Stainless steels

Abstract

Stainless steels are more resistant to rusting and staining than plain carbon and low alloy steels. They may be defined as iron base alloys containing at least 10.5% chromium. They achieve their stainless characteristics through the formation of an invisible and adherent chromium -rich oxide surface film. This oxide forms and heals itself in the presence of oxygen. Other elements added to improve particular characteristics include nickel, molybdenum, copper, titanium, aluminum, silicon, niobium, nitrogen, sulfur, and selenium. Stainless steels are commonly divided into five groups: martensitic, ferritic, austenitic, duplex (ferritic-austenitic) and, precipitation-hardening.