2205 Duplex Stainless Steel
2205 is a duplex stainless steel designed with a balanced structure of austenite and ferrite. It is widely selected when you need higher strength than 304/316 and better resistance to chloride-related corrosion.
Typical projects include offshore and marine systems, chemical process equipment, pressure vessels, and piping where stress corrosion cracking is a real risk.
Structure
Duplex (two-phase)
Balanced austenite + ferrite for strength and corrosion stability.
Strength level
High yield strength
Often close to double the yield strength of common 300-series grades.
Chloride resistance
Very strong
Good pitting and crevice corrosion resistance in chloride service.
Magnetic response
Slightly magnetic
Normal for duplex stainless due to the ferritic phase.
2205 is chosen for demanding environments where both corrosion resistance and load capacity matter. It is a practical option when nickel alloys are not required, but 304/316 do not offer enough margin.
- Oil and gas: offshore platforms, subsea pipelines, umbilicals, separators, pressure vessels
- Marine and desalination: seawater cooling systems, brine heaters, evaporators, condensers
- Chemical processing: tanks, heat exchangers, piping, scrubbers, mixers exposed to chlorides
- Pulp and paper: digesters, bleaching equipment, washers, chemical handling systems
- Structures: bridges and supports in coastal or polluted urban environments
- Food and beverage: salt-rich process lines, fermentation and storage equipment
Duplex grades may be listed under different national systems. Equivalents are for reference. Final acceptance should follow the project specification, inspection scope, and Mill Test Certificate.
| System | Designation | Note |
|---|---|---|
| ASTM / AISI | 2205 | Common market name |
| UNS | S31803 / S32205 | Both appear in RFQs; confirm exact requirement |
| EN | 1.4462 | European grade number |
| DIN | X2CrNiMoN22-5-3 | European naming format |
| JIS | SUS329J3L | Common in Asia documents |
| GOST | 08Х22Н6М2Т / 03Х22Н5АМ2 | Often seen in regional specifications |
| GB | 022Cr22Ni5Mo3N | China standard naming format |
- Higher strength: supports thinner wall design or higher pressure rating in many systems.
- Better chloride performance: strong pitting and crevice resistance compared with 304/316 in many chloride services.
- Stress corrosion cracking resistance: preferred for warm chloride environments where 300-series grades can crack.
- Good fatigue behavior: useful for cyclic service such as offshore equipment.
- Cost balance: often chosen as a middle route between 316L and nickel alloys for tough environments.
Limits vary slightly by standard and supply route. Use the Mill Test Certificate as the final verification for your delivered heat.
| Grade | Standard | C | Cr | Ni | Mo | Mn | Si | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|---|
| 2205 | ASTM A240 | ≤ 0.03 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | ≤ 2.0 | ≤ 1.0 | ≤ 0.03 | ≤ 0.02 | Balance |
| 1.4462 | EN 10088-2 | ≤ 0.03 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | ≤ 2.0 | ≤ 1.0 | ≤ 0.035 | ≤ 0.02 | Balance |
| SUS329J3L | JIS G 4304 / JIS G 4305 | ≤ 0.03 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | ≤ 2.0 | ≤ 1.0 | ≤ 0.03 | ≤ 0.02 | Balance |
Values depend on thickness and product form. Use the governing specification for acceptance and design.
| Property | Typical requirement | Notes |
|---|---|---|
| Tensile strength | ≥ 620 MPa | Reference requirement for common specifications |
| Yield strength | ≥ 450 MPa | High yield is a key reason to choose 2205 |
| Elongation | ≥ 25% | Supports forming when tooling is correct |
| Hardness | ≤ 290 HBW | Confirm by thickness and condition |
2205 is known for strong resistance to pitting and crevice corrosion in many chloride environments, plus improved resistance to stress corrosion cracking compared with 300-series stainless steels.
Duplex stainless steel is not recommended for long-term exposure at elevated temperatures where phase changes can reduce toughness. For long-duration service above about 250°C, discuss alternative grades designed for high-temperature stability.
