Automotive materials were a controversial topic in 2005, as prices soared in almost every sector of the industry compared with 2004.

Several major component suppliers, including Collins & Aikman Corp., Tower Automotive Inc. and Delphi Corp., filed for bankruptcy in 2005 citing raw material price increases as major contributing factors to their financial woes.

At the end of the year, little relief was in sight.

Since 2003, steel prices had climbed more than 150%. Hot-rolled coil prices – a benchmark for pricing – reached a record high of $756 per ton in September 2004 and averaged $744 per ton in 2005.

According to Roland Berger Strategy Consultants, the spike in prices was caused by several factors, including increased consumption by China and India, recent consolidation within the U.S. steel industry and continued growth in demand for steel in the U.S.

Over the past decade, China’s consumption of steel doubled, and it accounted for 30% of global demand in 2005, according to Roland Berger.

Steel remained the most used material by far in automobile production in 2005, but the industry’s pursuit of improved performance, safety and fuel economy led to a number of high-profile applications for alternative, lightweight materials, such as aluminum, composites and advanced plastics.

Aluminum Made Gains

For aluminum, one of the most significant applications in 2005 was Dana Corp.’s 285-lb. (129-kg), all-aluminum spaceframe chassis for the ’06 Chevrolet Corvette ZO6.

Developed in conjunction with Alcoa Inc., the ZO6’s frame was identical to the standard Corvette’s steel unit, yet weighed 136 lbs. (62 kg) less.

The assembly produced little, if any, profit for Dana, but company officials hoped the Z06 program would provide a foundation for profitable production of aluminum frames and chassis components in the future.

The weight savings, along with the use of other technologies such as an all-aluminum 7L V-8 engine, contributed to the ’06 ZO6 being the fastest production car ever released by General Motors Corp. and one of the lightest vehicles in the 500-plus-hp class.

However, aluminum was approximately twice as expensive as steel, which limited its use to niche vehicles such as the ZO6 and to high-end luxury cars, such as the aluminum-intensive Audi A8 and Jaguar XJ and the new ’07 XK.

In addition, aluminum also can improve safety, according to a safety study released by The Aluminum Assn. Inc. (AAI). The study concludes that injuries in crashes involving SUVs and other large vehicles could be reduced by up to 26% through the more liberal usage of aluminum in vehicle crumple zones and structural elements.

The implications of the study were timely in 2005, as gas prices climbed to near-record levels and a new wave of SUV safety concerns, primarily roof crush strength and SUV-to-smaller vehicle collisions, emerged from consumers and vehicle safety advocates.

AAI released the study before the National Highway Traffic Safety Admin.’s proposed restructuring of the corporate average fuel economy program scheduled for 2006.

“Depending on the specific approach pursued, NHTSA’s forthcoming proposal to restructure the CAFE program for SUVs, pickups and minivans could inadvertently create disincentives for use of innovative tools, technologies and lightweight materials by auto makers,” says Tom Gannon, chairman of AAI’s auto and light-truck group.

“Our goal is to ensure no artificial barriers are created that could potentially take innovative solutions linked to high-strength, lightweight materials out of the hands of the car makers,” he added.

North American vehicles contained about 280 lbs. (127 kg) of aluminum in 2005. That figure was expected to rise 2.5%-3.5% annually, with aluminum ultimately replacing iron as the second most-used material in automotive production by 2008, Gannon said.

Magnesium Made a Comeback

Magnesium, a strong metal substantially lighter than aluminum, also gained prominence in 2005 as auto makers strived to reduce the weight of increasingly complex vehicle designs.

The use of the material was not new. It was used in several high-volume applications dating back to the 1950s and 1960s, including the engine block for the original Volkswagen Beetle.

However, the development of new alloys and manufacturing processes, aimed at improving heat-resistance, allowed magnesium to garner more attention from engineers seeking to reduce the weight of modern vehicles.

One of the most notable applications for the material was BMW AG’s use of a hybrid magnesium/aluminum engine block for its new inline-6-cyl. engine. It debuted in 2004 on some European versions of the 6-Series coupe and was the standard engine on the auto maker’s all-new 3-Series released in 2005.

The magnesium block featured aluminum cylinder liners for better durability and was approximately 25% lighter than a comparable all-aluminum unit.

