ASTM A240 409 (S40900) Stainless Steel Pipe
ASTM A240 409 (S40900) Stainless Steel Pipe: Chemical Composition, Mechanical & Physical Properties
Comprehensive data sheet for ASTM A240 409 (UNS S40900) ferritic stainless steel pipe, covering chemical composition, mechanical properties, thermal and electrical physical properties, international equivalents, and application guidance.
Hot rolling, cold rolling, forming, welding, bending, moderate machining (annealed)
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ASTM A240 409 Stainless Steel Pipe Introduction
ASTM A240 409 (UNS S40900) is a titanium-stabilized ferritic stainless steel. It offers good oxidation resistance up to approximately 815 °C, excellent formability, and resistance to corrosion and stress corrosion cracking. The addition of titanium stabilizes carbon and nitrogen, minimizing sensitization and intergranular corrosion. It is not hardenable by heat treatment. The material is typically supplied in the annealed condition. Its moderate strength and cost-effectiveness make it ideal for automotive exhaust systems, heat exchangers, and other high-temperature, non-severe corrosion applications.
ASTM A240 409 Stainless Steel Pipe Chemical Composition
Chemical composition as specified in ASTM A240/A240M for UNS S40900. The titanium content is stabilized as Ti = 6×(C+N) minimum and not exceeding 0.75%. All other elements are restricted to meet ferritic structure and corrosion resistance requirements.
| Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.08 | Maximum |
| Manganese (Mn) | ≤ 1.00 | Maximum |
| Phosphorus (P) | ≤ 0.045 | Maximum |
| Sulfur (S) | ≤ 0.030 | Maximum |
| Silicon (Si) | ≤ 1.00 | Maximum |
| Chromium (Cr) | 10.5 - 11.75 | Range |
| Nickel (Ni) | ≤ 0.50 | Maximum |
| Titanium (Ti) | 6×(C+N) min / ≤ 0.75 | Minimum determined by carbon+nirrogen content; not to exceed 0.75 |
| Nitrogen (N) | ≤ 0.10 | Maximum (typically not reported, but restricted for Ti stabilization) |
| Iron (Fe) | Balance | Remainder |
ASTM A240 409 Stainless Steel Pipe Thermal and Electrical Physical Properties
Representative physical properties for Type 409 stainless steel in the annealed condition. Values may vary slightly depending on product form and temperature. The thermal conductivity and expansion are critical for thermal cycling applications like exhaust systems.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.80 | g/cm³ | At 20 °C |
| Modulus of Elasticity (E) | 200 | GPa | At 20 °C |
| Shear Modulus (G) | 77 | GPa | Approximate at 20 °C |
| Poisson's Ratio (ν) | 0.28 | - | At 20 °C |
| Thermal Expansion Coefficient (α) | 10.8 | 10⁻⁶/K | 20 – 100 °C |
| Thermal Expansion Coefficient (α) | 11.4 | 10⁻⁶/K | 20 – 500 °C |
| Thermal Conductivity (λ) | 25.0 | W/m·K | At 100 °C |
| Specific Heat Capacity (c) | 460 | J/kg·K | At 0 – 100 °C |
| Electrical Resistivity (ρₑ) | 0.60 | μΩ·m | At 20 °C |
ASTM A240 409 Stainless Steel Pipe Mechanical Properties
Minimum mechanical properties at room temperature for annealed condition as per ASTM A240. These values apply to sheet, strip, and plate. For pipe products, supplementary specifications (e.g., ASTM A312) may dictate additional requirements. Hardness values are informative.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Tensile Strength (Rm) | ≥ 380 | MPa | Transverse, annealed |
| Yield Strength (Rp0.2 / ReH) | ≥ 170 | MPa | Transverse, annealed |
| Elongation (A) | ≥ 20 | % | 50 mm gauge length (or 2 in.) |
| Hardness | ≤ 88 | HRB | Annealed |
| Hardness | ≤ 179 | HBW | Annealed |
| Bend Test | 180 °; bend factor = 1t | - | Thickness ≤ 25.4 mm (1.0 in.); no cracks |
ASTM A240 409 Stainless Steel Pipe Fully Equivalent Material Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240/A240M | 409 / S40900 | Original grade |
| Europe | EN 10088-2 | 1.4512 (X2CrTi12) | Direct equivalent; slight compositional tolerance differences |
| Japan | JIS G4304 / G4305 | SUH409L | Same type; used for heat-resistant applications |
| International | ISO 15510 | X6CrTi12 | ISO equivalent based on same nominal composition |
| China | GB/T 3280 | 06Cr11Ti (1.4512) | Chinese equivalent; often referred as 0Cr11Ti |
| Germany | DIN EN 10088-2 | 1.4512 | As per EN |
ASTM A240 409 Stainless Steel Pipe Application Introduction
ASTM A240 409 stainless steel pipe is a workhorse material for elevated-temperature service up to 815 °C, combining oxidation resistance and fabricability with low cost. It is almost exclusively used in the annealed condition and can be formed, welded, and moderately machined. Its titanium stabilization prevents sensitization during welding in thin sections, making it suitable for extensive exhaust piping and muffler components.
Product Applications: Automotive exhaust pipes, tailpipes, and tubing, Catalytic converter shells and internals, Mufflers and resonators, Heat exchanger tubes and plates, Furnace liners and supports, Agricultural sprayer booms and exhaust parts
Processed into products: Welded exhaust tubes and manifolds, Stamped muffler internals, Deep-drawn end caps, Bent pipe elbows, Thermal reactor parts, Hangers and brackets, Expansion joints
Application industries: Automotive – exhaust and emission control, Power generation – heat exchangers and ducts, Agricultural equipment – hot gas piping, Furnace manufacturing – combustion chambers, Architecture – indoor decorative panels
ASTM A240 409 Stainless Steel Pipe Similar or Near-Similar Substitute Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A240 | 409L (S40920) | Lower interstitial variant for enhanced toughness and weldability |
| USA | ASTM A240 | 439 (S43035) | Contains chromium ~17-19%; improved corrosion resistance but higher cost |
| USA | ASTM A240 | 410 (S41000) | Martensitic, hardenable; higher strength but less oxidation resistance |
| Europe | EN 10088-2 | 1.4003 (X2CrNi12) | Ferritic with small nickel addition, better weldability and toughness than 409 |
| Japan | JIS G4305 | SUS410L | Low carbon 13% Cr ferritic, better corrosion resistance than 409 |
Notes:
Welding: Readily welded by common fusion methods (GTAW, GMAW, resistance). Heat Treatment: Anneal at 815–870 °C, air cool or water quench; not hardenable by heat treatment. Corrosion Resistance: Good resistance to atmospheric corrosion and mild chemical environments; not suitable for severe acids or chlorides. Forming: Excellent cold formability. Availability: Typically supplied in sheet, strip, and welded pipe form per ASTM A240 and A268/A312.
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