| We've grown up hearing about stainless steel our | | | | have high molybdenum contents and nitrogen |
| whole lives. But how many people actually know | | | | additions, as well as higher nickel content. Because |
| what it really is? Let's take a look at the process | | | | of these additions, they have a tremendous |
| of making steel stainless and some of its general | | | | resistance to chloride pitting and crevice corrosion. |
| applications. | | | | Other types of stainless steel include martenistic, |
| English metallurgist Harry Brearley invented | | | | ferritic and duplex, all of which have different |
| stainless steel in 1912 while he was researching | | | | compositions and strengths suited to various |
| alloys to protect cannons from erosion. The first | | | | applications. |
| commercial production of stainless steel occurred | | | | When its composition is 18 percent manganese |
| in August 1913. A few years later, stainless steel | | | | and 10 percent nickel, it is often referred to as 18 |
| played a key role in building valves for aircraft | | | | 10 stainless steel, which is often used in |
| engines during World War I. By the 1920's, people | | | | high-quality flatware. There are many different |
| were finding myriad uses for stainless steel in | | | | grades and surface finishes of stainless steel, |
| America. Most famously, the seven arches on top | | | | which makes the material very adaptable to |
| of the Chrysler Building in New York City were | | | | numerous applications. Look at the watch on your |
| clad in stainless steel in 1929. | | | | wrist. It's likely made from stainless steel. It is also |
| Chemically speaking, stainless steel is defined as | | | | to make airplanes, surgical appliances, building |
| an iron and carbon alloy with a minimum of 11.5 | | | | materials, cookware, cutlery, hardware, cars and |
| percent chromium content. Its name indicates | | | | jewelry. |
| some of its properties, because it does not stain | | | | Mill finishes can be applied to flat rolled stainless |
| or rust as easily as ordinary steel. It is also | | | | steel with the use of mechanical abrasives and |
| sometimes referred to as corrosion resistant | | | | the rollers themselves. After it is rolled to size and |
| steel. It should not be confused with galvanized | | | | annealed, oxidation is removed and the passivation |
| steel. Galvanized steel is dipped into zinc to | | | | layer is made on its surface. At this time, a final |
| prevent corrosion. Galvanized steel is created | | | | finish can be added to enhance the appearance of |
| when the zinc goes through a reaction with the | | | | the steel. |
| iron molecules. The most external layer is all zinc, | | | | For example, a sheet may have a matte finish to |
| but successive layers are a mixture of zinc and | | | | it, where the face of the material is abrasively |
| iron, with an interior of pure steel in galvanized | | | | polished leaving a clean but dull sheen to the |
| steel. | | | | surface. This is often desired where the material |
| Manganese is often found in many stainless steel | | | | will be used in a high visibility, high use location; the |
| compositions. Manganese preserves an austenitic | | | | surface will not show scratches and scars as |
| structure in the steel akin to nickel, and it is less | | | | readily as a highly polished finish. |
| expensive. Austenitic stainless steel makes up | | | | Stainless steel is available in both hot rolled steel |
| about 70 percent of the world's overall stainless | | | | sheets and cold rolled steel sheets, and it can also |
| steel production. Super austenitic stainless steels | | | | be obtained in plates, rolls, strips, foil and bars. |