1. Introduce
– Duplex stainless steel containing approximately 22% Cr, 5%Ni, 3%Mo
– Higher Cr, Mo, and N content provides superior corrosion resistance to 316 and 316L in most environments
– Nitrogen enhanced duplex stainless steel developed to address common corrosion problems encountered with 300 series stainless steels
– High pitting resistance index material with a PREN of 34 to 38
– Used in temperature range below 315°C and becomes brittle with prolonged high temperature exposure
– UNS S32205
* Duplex Stainless Steel
[Characteristics]
- 50:50 austenitic and ferritic organization
- Good corrosion resistance and strength, resistance to chloride erosion and crevice corrosion
→ Influence of Cr, Mo, W, N - Better chloride stress corrosion cracking resistance, strength, toughness, and plasticity than 300 series austenitic stainless steels
[Type]
| UNS NO. | Grade | Chemical Composition | Characteristics |
|---|---|---|---|
| S32304(2304) | Lean Duplex | 21Cr-3Ni-Mo-Cu-N | Low alloy type, Mo-free, PREN value 24 to 25, can be used in place of AISI 304 or 316 for stress corrosion resistance |
| S32205(2205) | Duplex | 22Cr-5Ni-3Mo-N | Heavy alloy type, PREN value 32 to 33 |
| S32550(255) | Duplex | 24Cr-5Ni-3Mo-N | High alloy type, alloy containing approx. 25%Cr, Mo, N, Cu, W, PREN value 38~39, better corrosion resistance than approx. 22%Cr duplex stainless steel |
| S32750(2507) | Super Duplex | 25Cr-7Ni-4Mo-N | Super duplex stainless steel, PREN value of 40 or higher, contains high amounts of Mo and N |
* Physicochemical Features
- Corrosion resistance (Chlorine corrosion environment)
→ SUS 316L ≒ 2304<2205<2507 - Mechanical strength (1.5~2 times better than austenitic series)
→ 2304<2205<2507
* PREN (Pitting Resistance Equivalent Number : Formula resistance index)
: Numerical value of resistance to pitting in chloride environment of stainless steel
: Pitting resistance is determined by the chemical elemental composition of stainless steel
→ Cr, Mo, N
* UNS
- Abbreviation for the Unified Numbering System for Metals and Alloys
- Unified unique numbering system for metals and alloys
- A representative number compatible with metals and alloys defined in several material-related codes, including ASTM, AISI, ASME, AWS, etc.
* S : Heat and corrosion resistant (stainless) steel
2. Property
– Excellent corrosion resistance, strength, localized corrosion and stress corrosion cracking resistance
| Element | Impact |
|---|---|
| Cr, Ni, Mo, N | Provides corrosion resistance, oxidation resistance, erosion and crevice corrosion resistance |
[2205 Duplex Chemical Composition (%)]
| C | Mn | P | S | Si |
|---|---|---|---|---|
| Max. 0.030 | Max. 2.00 | Max. 0.030 | Max. 0.020 | Max. 1.00 |
| Cr | Ni | Mo | N | |
|---|---|---|---|---|
| 22.0~23.0 | 4.5~6.5 | 3.0~3.5 | 0.14~0.20 |
[2205 Duplex Mechanical Properties]
| Tensile Strength (Mpa) | Yield Strength (Mpa) | Elongation (%) |
|---|---|---|
| Min. 655 | Min. 450 | Min. 25 |
[2205 Duplex Physical Properties]
| Density (g/㎤) | Melting Range (℃) | Specific Heat (0-100℃), J/kg*℃ |
|---|---|---|
| 7.8 | 1385~1443 | 450 |
3. Standard & Specification
– Specification : UNS S32205
| Product Form | ASTM | ASME |
|---|---|---|
| Bar, Rod | A276 | SA182, SA276, SA479 |
| Sheet, Plate, Strip | A240 | SA240 |
| Tube, Pipe | A790, A928, A270, A789 | SA240, SA790, SA789 |
| Fittings | A815 | SA815 |
4. Available Form
– Bar, Rod
– Sheet, Plate
– Tube, Pipe
– Fittings
– Wire
5. Application & Product
– Marine, Chemical, Oil & Gas
| Application | Product |
|---|---|
| Marine | Deepwater subsea structures, pipelines, seawater desalination plants |
| Chemical | Pressure vessels, high-pressure storage tanks, high-pressure pipelines |
| Oil & Gas | Oilfield piping |
(1) High-pressure storage tanks / (2) Oilfield piping / (3) Seawater desalination plants
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