2205 can be supplied in common stainless product forms. Availability depends on finish, tolerance, straightness, and inspection scope. Share your sizes and end use to match the best supply route.
| Form | Typical size range | Notes |
|---|---|---|
| Sheet (cold rolled) | 0.3–6.0 mm, width 1000–2000 mm | Common for fabrication and cut-to-length |
| Plate (hot rolled) | 3–100 mm, width 1000–2000 mm | Used for pressure vessels and heavy fabrication |
| Cold-rolled coil | 0.3–6.0 mm, width 1000–2000 mm | Slitting and cut-to-length available |
| Hot-rolled coil | 3–14 mm, width 1000–2000 mm | For thicker coil supply routes |
| Strip | 0.3–10 mm, width 7–600 mm | Often used for formed parts |
| Seamless pipe | OD ≤ 610 mm, WT 1–100 mm | Confirm NDT and impact testing if needed |
| Welded pipe | OD 6–3000 mm, WT 1–100 mm | Define welding method and surface requirement |
| Round bar | Diameter 1–200 mm, length 100–12000 mm | Machining and fabricated parts |
| Flat bar | Width 20–800 mm, thickness 3–60 mm | Frames and structural supports |
| Angle bar | Side 20–250 mm, thickness 3–35 mm | Project supply by section size |
| Channel | Height 50–400 mm, thickness 4–20 mm | Project supply by section size |
| H beam | Height 100–1000 mm, thickness 6–40 mm | Project-based supply |
- Forming: requires higher forming force than 304/316 and has more springback. Use a suitable bend radius.
- Complex shaping: for difficult parts, controlled heating can reduce cracking risk during forming.
- Welding: good weldability with correct procedures. Keep heat input and interpass temperature controlled.
- Filler selection: ER2209 is commonly used for balanced weld properties in many projects.
- Post-weld care: cleaning, pickling, and passivation help restore corrosion performance.
- Machining: use rigid tooling and effective cooling; stable feeds help reduce surface hardening.
2205 can be supplied in standard stainless finishes such as 2B, No.1, No.4, HL, BA, and mirror finishes. For chloride service, surface cleanliness matters as much as grade selection.
After fabrication, surface restoration is recommended to remove heat tint and embedded contamination. This helps maintain corrosion resistance in real operating conditions.
These grades are often compared in sourcing. 304 and 316L are widely used general-purpose stainless steels. 2205 is selected when you need higher strength and better chloride-related reliability.
| Property | 304 | 316L | 2205 Duplex |
|---|---|---|---|
| Strength | Moderate | Moderate | Very high |
| Corrosion resistance | Good | Excellent | Excellent (especially chlorides) |
| Stress corrosion cracking | Poor | Moderate | Excellent |
| Cost position | $ | $$ | $$–$$$ |
| Magnetic | No | No | Slightly |
Use these internal tools to confirm equivalents, estimate weight, and prepare a clear RFQ before purchasing.
Why choose 2205 duplex stainless steel over 304 or 316L?
2205 offers higher strength and stronger resistance to chloride-related corrosion, including stress corrosion cracking. It is often selected for offshore, chemical, and pressure equipment where 304/316L may not provide enough margin.
Is 2205 duplex stainless steel magnetic?
Yes. 2205 is usually slightly magnetic due to its ferritic phase. This is normal and does not reduce its corrosion performance.
Can 2205 be welded easily?
Yes, when welding procedures control heat input and maintain a balanced structure. Filler metals such as ER2209 are commonly used, and post-weld cleaning helps restore the surface.
How does 2205 compare with super duplex 2507?
2205 is a balanced cost-performance option for many chloride-rich environments. Super duplex 2507 is used when exposure is extreme, such as high-chloride seawater or very aggressive chemical service, and the design needs more corrosion margin.
Is 2205 suitable for high-temperature service?
2205 is not recommended for long periods above about 250°C due to reduced toughness over time. For high-temperature stability, select grades designed for that duty and confirm the design temperature range.
Is 2205 food safe?
2205 is used in food equipment, especially where chloride exposure is high, such as seafood processing or brine handling. Final compliance depends on your local regulation and the required surface condition.