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U. S. Steel's New
Family of DUAL-TEN® Steels Will Help Make Automobiles Lighter, Safer
and More Fuel Efficient
TROY, Mich., United
States Steel LLC (NYSE: X)
has become the first American steelmaker to develop and produce
commercially a family of dual phase steels.
Marketed under the trademark
DUAL-TEN® steel the new steels have been engineered to meet the demands of
automakers for high-strength, light-weighting materials with improved
formability that will help them reduce vehicle weight and cost while
improving crash safety performance. U. S. Steel's DUAL-TEN®
590 steel is
currently in use by major automobile manufacturers in large production
volume automobiles, and other grades are being qualified and implemented
in the design of future vehicles. Traditional high-strength low alloy (HSLA)
steels depend on alloying for their strength. This strength, however,
comes at a cost to formability and severely restricts the flexibility of
automotive designers to create the complex automotive components
required for efficient lightweight designs.
Unlike HSLA steels,
DUAL-TEN® steels derive their strength from unique combinations of two crystalline
structures, ferrite and martensite, and have demonstrated advantages
over HSLA steels in formability and structural performance. At its
automotive center in Troy, Mich., U. S. Steel is demonstrating the
advantages of DUAL-TEN® steels through testing and computer
simulation. In a comparison with HSLA50, conventional steel with similar
yield strength, DUAL-TEN® 590 steel demonstrates improved performance in
deep draw and stretch forming stamping operations. Its superior
formability gives automobile designers greater design flexibility to
optimize component shape to carry loads more efficiently throughout an
automobile's structure. Studies of the fatigue performance of DUAL-TEN®
590 steel are currently under way, however, it is predicted to
have a 35 percent advantage over HSLA50. The inherent strength of
DUAL-TEN® steels is enhanced through rapid work hardening during the stamping
process, and again during the painting process when the steel becomes
bake hardened. These processes can increase steel strength as much as 80
percent over the virgin sheet.
U. S. Steel's
DUAL-TEN® steels offer
better crash performance over conventional steel due, in part, to the
added strength, but also because of its strain rate sensitivity, which
means the faster the steel is crushed, the more energy it can absorb. In
30 mph drop tests, DUAL-TEN® 590 steel has been shown to absorb 20 percent
more energy than HSLA50. This means that an automotive crash component
made of DUAL-TEN® steel will perform the same function using less
steel. "The demands on the automobile industry to continually
improve vehicle safety and fuel economy while reducing cost will be
achieved by innovative design, advanced material processing and advanced
materials," said John Peters, general manager of automotive for U.
S. Steel. "To help the auto industry meet these demands, U. S.
Steel's DUAL-TEN® steels provide a remarkable combination of
formability, strength, ductility, durability, strain-rate sensitivity
and strain hardening characteristics." "DUAL-TEN®
steels
can provide significant weight reduction with equivalent or improved
strength, durability, and crash performance," said Mike Juddo,
director of product technology at U. S. Steel's automotive center.
"These advanced automotive materials will play a dominant role in
the next decade of vehicle design, to meet the needs of our customers to
improve fuel economy and safety while reducing costs."
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