022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil
022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel: High Strength, Excellent Corrosion Resistance for Harsh Environments
Explore 022Cr25Ni7Mo4WCuN austenitic-ferritic duplex stainless steel per GB/T 4237. Chemical composition, mechanical & thermal properties, international equivalents (UNS S32707, EN 1.4501), and application guide for plates and coils.
Hot rolling, cold rolling, welding, machining, forming
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022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil Introduction
022Cr25Ni7Mo4WCuN is a super duplex stainless steel with a mixed austenitic-ferritic microstructure, standardized under GB/T 4237 for hot-rolled plates and coils. It is alloyed with high chromium (24-26%), nickel (6-8%), molybdenum (3-4%), tungsten (0.5-1.0%), and copper (0.5-1.0%), along with controlled nitrogen (0.20-0.30%). This composition provides exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking in chloride-containing environments. The balanced dual-phase structure delivers high mechanical strength (yield strength ≥550 MPa) combined with good ductility and weldability. Compared to standard duplex grades, its higher alloy content ensures superior performance in aggressive media such as seawater, chemical processing, and oil & gas extraction. Typical applications include heat exchangers, desalination plants, and offshore equipment, where both strength and corrosion resistance are critical.
022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil Chemical Composition
The chemical requirements for 022Cr25Ni7Mo4WCuN as specified in GB/T 4237. The alloy relies on a high Cr, Mo, W, and N content to achieve excellent pitting resistance equivalent (PREN ≥ 40).
- Carbon is kept low to minimize carbide precipitation during welding.
- Tungsten and copper enhance corrosion resistance in acidic and chloride environments.
- Nitrogen improves strength and pitting resistance while stabilizing the austenite phase.
| Element | Standard Value (wt%) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.03 | Low carbon for corrosion resistance |
| Silicon (Si) | ≤1.00 | |
| Manganese (Mn) | ≤1.20 | |
| Phosphorus (P) | ≤0.035 | |
| Sulfur (S) | ≤0.020 | |
| Chromium (Cr) | 24.00-26.00 | Key for pitting resistance |
| Nickel (Ni) | 6.00-8.00 | Balances phase ratio |
| Molybdenum (Mo) | 3.00-4.00 | Improves crevice corrosion resistance |
| Tungsten (W) | 0.50-1.00 | Synergistic corrosion enhancement |
| Copper (Cu) | 0.50-1.00 | Resistance to reducing acids |
| Nitrogen (N) | 0.20-0.30 | Austenite stabilizer, strength booster |
022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil Thermal and Electrical Physical Properties
Typical physical properties for 022Cr25Ni7Mo4WCuN super duplex stainless steel at room temperature and elevated temperatures. These values are derived from published data for similar super duplex alloys and may vary slightly with processing.
- Density is slightly lower than pure austenitic grades due to the ferrite fraction.
- Thermal expansion is lower, reducing thermal stress in service.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.8 | g/cm³ | 20°C |
| Elastic Modulus (E) | 200 | GPa | 20°C |
| Shear Modulus (G) | 77 | GPa | 20°C, calculated from E and ν |
| Poisson's Ratio (ν) | 0.30 | - | 20°C |
| Thermal Expansion Coefficient (α) | 13.0 (20-100°C); 13.5 (20-200°C); 14.0 (20-300°C) | 10⁻⁶/K | Temperature range as indicated |
| Thermal Conductivity (λ) | 14 | W/(m·K) | 20°C |
| Specific Heat Capacity | 500 | J/(kg·K) | 20°C |
| Electrical Resistivity (ρ_e) | 0.85 | μΩ·m | 20°C |
022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil Mechanical Properties
Mechanical properties as per GB/T 4237 for hot-rolled plates. Testing is performed at room temperature after solution annealing. The high yield strength permits thinner sections in structural designs.
- Hardness values are approximate maximums; actual values may be lower.
- Elongation is measured using a gauge length of A50 mm for plate thickness ≥3 mm.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (Rp0.2) | ≥ 550 | MPa | Room temperature, transverse |
| Tensile Strength (Rm) | ≥ 750 | MPa | Room temperature, transverse |
| Elongation (A) | ≥ 25 | % | Gauge length A50, thickness ≥3 mm |
| Brinell Hardness (HBW) | ≤ 310 | - | Converted from Rockwell |
| Impact Energy (KV2) | ≥ 100 (typical) | J | -20°C, Charpy V-notch (for reference, not mandatory) |
022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil Completely Equivalent Material Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240/A240M | UNS S32707 | Super duplex, identical chemical range |
| Europe | EN 10088-2 | 1.4501 (X2CrNiMoCuWN25-7-4) | Fully equivalent composition and properties |
| International | ISO 15510 | X2CrNiMoCuWN25-7-4 | Matches GB grade |
| Japan | JIS G 4304 | SUS 32707 (tentative) | Adopted from UNS, similar specifications |
| China | GB/T 4237 | 022Cr25Ni7Mo4WCuN | Original specification |
022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil Application Introduction
022Cr25Ni7Mo4WCuN is selected for demanding applications requiring the highest corrosion resistance and mechanical strength in chloride-rich, acidic, or high-pressure environments. Key industry sectors include:
Product Applications: Plate heat exchangers, Shell and tube heat exchangers, Pressure vessels and reactors, Storage tanks for aggressive chemicals, Seawater piping systems, Centrifugal fans and pumps
Processed into products: Tube sheets for heat exchangers, Impellers and pump shafts, Valve bodies and internals, Flanges and fittings, Structural profiles for offshore platforms, Expansion joints, Welded pipe spools, Fasteners in critical bolting
Application industries: Chemical and petrochemical processing, Oil and gas (offshore platforms, subsea equipment), Marine engineering (desalination, shipbuilding), Pulp and paper (bleaching equipment), Flue gas desulfurization (FGD) scrubbers, Renewable energy (geothermal, biofuel)
022Cr25Ni7Mo4WCuN Super Duplex Stainless Steel Plate/Coil Similar or Alternative Materials with Close Properties
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240 | UNS S32750 (2507) | Super duplex without W and Cu; slightly lower PREN; good alternative for less aggressive chloride environments. |
| USA | ASTM A240 | UNS S32760 | Contains W and Cu but different Cr/Ni balance (Zeron 100 type); similar corrosion resistance; widely used in marine. |
| Europe | EN 10088-2 | 1.4410 (X2CrNiMoN25-7-4) | Super duplex, no W/Cu; often used where high mechanical strength is required; PREN slightly lower. |
| Europe | EN 10088-2 | 1.4507 (X2CrNiMoCuN25-6-3) | Leaner version with lower Mo; economical for less demanding conditions. |
| China | GB/T 4237 | 022Cr25Ni6Mo3Cu2N | Chinese super duplex with Cu but no W; lower pitting resistance. |
Notes:
For welded fabrications, post-weld solution annealing is recommended to restore full corrosion resistance and phase balance. Welding consumables with matching or over-alloyed composition (e.g., super duplex filler with higher Ni) are advised. The grade can be used in the annealed and quenched condition; aging treatments (475°C embrittlement) must be avoided. Maximum service temperature is typically limited to 300°C due to possible precipitation of intermetallic phases. When specifying, ensure compliance with GB/T 4237 or referenced international standards for guaranteed properties.
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