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ASTM A789 UNS S31803 1.4462 Seamless and Welded Duplex Stainless Steel Tube
ASTM A789 UNS S31803 (1.4462) Seamless and Welded Duplex Stainless Steel Tube is a high-performance corrosion-resistant steel tube designed for demanding industrial applications. It is manufactured from duplex stainless steel (austenitic-ferritic structure), offering excellent strength, pitting resistance, and stress corrosion cracking resistance. This product is available in both seamless and welded forms, with a controlled averange/ minimum wall thickness to ensure structural integrity under high-pressure and harsh environments. It is widely used in oil & gas, chemical processing, desalination, and marine engineering.
1.Chemical & Mechanical Properties
| ASTM A789 UNS S31803 Chemical Composition (%) |
| C |
Mn |
P |
S |
Si |
Cr |
Ni |
Mo |
N |
| ≤ 0.030% |
≤ 2.00% |
≤ 0.030% |
≤ 0.020% |
≤ 1.00% |
21.0 - 23.0% |
4.5 - 6.5% |
2.5 - 3.5% |
0.08 - 0.20% |
Mechanical Properties
| Property |
Standard Value |
| Tensile Strength |
620 - 795 MPa |
| Yield Strength (0.2% offset) |
≥ 450 MPa |
| Elongation |
≥ 25% |
| Hardness (Brinell) |
≤ 32 HRC |
| (-46°C) Charpy V-notch (-46°C) |
≥40 J |
Key Mechanical Characteristics
- High Strength Characteristics
- Excellent Toughness
- Excellent Fatigue Performance
- Physical Properties
2. Key Adventages
- Superior Strength-to-Weight Ratio
High strength properties: Yield strength (≥450MPa) is twice that of 304 stainless steel, with tensile strength (620-795MPa) significantly exceeding conventional austenitic grades.
Weight reduction: Allows 20-30% material savings compared to standard stainless steels at equivalent pressure ratings.
-
Outstanding Corrosion Resistance
Dual protection: Synergistic effect of Cr(21-23%)+Mo(2.5-3.5%)+N(0.08-0.20%)
Specialized resistance: Chloride stress corrosion cracking, pitting/crevice corrosion (PREN≥35), acid media
Lower lifecycle cost: 40-60% savings vs nickel alloys, 2-3x service life vs 316L
Easy installation: Excellent weldability (no PWHT required), CTE similar to carbon steel (13.5×10⁻⁶/℃)
Wide temperature range: Stable performance from -50℃ to 300℃
Dual-phase benefits: Ferrite phase for strength + Austenite phase for toughness
3. Key Applications
Subsea pipelines, X-mas tree components, LNG heat exchangers
Reactors, crystallizers, pickling equipment
High-pressure RO vessels, brine heaters
Geothermal casings, hydrogen storage
Selection Guidance
- High-strength+corrosion resistance combo
- Chloride-containing media
- Weight-sensitive high-pressure systems
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