Stainless steels were developed just after the turn of the century when it was discovered that the addition of chromium to iron created an alloy that resisted corrosion (rusting). This was achieved by the formation of an invisible chromium-rich oxide surface film. Over the years, it was found that particular characteristics could be improved by the addition of other elements such as nickel, molybdenum, copper, titanium, aluminum, silicone, niobium, nitrogen, sulfur, and selenium.
In the early 1900's, austenitic stainless steels were introduced. They offered excellent corrosion resistance and good high temperature strength. This material was designated "18-8" because the alloy contained 18-20% chromium and 8-10% nickel.
18-8 is the most widely used stainless steel today, and is the basic 302 or 304 austenitic stainless steel used at Edstrom Industries. Edstrom Industries uses 304 stainless steel to manufacture products that will not be exposed to corrosive environments.
Depending upon the desired alloy characteristics, elements are added or subtracted to 304 stainless steel.
The figure below provides a map of the compositional and property linkages to the family of stainless steel alloy.
The table below provides a reference to the composition of austenitic grades of stainless steel.
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