By Tony Whitney
Automakers experiment constantly with new materials with which to construct vehicles, but breakthroughs are rare. Automakers have remained faithful to steel and, now and again, aluminum, for building vehicle bodies. Of course, in the world of high-performance “supercars”, there are entire bodies built from expensive carbon fibre – the Mercedes-Benz McLaren SLR is perhaps the best known example. Various less costly composites are widely used by such makers as Saturn and Chevrolet (for the Corvette).
As far as aluminum goes, Audi chose this material for its flagship A8 sedan and the body of this car is welded together from light alloy sheet, diecast components and complex extrusions. Jaguar has moved extensively towards all-aluminum bodies and Land-Rover has always made wide use of the material. Honda’s NSX sports car has been built from aluminum for many years and most vehicles these days use aluminum for hoods and trunk lids.
But despite inroads by aluminum and other materials, it’s still steel that is used for the vast majority of new vehicle bodywork. Current steels are very different from their equivalents of years gone by. According to the North American Iron and Steel Institute, the steel used in our vehicles has never been stronger. It’s an interesting fact that 70 per cent of the steel used in automotive production today didn’t even exist just ten years ago. For five years now, steelmakers and automotive manufacturers have been working closely together to develop more advanced high-strength steels and more innovative applications. Steel auto components are more dent-resistant and up to 30 per cent stronger than they were ten years ago. According to the Iron and Steel Institute, goals for safety and fuel efficiency are being achieved without any increase in material costs.
The steel institute claims that the properties of steel – strength, strain rate, formability, manufacturability and response to heat treatment – are unmatched by any other material available to automakers.
As far as usage goes, steel has maintained an average of 55 per cent of the curb weight of a typical passenger car over the past 20 years. Although other materials have made inroads, the steelmakers believe that the new steels promise to continue this tradition.
As an example of costs, a current Chevrolet Malibu, which stickers at around $23,000, uses steel costing around $675 – a surprising material/MSRP ratio, given the amount of steel used in a vehicle like that.
On the environmental front, in 2003 more than 14.5-million tons of steel were recycled from automobiles in North America and recovery rates by recyclers are amazingly high. Recyclers reclaim as much steel from junked vehicles as automakers use in making new ones and virtually every scrap is recovered. Automobiles are among the most efficiently recycled consumer products on the planet and have been for decades. Steel is far easier to recover from junked vehicles than aluminum and composites – and simpler to render down and re-use for another generation of vehicles.
While your new vehicle uses a variety of materials for its bodywork, steel is likely to dominate for some time.