NEW YORK ArcelorMittal SAs petition for a rehearing on a patent infringement lawsuit has been denied by the U.S. Court of Appeals for the Federal Circuit, opening the door to allow defendants AK Steel Corp., Severstal Dearborn Inc. and Wheeling-Nisshin Inc. to continue selling aluminized boron steel products.
ArcelorMittal requested the rehearing in January. The case, first filed by ArcelorMittals French units in 2010, will be sent back to U.S. District Court in Delaware.
The district court previously ruled that there had been no infringement on a U.S. patent for boron steel sheet with an aluminum-based coating held by ArcelorMittal France and ArcelorMittal Atlantique et Lorraine. ArcelorMittal challenged that courts definition of the patent, which it said applied to steel sheet that was hot-rolled but not cold-rolled, and appealed the case to the U.S. Court of Appeals.
In November, the appeals court ruled that ArcelorMittals Usibor patent applies to cold-rolled steel for hot stamping and is not limited to hot-rolled steel, remanding the case to U.S. District Court under the new patent claim construction (amm.com, Dec. 3).
The appellate court did, however, uphold the district courts opinion that the patent applies only to aluminized boron steel products with a tensile strength above 1,500 megapascals (MPa), and that the defendants could continue to sell aluminized boron steel with a tensile strength less than 1,500 MPa.
AK Steels Ultralume product has a tensile strength of up to 1,500 MPa, so the product does not infringe upon the patent in regard to tensile strength, the courts agreed.
ArcelorMittal did not immediately respond to requests for comment, but a spokeswoman said in a statement last week that the company "intends to enforce its rights against any infringers."
West Chester, Ohio-based AK Steel and Dearborn, Mich.-based Severstal use aluminum-coated boron steel for automotive applications. Severstal said it has been selling the product for five years and using it in original equipment manufacturers lightweighting initiatives.
"AK Steel believes it will prevail again, and the entire patent will be invalidated," a spokesman for AK Steel told AMM in an e-mail.
"We are pleased with the U.S. courts decision to uphold our right to continue producing and selling cold-rolled aluminum boron steel for hot stamping while this patent infringement appeal process continues," Severstal vice president Martin Szymanski said in a statement.
Follansbee, W.Va.-based Wheeling-Nisshin did not respond to requests for comment.