ASTM A268 TP409 Stainless Steel Tube UNS S40900 Seamless Steel Heat Exchanger Tube
ASTM A268 UNS S40900 / TP409 Ferretic Stainless Steel Seamless Tube Heat Exchanger Tube
ASTM A268 TP409 (UNS S40900) is a ferritic, titanium-stabilized stainless steel seamless heat exchanger tube. It offers moderate corrosion and high-temperature oxidation resistance, good weldability/formability, magnetic structure, and low nickel cost. Supplied annealed or pickled, it commonly serves condensers, coolers, exhaust, and EGR systems. Minimum tensile strength is 380 MPa per ASTM A268/A268M. Typical applications include shell-and-tube heat exchanger tubes.
Key Characteristics
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Good resistance to high-temperature oxidation and exhaust gas corrosion.
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Good weldability and formability.
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Moderate corrosion resistance — better than carbon steel, but generally lower than 304/316 stainless steel.
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Not recommended for severe chloride, marine, or strongly corrosive environments.
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Lower cost than austenitic grades because of its low nickel content.
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Titanium stabilization improves resistance to intergranular corrosion after welding.
| Grade | UNS | Family | Key composition | Corrosion | High-temp | Weldability | Typical use |
|---|---|---|---|---|---|---|---|
| TP405 | S40500 | Ferritic | ~12Cr + Al | Moderate | Good oxidation/sulfur | Good | Heat exchangers, condensers, refinery |
| TP409 | S40900 | Ferritic | ~11Cr + Ti | Moderate | Good to ~700°C | Good | Auto exhaust, EGR, heat exchangers |
| TP410 | S41000 | Martensitic | ~12Cr | Low–moderate | Limited | Poor | High strength, valves, pumps, cutlery |
| TP430 | S43000 | Ferritic | ~17Cr | Better | Good | Good | Food, nitric acid, appliances, general heat exchangers |
| TP444 | S44400 | Ferritic | ~18Cr + 2Mo + Ti/Nb | Best of these; pitting/chloride resistant | Good | Good | Hot water, solar, heat exchangers, 316L替代 |
| TP446 | S44600 | Ferritic | ~25Cr | Oxidation resistant | Excellent | Fair | High-temp furnace parts |
Equivalent Grade of ASTM A268 TP409 Stainless Steel Tube UNS S40900 Seamless Steel Heat Exchanger Tube
| STANDARD | WERKSTOFF NR. | UNS | JIS |
| TP409 | 1.4512 |
UNS S40900 |
SUS409 |
Chemical Composition % of ASTM A268 TP409 Stainless Steel Tube UNS S40900 Seamless Steel Heat Exchanger Tube
| C | Mn | P | S | Si | Ni | Ti | Cr |
| ≤0.08% | ≤1.00% | ≤0.045% | ≤0.030% | ≤1.00% | ≤0.5% | 6*C min, 0.75 max | 10.5%~11.7% |
*UNS S40900 often specifies Ti as 6 × (C + N) min, 0.75 max. Nitrogen may be limited to about 0.030 max in some product specifications.
Mechanical Properties of ASTM A268 TP409 Stainless Steel Tube UNS S40900 Seamless Steel Heat Exchanger Tube
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness |
| TP409 |
≥380 MPa |
≥170 MPa |
≥20% |
88 HRB max |
Heat Treatment
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Annealing temperature: 815–900 °C (1500–1650 °F), followed by air cooling.
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Supplied in annealed, pickled, bright-annealed, or polished condition depending on order.
Application
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Shell-and-tube heat exchangers
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Condensers and air coolers
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Feedwater heaters
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Automotive exhaust heat exchangers
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EGR coolers
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Catalytic converter components
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Furnace parts and high-temperature exhaust systems
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