Weathering steel is a trademark name for a type of weathering steel known for its distinctive, rusted surfaces, used in architectural facades and sculpture, and integrated into landscape design. While U.S. Steel Corp. owns a trademark for the name Corten, the term is commonly used for all Corten Steel, a group of Steel alloys that develop a rust-like appearance over time. “When you buy corten steel today, it may or may not be corten steel,” said Branden Adams, a designer and manufacturer at BaDesign in Oakland, Calif.