High-strength steel (HSS) and aluminum applications in auto
body designs have reached all-time highs, with increasingly
strict government regulations driving the need for better fuel
economy and lower carbon dioxide emissions-and further gains
are anticipated, including in mixed applications.
The decline in curb weight from 2004 to 2009 was the largest
in nearly 30 years, according to a recent study by Troy,
Mich.-based Ducker Worldwide LLC. Over the past two years
alone, an average of more than 114 pounds of mild-strength
steel was replaced in each new vehicle by HSS and aluminum and
through a shift to different body structures.
"There's not one car company that we've come across that
doesn't make use of increasing amounts of high-strength steel,"
said Ron Krupitzer, vice president of automotive applications
for the American Iron and Steel Institute's Steel Market
Advanced high-strength steels (AHSS) now account for nearly
15 percent of all steel in new vehicles compared with 10
percent in 2007, making it the fastest-growing automotive
material, according to the AISI.
Krupitzer noted that flat-rolled and other steel products
still accounted for more than half the curb weight of 2009
vehicles. "Steel is not only the existing material in a
vehicle, but it could very well be transformed to the new
products that have completely different performance standards,"
For instance, the family of AHSS that the auto industry uses
has gone from a 600-megapascal (MPa) tensile strength level to
1,000 MPa, according to Roger Heimbuch, executive director of
the Southfield, Mich.-based Auto/Steel Partnership. And the
associated cost is minimal because less material is required as
automakers develop smaller vehicles, he said.
New HSS products represent "the fastest-growing material in
the car, by far, because it is a cost-effective solution to
mass reduction," Heimbuch said, adding that a new generation of
AHSS will be coming to market within the next couple of
Heimbuch noted that the so-called body-in-white part of
vehicle assembly-the stage in which the car body sheet metal is
assembled-still focuses on traditional steel use. "It's the
hang-on components-doors, deck lids-that have been the parts
that have swung between materials," he said.
Meanwhile, aluminum continues to see greater market share in
vehicles. Aluminum accounted for an all-time high of 8.6
percent of average curb weight in 2009 vehicles, according to
the Council for Automotive Research, with more of the material
being used in hoods, engine blocks, control arms and suspension
links. Less aluminum was used in crossmembers-a structural
section of steel that is bolted across the underside of a
unibody motor vehicle-and in cradles, replaced by HSS in some
"Given the regulations that are being put in place all
around the world, aluminum is entering a golden age in
automotive," said Randall Scheps, marketing director at
Pittsburgh-based Alcoa Inc., pointing out that in addition to
hoods and deck lids, aluminum is on the cusp of high-volume
applications in door and roof panels.
Alcoa is heavily involved in the auto industry, supplying
everything from aluminum wheels for Detroit-based General
Motors Co.'s much-anticipated Chevrolet Volt electric car to
lightweight door assemblies for the Nissan GT-R sports sedan.
In the case of the GT-R, aluminum provides a weight savings of
30 to 35 percent, he said.
"We are really starting to hit the limit in how much weight
can be saved with a steel body design and I think the very next
logical step is aluminum," Scheps said. "We are seeing auto
executives all over the world coming to the realization that
aluminum is going to be the only way to get there."
Scheps pointed to a Ducker Worldwide report that predicts
aluminum content in North American vehicles will be greater
than 10 percent, or 376 pounds, of the anticipated 3,500-pound
curb weight by 2020, while worldwide aluminum content is
expected to grow to about 300 pounds per vehicle by 2020.
"We have never seen such a driving force in new projects and
applications as lightweighting in the market," said Laurent
Castor, general manager of automotive structures for Europe at
Alcan Automotive Structures, a division of Rio Tinto Alcan. The
company is a world leader in providing aluminum
crash-management systems, cockpit carriers and body-in-white
structures for the automotive industry.
Castor notices two significant trends when it comes to
aluminum content in vehicles: More high-end automakers who are
already leaders in aluminum use, like Germany's Audi AG, are
aggressively searching out new applications, even considering
all-aluminum vehicles; and aluminum is making significant
strides at all major automakers in areas of the vehicle where
it previously had only limited exposure, such as in bumpers,
crash-management systems, cockpit carriers and suspension
"Before, for example, aluminum crash-management systems
might be limited to a medium-sized car. Now, next-generation
small cars are getting the same treatment," Castor said. "We
have never seen such a move with such a dimension."
One of the biggest changes steel and aluminum producers
expect to face is the global auto industry's shift away from
full-frame large trucks and sport utility vehicles to lighter
unibody vehicle segments. In unibody designs, the floor, roof
and panels are welded together into one unit, thereby
eliminating the need for a separate frame. This helps to reduce
weight and improve fuel economy.
In North America, 77 percent of vehicles manufactured in
2009 used unibody frames, and this is expected to rise to more
than 80 percent by 2014, according to CSM Worldwide Inc.
For aluminum producers, this presents new challenges but
also added opportunities. While aluminum accounted for 8.6
percent of average vehicle curb weight in 2009, it made up only
1 percent, or less than 8 pounds, of unibody structures. A
Ducker Worldwide study expects that to increase to 4 percent,
or 26 pounds, by 2020, while HSS grades are expected to account
for more than 50 percent of light vehicles with unibody
"Aluminum is still very young in the auto industry, and
we're only now starting to see second-generation aluminum
alloys for automotive applications," said Castor, who also
expects to see an increase in mixed applications of aluminum
and steel. "The idea is always to find the right design for the
right material." DARCY KEITH
Jamie Zachary contributed to this story.