNGV) Supercar project is any indication of the future of automobiles, then "light" is the key word and stainless steel is one material to watch.

Technology developed for the project includes a lightweight stainless steel vehicle structure designed by Armco Inc. and Autokinetics Inc.

Although it's often passed up in favor of other steel products for automotive structures, the PNGV concept gives stainless a chance to prove it can handle more than only exhaust systems, windshield wipers and shiny bumpers.

The material could use a boost. Although industry watchers estimate a typical family vehicle contains about 46.5 lbs. (21.1 kg) of stainless steel, use of the material has risen only 1.5 lbs. (0.7 kg) since 1994. During the same period, usage of both regular sheet, high- and medium-strength steel has grown between 10 and 20 lbs. (4.5 to 9 kg).

"People have concluded in their own minds that stainless steel is not in the running," says Bruce Emmons, Autokinetics president and the structure's inventor. "It is perceived as heavy and expensive. In reality, neither of those perceptions is true, if it is used correctly."

It may not be overlooked for long. The PNGV project, with a goal to create an 80-mpg (2.9L/100 km), family-sized car by 2004, gives stainless and Mr. Emmons' design a stage to show off its strength and lightweight properties.

The stainless steel structure may fit the project's goals perfectly because it has the potential to reduce body mass by 40% to 50% and even increase stiffness over traditional unibody construction, he says.

Unlike many innovations, cost will not be a major hurdle for the frame. The modular manufacturing uses cold-rolled stainless steel to form channels, welded to thin-wall cast joints, explains Autokinetics. The process integrates easily with computer-aided engineering applications, and eliminates a fifth of traditional manufacturing tools.

The cost of the raw material will not pose a problem either, says Joe Douthett, Armco's automotive market and product manager. Overall, he says, estimates show it will actually cost less than conventional steel structures.