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Stainless Steel

2205 Duplex Stainless

2205 is a duplex stainless with a roughly 50/50 austenite-ferrite microstructure, delivering both high strength and excellent corrosion resistance. At 655 MPa tensile and 450 MPa yield it roughly doubles the yield of standard austenitics, while its corrosion rating of 5 reflects strong resistance to chlorides and stress-corrosion cracking, the failure mode that plagues 304 and 316.

How 2205 Duplex Stainless machines

Machinability is low at 1.8/5. The high strength and duplex structure make 2205 tougher to cut than austenitic stainless, with high cutting forces and rapid tool wear. Use rigid setups, sharp coated carbide, generous flood coolant, lower speeds with firm feeds, and avoid dwelling, which work-hardens the surface.

Manufacturing & processing

2205 is processed by CNC, sheet metal, and forging. It is used in the solution-annealed condition and is not precipitation hardened; control of the austenite-ferrite balance during welding and any heat exposure is critical to preserve corrosion resistance and toughness. Improper thermal cycles can precipitate brittle intermetallic phases.

Typical applications

Best for high-strength chloride-rich service. Common uses include offshore and marine equipment, seawater piping, oil and gas hardware, chemical process vessels, heat exchangers, and pollution-control systems where both mechanical loading and aggressive chloride corrosion must be handled together.

When to choose it

Choose 2205 when 316 lacks the strength or chloride/SCC resistance for marine and process environments. If corrosion is mild, a standard austenitic is cheaper and easier to machine. For severe acids beyond chlorides, consider a super-austenitic like 904L.

Suitable surface finishes

Common finishes for 2205 Duplex Stainless: passivation, electropolishing, bead blasting, brushed. Use the finish selector →

FAQ

Why is 2205 stronger than 304 or 316?
Its dual-phase austenite-ferrite microstructure roughly doubles yield strength to 450 MPa versus around 215 to 240 MPa for standard austenitics. This lets designers reduce wall thickness and weight while also improving resistance to chloride stress-corrosion cracking in service.
Is 2205 resistant to stress-corrosion cracking?
Yes, markedly more than 304 and 316. The ferrite phase in the duplex structure strongly resists chloride stress-corrosion cracking, the failure mode that plagues austenitics, which is why 2205 is favored for warm seawater, brine, and chloride-bearing process streams.
What makes 2205 harder to machine?
Its high strength and work-hardening duplex structure raise cutting forces and accelerate tool wear, earning a 1.8/5 rating. Success requires rigid machines, sharp coated carbide, generous flood coolant, lower speeds, and steady feeds without dwelling that would harden the surface.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.