ArcelorMittal Sues Rivals for Infringing Steel Patent

ArcelorMittal, the world's largest steelmaker, has sued Russia's OAO Severstal and Japan's Nisshin Steel, alleging that they misappropriated its patent for automotive steel, Bloomberg News reports.

Because the complaint involves the American units of all three companies, the lawsuit was filed in U.S. federal court in Wilmington, Del.

ArcelorMittal sued West Chester, Ohio-based AK Steel Holding Corp. in that court last week about the same patent, which involves high-strength aluminum-boron steel used in stamped parts.

The Luxembourg-based company lost a similar patent claim against AK Steel and Severstal in federal court in Wilmington in 2010. Last month the U.S. Court of Appeals reaffirmed ArcelorMittal's patent.