Material number S32205: 2205
S32205 is the Unified Numbering System designation for 2205, ferritic-austenitic (duplex) stainless steel specified in ASTM A240.
What S32205 means
UNS numbers (ASTM E527 / SAE J1086) use a letter for the alloy family and five digits: G = AISI/SAE carbon and alloy steels (G41400 = 4140), S = stainless and heat-resisting steels (S30400 = 304), K = miscellaneous steels (K02600 = A36), T = tool steels, N = nickel alloys. The UNS number identifies a composition, not a product form or property level, so S32205 appears in several ASTM specifications (plate, bar, pipe) with different mechanical requirements.
2205 at a glance
2205 is the standard duplex stainless steel — the alloy most often specified when 316L is not strong or corrosion-resistant enough but super-duplex or nickel alloys are unnecessary. Its microstructure is roughly 50 % ferrite and 50 % austenite, which gives it about twice the yield strength of 316L (450 vs 205 MPa), a pitting resistance equivalent of 35 or more (316L: 24), excellent resistance to chloride stress-corrosion cracking, and good weldability in modern nitrogen-balanced heats. Two UNS numbers apply: S31803 (the original 1980s window) and S32205 (from 2000, guaranteeing Cr ≥ 22, Mo ≥ 3, N ≥ 0.14 and therefore PREN ≥ 35). Nearly all current production meets both and is dual-certified; specify S32205 for new work. ASTM A182 forgings are F51 (S31803) and F60 (S32205).
The high strength lets designers cut vessel and pipe wall thickness by 30–50 % versus austenitic steel, which is why 2205 dominates in chemical tankers, storage tanks, pressure vessels, heat exchangers, desalination plant, pulp-and-paper digesters, offshore piping and, increasingly, structural applications such as bridges and rebar in marine environments.
Limits: a service window of about −50 to +300 °C (sigma-phase and 475 °C embrittlement outside it), ferromagnetism, and higher forming loads. EN 1.4462, JIS SUS329J3L and GB 022Cr23Ni5Mo3N are the same grade.
Full data sheet for 2205 → · Equivalent grades →