Mention the topic of weathering steel to a group of designers, and two things usually come to mind: COR-TEN and bridges. COR-TEN is a trade name developed by U.S. Steel to market weathering steel. And bridges— well—they’re the most common application for weathering
steel today. So what is this stuff? Weathering steel is a steel alloy containing quantities of copper, chromium, nickel, and other alloying elements that enhance corrosion resistance. When
the steel rusts under normal atmospheric conditions, it forms a protective patina that bonds with the surface of the steel. Over a relatively short period of time, the patina forms into an impervious layer that precludes further corrosion. Minor damage to the coating is self-healing. In its early stages, the coating is a reddishorange brown color. Over time, the coating thickens, the
texture becomes a bit rougher.