Steel? Weathering Steel

What is steel? How is it used? Why is weathering steel - Corten a popular contemporary material? First of all, steel is what is known as an alloy, or a combination of two or more metallic elements. Humans have been developing alloyed metals for centuries with the aim of providing further strength or corrosion resistance. Steel is an alloy of iron and a small amount of carbon (about 2%). Historical records point to its first development in England in the 19th century, but it is widely believed that its full development occurred between the 1930s and 1970s. Steel is the most commonly used material for infrastructure and industrial construction in the world today.

Based on their chemical composition, steels are categorized into three main groups: carbon steels, low-alloyed steels, and high-alloyed steels. The main component of steel is iron, a metal that is not much harder than copper in its pure state. Adjusting the carbon content is the easiest way to change the mechanical properties of steel. Adding other alloying elements also permits tempering at higher temperatures, resulting in a steel with better ductility at the same hardness and strength. There are thousands of published, registered or standardized steel grades worldwide, all with different chemical compositions. All these different types of steel have many possible heat treatments, microstructures, cold forming conditions, shapes and surface finishes. A well-known example is the well known stainless steel.

Weathering steel, trademarked COR-TEN steel and Corten steel, is a mild steel alloy designed to eliminate the need for painting and to develop a stable rust-like appearance after several years of exposure to weather. It was first developed in the United States in 1933 by U.S. Steel. Weathering steels were the first and earliest of the six current categories of high-strength low-alloy steels. Weathering steels are considered to be the strongest, with atmospheric corrosion resistance 4 to 8 times that of ordinary mild steel. A unique characteristic of weathering steels is that, as a result of exposure to the outdoors, they develop a thin brown patina that differs in appearance, composition and structure from other types of patina. Over time, with constant exposure to cycles of wetting and drying, this patina turns orange and then reddish brown. After a year of exposure, especially in urban environments, the patina turns dark brown.