ASTM A240 2304 (S32304) Duplex Stainless Steel Pipe
ASTM A240 2304 (UNS S32304) Duplex Stainless Steel Pipe: Data, Properties & Equivalents
Comprehensive material data for ASTM A240 2304 (UNS S32304) duplex stainless steel pipe, covering chemical composition, mechanical and physical properties, international equivalents, and application guidance.
Hot rolling, cold rolling, forming, welding, machining
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ASTM A240 2304 Duplex Stainless Steel Pipe Introduction
2304 stainless steel (UNS S32304) is a low-alloy duplex stainless steel containing approximately 22% chromium, 4.8% nickel, and 0.3% molybdenum. Specified primarily in ASTM A240 for flat-rolled products, it is also widely used in tubular forms under ASTM A790. This grade offers a balanced combination of high strength and excellent corrosion resistance, particularly to stress corrosion cracking, pitting, and crevice corrosion. Compared to 304L and 316L austenitic grades, 2304 provides nearly twice the yield strength while maintaining good toughness and weldability. Its lean composition makes it cost-effective for many applications in chemical processing, heat exchangers, and marine environments.
ASTM A240 2304 Duplex Stainless Steel Pipe Chemical Composition per ASTM A240 for UNS S32304
The chemical composition of 2304 duplex stainless steel is tightly controlled to achieve the desired duplex microstructure. Key alloying elements include chromium (Cr) for corrosion resistance, nickel (Ni) for austenite stabilization, molybdenum (Mo) for pitting resistance, and nitrogen (N) for enhanced strength and corrosion resistance. Copper addition improves general corrosion resistance in reducing environments.
| Element | Specification (min–max or max) | Notes |
|---|---|---|
| Carbon (C) | ≤ 0.030 | |
| Manganese (Mn) | ≤ 2.50 | |
| Phosphorus (P) | ≤ 0.040 | |
| Sulfur (S) | ≤ 0.030 | |
| Silicon (Si) | ≤ 1.00 | |
| Chromium (Cr) | 21.5 – 24.5 | |
| Nickel (Ni) | 3.0 – 5.5 | |
| Molybdenum (Mo) | 0.05 – 0.60 | |
| Nitrogen (N) | 0.05 – 0.20 | |
| Copper (Cu) | 0.05 – 0.60 |
ASTM A240 2304 Duplex Stainless Steel Pipe Thermal and Electrical Physical Properties
Physical property data are based on the European equivalent grade 1.4362 (X2CrNiN23-4) per EN 10088-2 and published literature. Values are typical for material in solution-annealed condition and may vary with temperature and processing.
| Property | Value | Unit | Test Condition / Reference |
|---|---|---|---|
| Density (ρ) | 7.8 | g/cm³ | Room temperature |
| Modulus of Elasticity (E) | 200 | GPa | Room temperature, tension |
| Shear Modulus (G) | 77 | GPa | Room temperature, calculated |
| Poisson Ratio (ν) | 0.30 | – | Room temperature |
| Thermal Expansion Coeff. (α) | 13.0 | 10⁻⁶/K | 20 – 100 °C |
| Thermal Expansion Coeff. (α) | 13.5 | 10⁻⁶/K | 20 – 200 °C |
| Thermal Expansion Coeff. (α) | 14.0 | 10⁻⁶/K | 20 – 300 °C |
| Thermal Conductivity (λ) | 15 | W/m·K | 20 °C |
| Thermal Conductivity (λ) | 16 | W/m·K | 100 °C |
| Thermal Conductivity (λ) | 18 | W/m·K | 200 °C |
| Specific Heat Capacity | 480 | J/kg·K | 20 °C |
| Electrical Resistivity (ρ_e) | 0.80 | µΩ·m | Room temperature |
ASTM A240 2304 Duplex Stainless Steel Pipe Mechanical Properties
The mechanical properties apply to solution-annealed material in thicknesses up to 0.25 inch (6.35 mm). Values represent minimum requirements unless noted otherwise. The duplex structure provides significantly higher yield strength than common austenitic grades, allowing for thinner wall designs in pressure applications.
