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