ASTM A213 T911 Seamless Ferritic Alloy Steel Tube (UNS K90911)
ASTM A213 T911 Seamless Ferritic Alloy Steel Tubes are advanced-grade, high-performance tubes engineered for elevated-temperature, high-pressure boiler and power plant applications. Designed as an improved version of Grade T91, Grade T911 offers enhanced creep strength, higher durability, better weldability, and improved microstructural stability.
With outstanding resistance to oxidation and thermal fatigue, ASTM A213 T911 (UNS K90911) tubes are widely used in superheaters, reheaters, ultra-supercritical boilers, and thermal power generation systems.
Key Features
- Enhanced creep & rupture strength vs. T91
- Superior oxidation & corrosion resistance
- High microstructural stability in long-term high-temperature exposure
- Designed for ultra-supercritical plant temperatures
- Excellent resistance to thermal fatigue
- Improved weldability & toughness
- Seamless construction for pressure-critical applications
Equivalent Grades
| Standard |
Equivalent Grade |
| UNS |
K90911 (Industry Reference) |
| ASME |
SA213 T911 |
| EN |
X12CrMoWVNbN10-1-1 |
| DIN |
1.4907 |
| BS |
Grade 911 Alloy Steel |
Available Sizes
| Category |
Range |
| Outside Diameter |
6 mm – 120 mm |
| Wall Thickness |
0.5 mm – 16 mm |
| Length |
Up to 12 meters (custom cut lengths available) |
ASTM A213 T911 Chemical Composition
| Element |
Percentage (%) |
| Carbon (C) |
0.08 – 0.12 |
| Manganese (Mn) |
0.30 – 0.60 |
| Phosphorus (P) |
≤ 0.020 |
| Sulfur (S) |
≤ 0.010 |
| Silicon (Si) |
0.20 – 0.50 |
| Chromium (Cr) |
8.5 – 9.5 |
| Molybdenum (Mo) |
0.85 – 1.05 |
| Tungsten (W) |
1.50 – 2.00 |
| Vanadium (V) |
0.18 – 0.25 |
| Niobium (Nb) |
0.06 – 0.10 |
| Nitrogen (N) |
0.03 – 0.07 |
| Boron (B) |
0.001 – 0.005 |
| Iron (Fe) |
Balance |
ASTM A213 T911 Mechanical Properties
| Property |
Value |
| Tensile Strength (min) |
620 MPa |
| Yield Strength (min) |
440 MPa |
| Elongation |
20% |
| Hardness (HBW) |
≤ 250 |
| Creep Resistance |
Significantly higher vs. T91 |
| Impact Toughness |
High at elevated temperatures |
Physical Properties
| Property |
Value |
| Density |
7.80 g/cm³ |
| Melting Point |
~1400–1520°C |
| Thermal Conductivity |
23–24 W/m·K |
| Coefficient of Expansion |
11.5 × 10⁻⁶ /°C |
| Modulus of Elasticity |
215 GPa |
Types of ASTM A213 T911 Ferritic Alloy Steel Tubes
- Seamless Boiler Tubes
- Superheater Tubes
- Reheater Tubes
- Heat Exchanger Tubes
- High-Pressure Tubes
- Cold Drawn Seamless Tubes
- Hot Finished Tubes
- U-Bend Tubes
- Custom-Fabricated Tubes
Applications
- Ultra-Supercritical Power Plants
- High-Pressure Boilers
- Superheaters & Reheaters
- Steam Generators
- Heat Exchangers
- Petrochemical Plants
- Oil & Gas Refineries
- Thermal & Nuclear Power Plants
- Chemical Processing Units
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