Stainless steel can corrode if conditions are sufficiently severe. Like other corrosion-resistant alloys, though, it is significantly more corrosion resistant than basic carbon steels.
To be called a stainless steel, a grade must contain >10.5% chromium. This forms a protective passive layer on the surface when the steel is exposed to oxygen, which shields the underlying metal from corrosion. If that layer is physically damaged and cannot regenerate, corrosion will occur. Inclusions from the steelmaking process may reach the surface of a component, leaving a gap in the passive film where corrosion can initiate.
Component geometry can create particularly aggressive localised conditions, leading to crevice corrosion and then pitting corrosion. Ultimately, if the medium in contact with the steel is aggressive enough, for example concentrated reducing acids, or the temperature is elevated, corrosion will occur on almost any stainless steel.
What applications is stainless steel ideal for?
Stainless steel is particularly suited to exposed applications, marine environments and industrial settings where other metals would not survive, or where continued maintenance and replacement is not feasible.
In domestic applications or inland environments, stainless steel is unlikely to corrode if correctly specified and installed. In many of these applications its appearance is as desirable as its long-term performance.