ArcelorMittal won a revival of its patent-infringement case against AK Steel Corp. over a process to make steel stronger so it can be used in automobile manufacturing.
A trial judge erred in her interpretation of what an ArcelorMittal patent covered, the U.S. Court of Appeals for the Federal Circuit in Washington today said in an opinion posted on its website. The Federal Circuit said the judge should consider whether the patent was valid and infringed. It said she could consider ruling on the issue without need for a new trial.
The patent covers boron steel sheet used for “hot-stamping,” a process to rapidly heat the steel, form it into the appropriate shape and then quickly cooling it. That allows the steel to be thinner and lighter than steel produced by other processes while being just as strong.
A federal jury in Wilmington, Delaware, had said the patent was invalid and not infringed.
The case is ArcelorMittal France v. AK Steel Corp., 2011-1638, U.S. Court of Appeals for the Federal Circuit (Washington). The lower court case is ArcelorMittal France v. AK Steel Corp., 10CV50, U.S. District Court for the District of Delaware (Wilmington).