Alcoa Aluminum Shines in Sequel

The drive to make cars and trucks lighter and more fuel efficient is having a profound effect on materials development. Automotive engineers discussed progress with new dual-phase steels last month at a conference in Troy, MI.

Aluminum is not asleep at the wheel either. Alcoa is providing structural design, engineering and manufacturing expertise for the Chevrolet Sequel, which General Motors believes is the most technologically advanced vehicle ever built. It features a hydrogen fuel cell power system as well as drive-by-wire, in which traditional mechanical and hydraulic control systems are replaced with electronic control systems. GM is looking to high-tech aluminum to dramatically reduce body weight, showing that SUVs can survive in a global warming environment.

More than 300 aluminum structural components have been produced by Alcoa at its R&D center in Lower Burrell, PA for the bodies in white for the Sequel. Body in white refers to the car body before the motor, chassis and trim are added.

The work includes development of newly engineered aluminum sheet for stampings, high-integrity castings and complex, multi-hollow extrusions for body-in-white and chassis structures. Sheet was specially formulated for use in GM's forming process called "quick plastic," which is an advanced hot blow forming process developed by GM and the U.S. Department of Energy. The process increases the formability of special aluminum alloys, resulting in production of integrated net shape components. Because part count is reduced, aluminum may be able to replace steel at competitive costs. The net benefit is a 40 percent weight savings.

It's one of the key cards aluminum will play in its battle to increase market share in tomorrow's vehicles, and the Sequel is the test bed. Alcoa is also supplying large blanks for the Sequel's outer body panels, as well as cast front and rear sub-frames. As is the case with the new advanced steels, significant work is also required in areas such as assembly. Specific targets in the Sequel project are welding, self-piercing and blind rivets and adhesive bonding.

The Sequel was first shown by GM as a concept car two years ago, and a drivable prototype was announced last fall when GM said the car would be branded as a Chevy. The Sequel uses clean, renewable hydrogen as a fuel and emits only water vapor.

"Sequel fundamentally changes the DNA of today's automobiles ... exchanging an internal combustion engine, petroleum and mechanical systems for fuel cell propulsion, hydrogen and electrical systems," says Larry Burns, GM's vice president of R&D and strategic planning.

The Sequel is now more than just a for-show concept car for General Motors. It's a car the company intends to place into production. Considering financial, political and technical demands, it may be 10 years before you can actually drive one, however.