Used for many industrial, architectural, chemical and consumer applications for over half a century, stainless steel is essentially a low-carbon steel, which contains chromium at 10.5 percent or more by weight. It is this addition of chromium that gives the steel its unique stainless, corrosion-resisting and enhanced mechanical properties.
The chromium content of the steel allows the formation of a rough, adherent, invisible corrosion-resisting chromium oxide film on the steel surface. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present. The corrosion resistance and other useful properties of the steel are enhanced by increased chromium content and the addition of other elements such as molybdenum, nickel and nitrogen. Nickel also gives stainless steel a lustrous and brighter appearance which is less gray than steel that has no nickel.
Type 304 is the basic chromium-nickel austentic stainless steel and has been found suitable for the widest range of applications in all kinds of products and architectural work. As part of the 300 Series designation it is composed basically of 18 percent chromium and 8 percent nickel and is sometimes referred to as 18-8 stainless. It is nonmagnetic and cannot be hardened by heat treatment. It is readily available in a variety of forms. This type is easy to form and fabricate with excellent resistance to corrosion.
The many unique values provided by stainless steel make it a powerful candidate in materials selection. Engineers, specifiers and designers often underestimate or overlook these values because of what is viewed as the higher initial cost of stainless steel. However, over the total life of a project, stainless is often the best value option.