254SMO stainless round bar (ASTM A276; UNS S31254) is a super-austenitic alloy designed for seawater resistance, with a specialized chemistry: 19.5–20.5% chromium (Cr), 17.5–18.5% nickel (Ni), 6.0–6.5% molybdenum (Mo), 0.5–1.0% copper (Cu), and 0.18–0.22% nitrogen (N).
This high alloy content (especially Mo and N) gives it exceptional pitting resistance (PREN 42) in seawater, far exceeding 316L (PREN 32). Its mechanical properties include 650 MPa minimum tensile strength, 300 MPa yield strength, and 40% elongation, maintaining ductility in marine environments. 254SMO is used in desalination plants, offshore rigs, and seawater pipelines, with Made-in-China listings marketing it as "254SMO Seawater-Resistant Round Bar."