Stainless Steel is a metallic alloy having iron as the base metal with significant amount of chromium addition. The carbon content of this steel is usually low and can go to a maximum of 1.2% carbon. Chromium content can greatly vary but in order to be a stainless-steel, a minimum chromium content must be 11% or greater. Due to significant chromium content, chromium atoms are able to disperse throughout the matrix and protect the surface by forming a thin passive layer of chromium oxide (Cr2O3). This Cr2O3 layer is grown through passivation to increase the thickness of the passive layer so that superior properties can be obtained. Being passive in nature, stainless steel coatings are a preferred industrial choice for many parts, machines and equipment. It not only offers corrosion protection, but also increases the durability of the part. The passive oxide coating makes stainless steels immune to most oxidation attacks depending on the application of use and the environmental factors involved. The selection criteria for stainless steel coatings is largely dependent on the application of use and the environmental factors associated with that application. Stainless steel coatings are an excellent and inexpensive choice when it comes to dry and oxygen accessible environments. In cases of high salinity and humidity, stainless steel coatings can be limiting. The addition of other alloying elements, such as molybdenum, to stainless steels can increase the corrosion resistance and improve protection against chloride environments and pitting attacks.