Other mainstream applications of the metal included the engine cradle in the Corvette ZO6 and the transmission case for DaimlerChrysler AG’s new 7-speed automatic, which was being adopted throughout the auto maker’s Mercedes-Benz luxury car and truck lineup.

In 2005, new vehicles contained an average of about 10 lbs. (4.5 kg) of magnesium, up from approximately 3 lbs. (1.4 kg) in the 1970s, said Norwegian magnesium supplier Hydro Magnesium.

In addition, developments in magnesium production yielded new versions of the lightweight alloy, such as AM-lite, developed by Australia’s Advanced Magnesium Technologies (AMT) and the CAST Cooperative Research Center.

AM-lite is cheaper and easier to cast than conventional magnesium alloys and has a higher-quality decorative finish, including the ability to be electroplated – a first for the material. It also is stronger and more rigid than plastics, conducts heat and provides electromagnetic shielding, AMT said.

Composites, Plastics, Made Inroads

Where weight savings were critical to a vehicle’s success, automotive engineers increased their focus in 2005 on the benefits of carbon fiber and composite structures.

Here again, GM’s new Corvette ZO6 served as a showcase of the industry’s push to adopt alternative, lightweight materials.

For the ZO6, GM used polyester and carbon fiber-reinforced balsa wood floorboards, supplied by Molded Fiber Glass Corp., to boost rigidity and reduce weight 30% compared with the fiberglass-reinforced units in the standard Corvette.

Although the reduction in mass accounted for only about 6 lbs. (2.7 kg) of the vehicle’s weight, it had a profound effect on the performance and agility of the ZO6 due to its location at the sports car’s crucial center of gravity.

The lightweight composite also was used for the ZO6’s front fenders, in an effort to further reduce weight and create an ideal 50-50 front-rear weight balance.

Other mainstream applications for the material included the roof structure of BMW’s M6 coupe and the oversized spoilers found on the Subaru Impreza STI and Mitsubishi Lancer Evolution sports sedans.

Nissan Motor Co. Ltd. also used composite liftback hatches, supplied by Quadrant Plastics Composites AG, for its Murano, Stagea (Japan market) and Infiniti FX vehicles. The auto maker said the 51-lb. (23-kg) Murano cross/utility vehicle hatch weighed 17% less than a steel unit.

Despite their benefits in niche vehicles, companies such as Lotus Engineering plc, renowned for its lightweight sports-car development, believed improved production methods would make composite vehicle structures more practical on a greater scale.

Lotus’ Ecolite front-end structure, developed with Jacob Composite GmbH, used new thermoforming and joining techniques, which the company expected to be cost-effective up to about 30,000 units annually, an increase from the 10,000-unit level.

Jason Rowe, Lotus chief material engineer, said the structure could weigh up to 30% less and provide the same crash protection in less space than a comparable steel unit.

Furthermore, Ashland Chemical Co. was working to reduce the bonding time for composite parts and make a business case for a composite decklid at volumes up to 120,000 units per year.

Conventional Plastics: More Innovative, Expensive

Like steel and aluminum, plastics are an integral part of modern vehicle construction. But the rising cost of oil also was affecting raw material prices for plastic resins, making it more difficult to integrate new plastic innovations in future vehicles.

Despite these challenges, several designs garnered significant awards in 2005 from the Society of Plastic Engineers.

Notable winners of SPE’s 35th Annual Automotive Innovation Awards included the 8.5-cu.-ft. (0.2-cu.-m) composite, in-bed trunk of the ’06 Honda Ridgeline pickup.

Integrated into the vehicle’s unibody structure and supplied by Meridian Automotive Systems, the technology featured a 1,100-lb. (499-kg) carrying capacity and had better impact strength and corrosion resistance than steel.

Dura Automotive Systems won an award for the all-plastic power window regulator used in the ’06 Chrysler PT Cruiser. The conversion from steel to plastic reduced part count from 21 to 13, cut the number of attachment points to the vehicle from five to two and reduced the number of assembly line workers.

Autoliv Inc. also received accolades for its molded-in-color thermoplastic olefin airbag cover in the ’06 Buick Lucerne (20% weight savings and 45%-65% cost savings over conventional painted covers), while AKSYS GmbH won an award for its glass-mat-reinforced composite pedestrian-protection beam found in the front bumper of the ’04 Volkswagen Golf.

The composite beam minimizes injuries to pedestrians and offered a 30% weight savings, 50% material cost savings and 15% tooling cost savings vs. steel.