High oxidation resistance in air at ambient temperature is normally achieved with additions of a minimum of 13% (by weight) chromium, and up to 26% is used for harsh environments. Stainless steels have higher resistance to oxidation (rust) and corrosion in many natural and man made environments however, it is important to select the correct type and grade of stainless steel for the particular application. This material is also called corrosion resistant steel when it is not detailed exactly to its alloy type and grade, particularly in the aviation industry. The name originates from the fact that stainless steel does not stain, corrode or rust as easily as ordinary steel. Stainless steel is defined as a ferrous alloy with a minimum of 10% chromium content. STRENGTH-TO-WEIGHT ADVANTAGE The work-hardening property of austenitic grades, that results in a significant strengthening of the material from cold-working alone, and the high strength duplex grades, allow reduced material thickness over conventional grades, therefor cost savings. HYGIENE The easy cleaning ability of stainless makes it the first choice for strict hygiene conditions, such as hospitals, kitchens, abattoirs and other food processing plants. FIRE AND HEAT RESISTANCE Special high chromium and nickel-alloyed grades resist scaling and retain strength at high temperatures. Benefits of Stainless Steel CORROSION RESISTANCE Lower alloyed grades resist corrosion in atmospheric and pure water environments, while high-alloyed grades can resist corrosion in most acids, alkaline solutions, and chlorine bearing environments, properties which are utilized in process plants. Each is identified by the alloying elements which affect their microstructure and for which each is named. However, the entire group can be divided into five classes. There are more than 60 grades of stainless steel. 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. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present. The chromium content of the steel allows the formation of a rough, adherent, invisible, corrosionresisting chromium oxide film on the steel surface. It is this addition of chromium that gives the steel its unique stainless, corrosion resisting properties. Stainless steel is essentially a low carbon steel which contains chromium at 10% or more by weight. However, over the total life of a project, stainless is often the best value option. Engineer, specifiers and designers often underestimate or overlook these values because of what is viewed as the higher initial cost of stainless steel. The many unique values provided by stainless steel make it a powerful candidate in materials selection.
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