ASTM A182 GRADE F11 LOW-ALLOY STEEL — TECHNICAL DATASHEET AND ENGINEERING REPORT
ASTM A182 Grade F11 is a high-performance, low-alloy ferritic steel widely specified for the manufacture of forged flanges, fittings, valves, and other pressure-containing components intended for elevated-temperature and corrosive service. Bridging the operational gap between basic carbon steels and high-alloy stainless steels, Grade F11 leverages chromium and molybdenum additions to retain mechanical strength and resist creep deformation at continuous operating temperatures up to 480°C (900°F) and short-term exposures up to 550°C (1020°F).
The grade features deliberate silicon addition (0.50% - 1.00%), classifying it as a silicon-modified grade that provides elevated-temperature tensile strength and excellent scaling resistance in high-temperature air and steam atmospheres.
■ Global Standards and Equivalency
ASTM A182 F11 is divided into three classes (Class 1, 2, and 3) to accommodate varying strength and ductility requirements across pressure vessel and piping codes.
| ASTM Grade | UNS Designation | EN / DIN Standard | British (BS) / JIS Standard | Casting Equivalent |
|---|---|---|---|---|
| F11 Class 1 | K11597 | 1.7335 / 13CrMo4-5 | 3604 Gr. 11 / SCMV3 | ASTM A217 WC6 |
| F11 Class 2 | K11572 | 1.7335 / 13CrMo4-5 | 3604 Gr. 11 / SCMV3 | ASTM A217 WC6 |
| F11 Class 3 | K11572 | 1.7335 / 13CrMo4-5 | 3604 Gr. 11 / SCMV3 | ASTM A217 WC6 |
■ Chemical Composition Limits (wt%)
Chemical composition is tightly regulated to balance hardenability, weldability, and mechanical stability. Classes 2 and 3 permit higher carbon limits to achieve greater strength.
| Element | Class 1 (UNS K11597) | Class 2 & Class 3 (UNS K11572) |
|---|---|---|
| Carbon (C) | 0.05 – 0.15 | 0.10 – 0.20 |
| Manganese (Mn) | 0.30 – 0.60 | 0.30 – 0.80 |
| Phosphorus (P) | 0.030 max | 0.040 max |
| Sulfur (S) | 0.030 max | 0.040 max |
| Silicon (Si) | 0.50 – 1.00 | 0.50 – 1.00 |
| Chromium (Cr) | 1.00 – 1.50 | 1.00 – 1.50 |
| Molybdenum (Mo) | 0.44 – 0.65 | 0.44 – 0.65 |
| Nickel (Ni) | — | 0.40 max |
■ Proprietary Datasheet Download
ASTM A182 Grade F11 — Complete Technical Yield & Tolerance Datasheet
Contains empirical data for stress simulations, full thermal expansion charts, and advanced piping configuration tables. Corporate/engineering credentials required.
⬇ DOWNLOAD DATASHEET■ Minimum Mechanical Properties (Room Temperature)
The mechanical performance relies heavily on the final heat treatment state: annealed (Class 1) versus normalized and tempered (Classes 2 & 3).
| Mechanical Property | Class 1 (Annealed) | Class 2 (N & T) | Class 3 (N & T) |
|---|---|---|---|
| Tensile Strength, min | 60 ksi [415 MPa] | 70 ksi [485 MPa] | 75 ksi [515 MPa] |
| Yield Strength, min | 30 ksi [205 MPa] | 40 ksi [275 MPa] | 45 ksi [310 MPa] |
| Elongation in 2 in. / 50mm | 20% | 20% | 20% |
| Reduction of Area | 45% | 30% | 30% |
| Brinell Hardness (HBW) | 121 – 174 | 143 – 207 | 156 – 207 |
■ Physical and Thermophysical Characteristics
Grade F11 is a strongly ferromagnetic low-alloy steel. Its density is approximately 7.85 g/cm³ with a melting range of 1371°C to 1480°C (2500°F to 2700°F). Relevant high-temperature properties used for thermodynamic calculations are abbreviated below:
| Temperature | Mean Thermal Expansion (10⁻⁶ mm/mm·°C) |
Thermal Conductivity (W/m·°C) |
Modulus of Elasticity (10³ MPa) |
|---|---|---|---|
| 20°C (68°F) | 11.5 | 41.0 | 204 |
| 200°C (392°F) | 12.7 | 40.1 | 193 |
| 400°C (752°F) | 13.8 | 36.8 | 179 |
| 600°C (1112°F) | 14.8 | 32.8 | 157 |
■ ASME B16.5 Pressure-Temperature Ratings (Class 150)
As temperatures rise, the allowable working pressure drops significantly due to yield strength reduction and the onset of creep.
| Service Temp (°F) | Service Temp (°C) | Max Allowable Working Pressure (psig) |
|---|---|---|
| -20 to 100 | -29 to 38 | 290 |
| 400 | 204 | 200 |
| 600 | 316 | 140 |
| 800 | 427 | 80 |
| 1000 | 538 | 20 |
■ Welding, Preheat, and PWHT Specifications
Grade F11 exhibits strong air-hardening tendencies. Rapid cooling rates promote hard, brittle acicular martensite, demanding strict thermal controls during welding.
| Parameter | Specification Criteria | Metallurgical Objective |
|---|---|---|
| ASME Group / P-Number | P-No. 4, Group 1 | Classifies low-alloy steels (1% ≤ Cr ≤ 2%). |
| Filler Metal | AWS A5.28 ER80S-B2 | Matches the 1.25% Cr - 0.5% Mo base chemistry. |
| Minimum Preheat Temp. | 150°C - 200°C (300°F - 400°F) | Retards cooling to prevent martensite formation. |
| PWHT Temperature Range | 650°C - 705°C (1200°F - 1300°F) | Relieves residual stresses and restores ductility. |
| Hardness Limit (NACE) | 22 HRC max (237 HBW max) | Prevents sulfide stress cracking in sour service. |
■ Engineering Recommendations and Service Guidelines
- Material Selection Limits: Specify Grade F11 for temperatures between 370°C (700°F) and 550°C (1020°F). For higher temperatures, upgrade to F22 or F91 for superior creep and oxidation resistance.
- Sour Service Compliance: Enforce a maximum hardness limit of 22 HRC (237 HBW) via controlled Post-Weld Heat Treatment (PWHT) to comply with NACE MR0175/ISO 15156-2.
- Environmental Restrictions: F11 has low overall chromium. Avoid unclad use in stagnant, high-salinity, or poor air-circulation environments where it may suffer localized pitting or stress corrosion cracking.
- Thermodynamic Design: Always utilize temperature-dependent thermal expansion, conductivity, and elastic modulus values for hot-system analyses, as ambient values will cause significant engineering miscalculations.
