Weathering steel, often referred to by the brand name COR-TEN, is characterized by its unique alloy composition, which leads to the formation of a stable, self-protecting rust layer when exposed to the atmosphere. This patina, composed primarily of iron oxides, inhibits further corrosion by forming a barrier against moisture and oxygen. For example, the characteristic reddish-brown hue seen on many outdoor sculptures and architectural facades is a direct result of this protective oxidation process.
The inherent durability and low maintenance requirements of this type of steel contribute to its widespread use in a variety of applications, from bridge construction and shipping containers to artistic installations and architectural cladding. Its longevity reduces life-cycle costs, while the distinctive aesthetic offers an appealing alternative to traditional painted steel. Historically, weathering steels gained prominence in the mid-20th century, finding early applications in railroad hopper cars due to their resistance to abrasion and atmospheric corrosion.