English metallurgist Harry Brearley invented stainless steel in 1912 while he was researching alloys to protect cannons from erosion. The first commercial production of stainless steel occurred in August 1913. A few years later, stainless steel played a key role in building valves for aircraft engines during World War I. By the 1920's, people were finding myriad uses for stainless steel in America. Most famously, the seven arches on top of the Chrysler Building in New York City were clad in stainless steel in 1929.



Chemically speaking, stainless steel is defined as an iron and carbon alloy with a minimum of 11.5 percent chromium content. Its name indicates some of its properties, because it does not stain or rust as easily as ordinary steel. It is also sometimes referred to as corrosion resistant steel. It should not be confused with galvanized steel. Galvanized steel is dipped into zinc to prevent corrosion. Galvanized steel is created when the zinc goes through a reaction with the iron molecules. The most external layer is all zinc, but successive layers are a mixture of zinc and iron, with an interior of pure steel in galvanized steel.

Manganese is often found in many stainless steel compositions. Manganese preserves an austenitic structure in the steel akin to nickel, and it is less expensive. Austenitic stainless steel makes up about 70 percent of the world's overall stainless steel production. Super austenitic stainless steels have high molybdenum contents and nitrogen additions, as well as higher nickel content. Because of these additions, they have a tremendous resistance to chloride pitting and crevice corrosion. Other types of stainless steel include martenistic, ferritic and duplex, all of which have different compositions and strengths suited to various applications.

When its composition is 18 percent manganese and 10 percent nickel, it is often referred to as 18/10 stainless steel, which is often used in high-quality flatware. There are many different grades and surface finishes of stainless steel, which makes the material very adaptable to numerous applications. Look at the watch on your wrist. It's likely made from stainless steel. It is also to make airplanes, surgical appliances, building materials, cookware, cutlery, hardware, cars and jewelry.

Mill finishes can be applied to flat rolled stainless steel with the use of mechanical abrasives and the rollers themselves. After it is rolled to size and annealed, oxidation is removed and the passivation layer is made on its surface. At this time, a final finish can be added to enhance the appearance of the steel.

For example, a sheet may have a matte finish to it, where the face of the material is abrasively polished leaving a clean but dull sheen to the surface. This is often desired where the material will be used in a high visibility, high use location; the surface will not show scratches and scars as readily as a highly polished finish.

Stainless steel is available in both hot rolled steel sheets and cold rolled steel sheets, and it can also be obtained in plates, rolls, strips, foil and bars.