AK STEEL CORPORATION, Plaintiff, and Allegheny Ludlum Corporation and North American Stainless, Plaintiffs-Appellants, v. UNITED STATES, Defendant-Appellee, and Outokumpu Mexinox S.A. de C.V. (formerly known as Thyssenkrupp Mexinox S.A. de C.V.) and Mexinox USA, Inc., Defendants-Appellees