Selection summary
Overview
2205 duplex stainless combines ferritic and austenitic phases to deliver substantially higher strength than common 300-series grades and improved resistance to chloride stress-corrosion cracking. Welding and heat treatment must preserve phase balance, making qualified fabrication essential.
This page separates standard-oriented limits from typical reference data. Purchase acceptance comes from the ordered specification and certified material test report.
Names and systems
Identity & standards
Similar designations across ASTM, EN, JIS, and other systems are not automatically interchangeable. Product form and ordered standard control chemistry, properties, dimensions, condition, and testing.
Reference chemistry
Composition
| Element | Reference range | Why it matters |
|---|---|---|
| Chromium | ≈ 22% | Passive-film and pitting resistance |
| Nickel | ≈ 5% | Austenite balance |
| Molybdenum | ≈ 3% | Localized corrosion resistance |
| Nitrogen | Alloyed addition | Strength, pitting resistance, phase balance |
Concise grade-family reference only. Confirm every element limit against the current standard for the exact product ordered.
Condition matters
Reference properties
Annealed flat product; verify UNS and standard
Annealed flat product; verify UNS and standard
Typical room-temperature reference
Environment first
Corrosion behavior
Often provides better pitting, crevice, and chloride stress-corrosion performance than 316L.
Not universally immune to seawater attack; temperature, flow, deposits, and crevices remain important.
Temperature, concentration, deposits, crevices, stress, surface finish, cleaning, and fabrication quality can change service performance.
Service limits
Temperature & service
Avoid uncontrolled high-temperature exposure that can form harmful intermetallic phases; follow the construction code.
Delivery condition
Heat treatment & condition
2205 requires solution annealing in the product-appropriate range followed by rapid cooling to restore the intended ferrite-austenite balance and corrosion resistance.
It is not hardened by thermal treatment. Uncontrolled time at elevated temperature can precipitate harmful phases, so hot work, welding heat input, interpass temperature, and postweld treatment need qualified controls.
Process route
Fabrication
Requires higher forming forces than 300-series austenitic grades.
Heat input, interpass temperature, filler, and cooling must maintain suitable ferrite-austenite balance.
Magnetic response: Ferromagnetic because of its duplex microstructure.
Decision boundaries
Comparisons & substitution
2205 offers higher strength and usually better chloride stress-corrosion and pitting resistance than 316L, but fabrication and phase-balance controls are more demanding.
Lean duplex grades may suit less aggressive exposure, while super duplex 2507 is considered for more severe chloride conditions; neither substitution is automatic.
Where it is used
Applications
Ordering scope
Product forms & standards
Plate, sheet, and strip ordered as UNS S32205 or the explicitly permitted designation under the flat-product standard.
Seamless and welded pipe or tube with product-specific heat treatment, corrosion testing, and weld controls.
Bar, forgings, fittings, and flanges under their own standards; a flat-product certificate does not qualify another form.
Decision support
Selection guidance
Choose this grade when
- Higher strength and improved chloride stress-corrosion resistance can reduce section or risk.
- A qualified duplex fabrication and inspection route is available.
Review another grade when
- Complex cold forming dominates the design.
- Service temperature lies outside the grade's qualified duplex range.
Before ordering
Procurement checklist
Name the governing product standard, edition, dimensions, tolerances, edge, finish, and delivery condition.
Require the exact UNS designation and a material test report; a familiar trade name alone is not an acceptance criterion.
Confirm corrosion environment, design temperature, fabrication route, inspection, certification, marking, and packaging before order release.
Traceable evidence