Why are bridges and power lines covered with a thick layer of rust in the USA? (5 photos)
In some photographs from American life, eyes can get caught very strange metalwork, completely covered good layer of rust. Most often these are fences, bridges or pillars of lines power lines. What is it: the result of a corruption conspiracy builders and authorities, saving paint or banal spit? A maybe rusty metal structures - is it something else? 
Actually see the metal structures, completely covered rust, can be seen not only in the USA. And of course, as one could guess that fences, poles and supports are rusting for a reason. In in any case, if you have a metal structure in front of you, which is covered completely rusty. In this case, it was intended to be so, because before you a Corten steel product. 
Corten Steel Oxidation Process
The name of Corten steel comes from the English abbreviations "COR-TEN steel", which in turn stands for as "CORrosion TENsile", which literally means only "corrosion resistant". The name may seem strange, but this is the point! Corten is an alloy steel that protected from rust with "rust". How is this even possible? 
Corten steel was invented in the USA in the 1930s. American company U.S. Steel. This material is essentially alloy steel, but not the most common. As with the smelting of any other modern steels add certain alloying agents to corten additives. First of all, these are such classical elements as manganese, chrome, silicon, nickel. These components are available in almost any conventional alloy steel. But what is really not usual in corten is the presence of phosphorus in the alloy. Last in the majority ordinary steel is considered a harmful impurity! However, in corten, phosphorus at adding copper and the right amount of carbon leads to unexpected results... 
Due to the correct addition of phosphorus, alloy steel acquires resistance to atmospheric corrosion. Caught in the open air, corten begins to oxidize, resulting in material, a patina is formed - a copper film. Exactly uniform velvety layer of patina and looks like rust from the outside, while the copper film protects the metal surface from further oxidation and the formation of ordinary rust. Corten constructions are extremely practical due to the absence of the need to use traditional anti-corrosion measures, such as painting the material. And since corten steel "rusts" completely and evenly, it looks quite aesthetically. 
Of course, there are some "buts" that do not allow use corten everywhere. The copper patina that forms over miracle material, absolutely not friendly with sea air, saturated aggressive salts, as well as with the atmosphere in industrial areas where The air may also contain highly corrosive substances that can destroy copper plaque. Therefore, the use of corten is limited. geographically and economically. However, the material has received enough widely used in construction, bridge building, shipbuilding and even art.
