Stainless steel is a family of iron based alloys that must contain at least 10.5% chromium (Cr) by weight making it a low carbon (C) steel. It is this addition of chromium that gives the steel its unique corrosion resistant properties (i.e. “stainless”). This family is grouped into five branches which are identified by the alloying elements that affect their microstructure and for which each is named. Each of these branches has specific properties and a basic grade or type (i.e. “type-304”). In all, there are more that 60 grades of stainless steel.
The presence of chromium in the stainless alloy allows the formation of a rough, adherent, invisible, corrosion-resistant chromium oxide film on the steel surface. If damaged mechanically or chemically, this thin, transparent “passive” layer is capable or repairing itself providing that oxygen is present. The corrosion resistance and other useful properties (i.e. “weldability”) of the steel are enhanced by increased chromium (Cr) content and the addition of other elements such as molybdenum (Mo), nickel (Ni), and nitrogen (N).
Of the five branches that identify stainless steel alloys, we are particularly interested in two of these classes, the Ferritic and Austenitic. Within these two groups are the different types of stainless steel used to manufacture kitchen sinks and other related products in our industry. Ferritic (type-409, type-430) stainless steels contain 12-18% chromium (Cr) which classifies them as a stainless alloy but contain 0% molybdenum (Mo), nickel (Ni), and nitrogen (N) and are less expensive as compared to Austenitic stainless. In addition to more chromium (Cr) and less carbon (C), the Austenitic alloys also contain nickel (type-304, type-316) and molybdnum (type-316). For this, the Austenitic alloys are more corrosion resistant, harder (less likely to scratch or gouge) and are more weldable than Ferritic alloys. This is why Griffin Products, Inc. has chosen to produce its products using only the Austenitic alloys identified as type-304 and type-316 stainless steel.