2205
1.4462 · EN 10088 / ASTM A276 · 1.4462
2205 is a stainless steel (Duplex family) to EN 10088 / ASTM A276 (1.4462). It has a specified 0.2 % proof stress of 460 MPa and a typical tensile strength of about 640 MPa, with a uniform elongation of 25 %. For nonlinear FEA, a bilinear model uses E = 200 GPa up to yield and a tangent modulus of 732 MPa above it. The mixed ferrite/austenite (duplex) structure combines high strength with strong resistance to chloride pitting and stress-corrosion cracking.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 25.0% · conservative analysis limit ½εu = 12.5%
Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.
Ratings — engineering judgement
Weldabilitygood
Weldable, but the ferrite/austenite balance must be preserved — control heat input, use an over-alloyed (nitrogen-bearing) filler such as 2209, and avoid slow cooling that grows ferrite or precipitates sigma phase.
Formabilitymoderate
Higher strength means higher forming forces and more spring-back than austenitics; hot-form in the 1000–1200 °C range and re-solution-anneal.
Machinabilitymoderate
Tougher on tooling than 304/316 owing to the higher strength and work-hardening — rigid setups, sharp carbide, generous coolant.
Corrosion resistanceexcellent
PREN ~35 — excellent pitting and crevice resistance and, crucially, far better chloride stress-corrosion-cracking resistance than austenitics. Suited to seawater and hot chloride process.
Hardenabilitynone
Not hardenable by heat treatment; strength comes from the duplex structure and nitrogen, not quenching.
Toughnessgood
Good down to about −40/−50 °C, but the ferrite phase gives a transition — not for deep cryogenic service, and avoid the 300–1000 °C embrittlement range in service.
Expert notes
2205 is the duplex people mean when they say “duplex”. It roughly doubles the proof strength of 304/316 while also out-performing them on chloride pitting and — the headline property — stress-corrosion cracking. For chloride-laden service you get more strength and more corrosion resistance at once, which is why it displaces austenitics in oil-and-gas, seawater and chemical plant.
Two things to respect. First, the microstructure is the material: welding and hot working must keep the ferrite/austenite balance near 50/50. Too much heat (or too slow cooling) grows ferrite and can precipitate brittle sigma phase, wrecking both toughness and corrosion resistance — use a nitrogen-bearing over-alloyed filler (2209) and control interpass temperature.
Second, it has a service-temperature ceiling around 250–300 °C: above that (and in the classic 475 °C embrittlement range) the ferrite embrittles over time. It is also not for deep cryogenic duty, where the ferrite transition bites — that’s austenitic territory.
Unlike the austenitics it is ferromagnetic, and it work-hardens hard, so allow for tooling and forming forces. Its PREN of ~35 puts it comfortably above 316 for pitting; step up to super-duplex (2507) only when you truly need it.
Mechanical properties
| Condition | Section | Yield (MPa) |
|---|---|---|
| 2205 · solution annealed + quenched | t ≤ 75 mm | 460 |
UTS 640–840 MPa · Impact ≥ 100 J @ 20 °C · Hardness ≤ 290 HB
Physical properties
| Density | 7800 | kg/m³ |
| Elastic modulus | 200 | GPa |
| Shear modulus | 77 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 13.0 | ×10⁻⁶/°C |
| Thermal conductivity | 16 | W/(m·K) |
| Specific heat | 500 | J/(kg·K) |
| Magnetic | Yes |
Chemical composition (wt %)
Available forms
Equivalent grades
| Standard | Grade | Note |
|---|---|---|
| EN 10088 | X2CrNiMoN22-5-3 / 1.4462 | |
| UNS | S32205 / S31803 | |
| ASTM | A182 F51 | |
| Trade | SAF 2205 | Original Sandvik designation. |
Historical designations
| Standard | Grade | Note |
|---|---|---|
| Trade | 3RE60 | An early (lean) duplex forerunner from the 1970s. |
| UNS | S31803 | Original 2205; S32205 tightened the N range for better weld performance. |
Common applications
- Oil, gas and chemical process equipment
- Seawater and desalination systems
- Chloride-bearing tanks, vessels and heat exchangers
- Pulp-and-paper and flue-gas plant
- Structural components needing strength plus corrosion resistance
- Pump, valve and shaft components
History
Duplex stainless steels combine ferrite and austenite to beat both on strength and chloride resistance. 2205 emerged in the 1970s–80s and became the standard-bearer of the family.
- 1930First duplex compositions trialled
- 1970Modern nitrogen-alloyed duplex grades developed (e.g. 3RE60)
- 19802205 (S31803) commercialised as the workhorse duplex
- 1996S32205 refines the composition for consistent weld properties