2205

2205 is a duplex stainless steel grade, known as UNS S32205 and commonly designated 1.4462 in Europe. It is engineered to combine high strength with excellent corrosion resistance in chloride-containing environments. The term duplex refers to its two-phase microstructure, a balanced mix of ferrite and austenite that improves performance over conventional austenitic grades.

Typical composition includes approximately 21–23% chromium, 4.5–6.5% nickel, 2.5–3.5% molybdenum, and nitrogen around 0.14–0.20%, with carbon limited to about 0.03%. The alloy forms a duplex microstructure with roughly equal ferrite and austenite phases, yielding a high-strength, tough material.

Yield strength is around 450 MPa and ultimate tensile strength about 650–750 MPa, depending on processing. Ductility remains adequate for many applications, and impact toughness is good at room temperature and below.

2205 offers very good resistance to pitting and crevice corrosion in chlorides, as well as general corrosion resistance. The presence of chromium, molybdenum and nitrogen enhances its performance in seawater and other aggressive environments.

It is weldable by common methods (MIG, TIG, stick) using appropriate filler metal, such as ER 2209. Controlling heat input is important to preserve the duplex structure; post-weld heat treatment is not required but may be used to relieve stresses.

Common applications include chemical processing equipment, oil and gas, desalination plants, and marine structures. Standards include ASTM A240/A240M and A182, with European designation 1.4462 (EN).