18Cr-4Ni Duplex Stainless (var. 3)

18Cr-4Ni duplex stainless steel is a two-phase ferritic-austenitic alloy that combines the corrosion resistance of austenitic stainless steels with the strength and stress-corrosion cracking resistance of ferritic grades, positioned as a cost-effective alternative to higher-nickel duplex variants. This material is widely employed in chemical processing, desalination plants, offshore platforms, and pulp-and-paper manufacturing where resistance to chloride corrosion and pitting is critical, particularly in moderately aggressive environments where standard austenitic grades (like 304/316) would require thicker sections or more frequent maintenance. Engineers select this composition for applications demanding both corrosion performance and mechanical strength without the premium cost or nickel supply constraints of super-duplex grades, making it especially attractive for large structural components and pressure equipment in marine and industrial settings.