| Property | Value | Unit | Condition |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 600 (87) | MPa (ksi) | Room temperature, transverse or longitudinal |
| Yield Strength (ReH, 0.2% offset) | ≥ 400 (58) | MPa (ksi) | Room temperature |
| Elongation (A, 2 in. or 50 mm) | ≥ 25 | % | Gauge length 2 in. (50 mm) |
| Hardness, Rockwell | ≤ 100 HRB | HRB | As annealed |
| Hardness, Brinell | ≤ 293 HBW | HBW | As annealed |
| Bend Test (Bend angle 180°) | Bend diameter = 2 × thickness | – | For thickness ≤ 0.375 in. (9.5 mm) |
ASTM A240 2304 Duplex Stainless Steel Pipe Fully Equivalent International Standards and Replacement Grades
| Country/Region | Standard | Grade Designation | Remarks |
|---|---|---|---|
| Europe | EN 10088-2 / EN 10088-3 | 1.4362 (X2CrNiN23-4) | Chemically identical, equivalent mechanical properties |
| China | GB/T 20878, GB/T 3280 | 022Cr23Ni4MoCuN / S32304 | Matches UNS S32304 composition |
| Japan | JIS G4304 / G4305 | SUS32304 | Equivalent to ASTM A240 2304 |
| International | ISO 15510 | X2CrNiN23-4 | Harmonized grade |
| USA (pipe standard) | ASTM A790 / A790M | UNS S32304 | Seamless and welded duplex stainless steel pipe |
ASTM A240 2304 Duplex Stainless Steel Pipe Application Introduction
2304 duplex stainless steel is widely adopted where a balance of high mechanical strength, good corrosion resistance, and cost efficiency is required. It is particularly effective in reducing the risk of stress corrosion cracking (SCC) in chloride-containing environments, which limits the use of standard austenitic grades. Its high yield strength enables lighter design, saving weight and material costs. Typical service temperature range is from -50°C to 300°C.
Product Applications: Pressure vessels and storage tanks, Heat exchanger tubes and shell, Process piping systems, Oil & gas flowlines and manifolds, Seawater handling equipment, Pulp mill digesters and liquor tanks, Desalination plant components
Processed into products: Tube and pipe fittings (flanges, elbows, tees), Valve bodies and trim, Pump shafts and impellers, Welded structures and fabricated frames, Tanks and vessel shells, Heat exchanger plates and tubesheets, Fasteners and bolting
Application industries: Chemical and petrochemical processing, Oil and gas (topsides, piping), Marine and offshore engineering, Pulp and paper industry (digesters, bleaching equipment), Water treatment and desalination, Heat exchangers and boilers, Food and beverage processing equipment, Structural and architectural applications
ASTM A240 2304 Duplex Stainless Steel Pipe Similar or Alternative Duplex and Austenitic Stainless Steels
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240 | 2205 (S32205/S31803) | Higher Mo (3.0–3.5%) and Ni (4.5–6.5%), superior pitting resistance, stronger but more expensive |
| Europe | EN 10088-2 | 1.4462 (X2CrNiMoN22-5-3) | Standard 22Cr duplex, enhanced corrosion resistance over 2304 |
| USA | ASTM A240 | 316L (S31603) | Austenitic, lower strength, similar corrosion resistance in many media, higher Ni content |
| USA | ASTM A240 | 304L (S30403) | Austenitic, lower strength, less resistant to chloride SCC, widely used for general corrosion |
Notes:
For applications requiring ASME Boiler and Pressure Vessel Code certification, ensure the material is supplied with appropriate markings per ASTM A240 and, if for piping, per ASTM A790. Welding consumables should match or slightly over-alloy (e.g., ER2209 or similar) to compensate for alloy loss. Post-weld heat treatment is not typically required for thicknesses up to 20 mm, but may be considered for heavy sections or stress corrosion critical environments. The grade exhibits good formability, but higher springback than austenitic grades should be considered during cold working.
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