ASTM A789 S31500 Duplex Stainless Steel Pipe
ASTM A789 S31500 Duplex Stainless Steel Pipe Data – Composition, Properties & Equivalents
Complete material data sheet for ASTM A789 S31500 duplex stainless steel pipe. Includes chemical composition, mechanical and physical properties, international equivalents, and typical applications.
Hot forming, cold working, machining, welding (with appropriate filler), heat treatment
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ASTM A789 S31500 Duplex Stainless Steel Pipe Introduction
UNS S31500 is a low-alloy duplex (ferritic-austenitic) stainless steel supplied as seamless and welded pipes under ASTM A789. It combines high strength with excellent resistance to stress corrosion cracking and moderate corrosion resistance. The microstructure contains approximately equal parts ferrite and austenite, giving it superior mechanical properties compared to standard austenitic grades. Typical delivery condition is solution annealed at 1020–1100°C followed by rapid cooling. This grade is particularly suited for pulp and paper industry equipment where high chloride environments demand stress corrosion cracking resistance.
ASTM A789 S31500 Duplex Stainless Steel Pipe Chemical Composition
Chemical composition as specified in ASTM A789 for UNS S31500 duplex stainless steel. The alloy is characterized by a low carbon content, controlled nitrogen addition, and a balanced ferrite-austenite phase composition achieved through chromium, nickel, molybdenum, and silicon.
| Element | Standard Value (wt%) | Notes |
|---|---|---|
| Carbon (C) | ≤ 0.03 | |
| Manganese (Mn) | 1.20 – 2.00 | |
| Phosphorus (P) | ≤ 0.030 | |
| Sulfur (S) | ≤ 0.030 | |
| Silicon (Si) | 1.40 – 2.00 | |
| Nickel (Ni) | 4.3 – 5.2 | |
| Chromium (Cr) | 18.0 – 19.0 | |
| Molybdenum (Mo) | 2.50 – 3.00 | |
| Nitrogen (N) | 0.05 – 0.10 | |
| Iron (Fe) | Balance |
ASTM A789 S31500 Duplex Stainless Steel Pipe Thermal and Electrical Physical Properties
Typical physical properties for UNS S31500 duplex stainless steel at room temperature and elevated temperatures. These values are indicative and may vary slightly with product form and heat treatment. They are not mandatory requirements of ASTM A789.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.8 | g/cm³ | At 20°C |
| Elastic Modulus (E) | 200 | GPa | At 20°C |
| Shear Modulus (G) | 78 | GPa | At 20°C |
| Poisson's Ratio (ν) | 0.3 | - | At 20°C |
| Thermal Expansion (α) | 13.0 | µm/m·°C | 20 – 100°C |
| Thermal Expansion (α) | 13.5 | µm/m·°C | 20 – 200°C |
| Thermal Expansion (α) | 14.0 | µm/m·°C | 20 – 300°C |
| Thermal Conductivity (λ) | 15 | W/(m·K) | At 20°C |
| Specific Heat Capacity | 500 | J/(kg·K) | At 20°C |
| Electrical Resistivity (ρ_e) | 0.80 | µΩ·m | At 20°C |
ASTM A789 S31500 Duplex Stainless Steel Pipe Mechanical Properties
Minimum mechanical properties at room temperature for S31500 pipes in solution-annealed condition, as required by ASTM A789. These values ensure adequate strength and ductility for demanding applications.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 440 | MPa | Room temperature, annealed, transverse/longitudinal per ASTM A370 |
| Tensile Strength (Rm) | ≥ 630 | MPa | Room temperature, annealed, transverse/longitudinal per ASTM A370 |
| Elongation (A) | ≥ 30 | % | In 50 mm (2 in.) gauge length, room temperature |
ASTM A789 S31500 Duplex Stainless Steel Pipe Exact Equivalents – Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 20878 | 022Cr19Ni5Mo3Si2N (S21953) | Identical chemical composition and mechanical properties. |
| International | ISO 15510 | X2CrNiMoSi18-5-3 | Fully equivalent grade under ISO standard. |
ASTM A789 S31500 Duplex Stainless Steel Pipe Application Introduction
UNS S31500 duplex stainless steel pipe is primarily used where high resistance to stress corrosion cracking (SCC) is required, especially in chloride-containing environments. Its mechanical strength allows thinner wall thicknesses compared to austenitic grades, reducing weight and cost. Typical service temperatures are between -50°C and 300°C.
Product Applications: Digesters and bleaching towers, Chemical evaporators, Heat exchangers and condensers, Piping systems for corrosive fluids, Storage tanks
Processed into products: Seamless and welded tubes, Pipe fittings (elbows, tees, reducers), Flanges and gaskets, Expansion joints, Tube sheets for heat exchangers
Application industries: Pulp and Paper, Chemical Processing, Oil and Gas, Desalination, Food Processing
ASTM A789 S31500 Duplex Stainless Steel Pipe Similar/Alternative Materials Recommendation
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10088-3 | X2CrNiMoN18-5-3 (1.4424) | Lower Si (≤1.0%) reduces strength slightly; suitable substitute in less aggressive chloride environments. |
| USA/Global | ASTM A789 | S32205 (UNS S32205, 2205) | Higher Cr, Mo, N content; provides superior corrosion resistance and higher strength. Use when enhanced pitting resistance is needed. |
Notes:
- Welding must follow established procedures for duplex grades; typically using over-alloyed fillers (e.g., ER2209) to maintain phase balance.
- Post-weld solution annealing may be required to restore corrosion resistance and mechanical properties.
- Intergranular corrosion testing per ASTM A262 Practice E is often specified for critical applications.
- Hardness values are not mandatory in ASTM A789 but are typically below 290 HBW in solution-annealed condition.
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