Stainless steel is a corrosion resistant steel alloy with a minimum of 10% chromium. There are different grades and surface finishes of stainless steel produced to accommodate the environment in which the material will be implemented. Unlike carbon steel, stainless steel does not rust when exposed to air and moisture due to the sufficient amount of chromium present. The chromium creates an invisible passive film of chromium oxide that will not let oxygen attack the surface and prevents rusting of the iron base.
Also, when the surface is scratched this layer quickly reforms. This phenomenon is called passivation by materials scientists, and is seen in other metals, such as aluminium. When stainless steel parts such as nuts and bolts are forced together, the oxide layer can be scraped off causing the parts to weld together.
Stainless steel, also known as inox steel is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel .] It is also called corrosion-resistant steel or CRES when the alloy type and grade are not detailed, particularly in the aviation industry.