Full definition
An iron-based alloy containing a minimum of 10.5% chromium (Cr) that forms a passive oxide layer providing corrosion resistance far superior to carbon steel. Major grades for industrial applications: 304 (18Cr-8Ni, most widely used general-purpose grade, food equipment, chemical vessels), 316 (16Cr-10Ni-2Mo, superior resistance to chlorides and acids, marine/chemical/pharmaceutical environments), 316L (low carbon, weldable without sensitization), 420 (13Cr, martensitic, hardenable to 50 HRC, for cutlery and tools), 2205 duplex (22Cr-5Ni-3Mo, high strength + corrosion resistance for pipelines and pressure vessels). Yield strengths: 205 MPa (304 annealed) to 450+ MPa (duplex). Per ASTM A240 (plate), A312 (pipe), A276 (bar). Passivation per ASTM A967 recommended after fabrication. Used in food processing, pharmaceutical, chemical plants, marine environments, medical devices, and architectural applications where corrosion resistance is essential.