Duplex 2205 Tube Sheet
A 50/50 austenite-ferrite microstructure gives 2205 roughly double the yield strength of standard 316L stainless plus meaningfully better resistance to chloride pitting and stress-corrosion cracking — the default upgrade path once seawater or brine service pushes stainless past its limit.
Chemical Composition
| Element | Min % | Max % |
|---|---|---|
| Chromium (Cr) | 22.0 | 23.0 |
| Nickel (Ni) | 4.5 | 6.5 |
| Molybdenum (Mo) | 3.0 | 3.5 |
| Nitrogen (N) | 0.14 | 0.20 |
| Carbon (C) | — | 0.030 |
Pitting Resistance Equivalent Number (PREN)
Mechanical Properties
| Property | Typical Value |
|---|---|
| Tensile Strength | 620 MPa min |
| Yield Strength (0.2% offset) | 450 MPa min |
| Elongation | 25% min |
| Brinell Hardness | 293 HB max |
Equivalent Grades
| Standard | Designation |
|---|---|
| ASTM / UNS | S32205 |
| EN / DIN | 1.4462 |
| JIS | SUS329J3L |
The 2205 designation cross-reference explains why UNS S31803 and S32205 are associated with the same duplex family but should not be treated as identical callouts.
Available Product Forms
Duplex 2205 is most commonly ordered as Floating Tube Sheets for high-ΔT seawater cooling service, and as Forged Tube Sheets where large diameter and directional strength are both required.
Applicable Standards
Governed by ASTM A240/A182 for the material and TEMA / ASME Section VIII for the mechanical design.
Applications
2205 is the standard chloride-service upgrade from stainless — desalination, offshore oil & gas, and marine cooling water systems where 316L's PREN is no longer adequate but full super duplex or titanium isn't yet justified by cost.
Advantages & Limitations
Advantages
- Roughly double the yield strength of 316L — thinner sections possible
- Strong resistance to chloride stress-corrosion cracking
- Good cost-to-performance step up from austenitic stainless
Limitations
- Work-hardens faster, requiring different machining parameters
- Practical service temperature limit around 300°C
- Higher cost than standard stainless family
FAQ
When chloride concentration, temperature, or both push the required PREN above roughly 40 — super duplex 2507 offers a PREN around 42, at a further cost premium. 2205 covers the large majority of seawater and brackish-water applications adequately.
Yes — duplex welding requires controlled heat input to maintain the correct austenite-ferrite balance in the weld and heat-affected zone. This is standard practice for qualified duplex welders but isn't interchangeable with standard austenitic stainless welding procedures.
Yes, mildly — the ferrite phase (roughly half the microstructure) is magnetic, unlike fully austenitic stainless grades. This is a normal characteristic of duplex steel and doesn't indicate a material defect.