Carbon and alloy steel · forged
F91
ASTM A182 Grade F91 · 9Cr–1Mo–V
Modified 9Cr–1Mo–V martensitic steel. The forged body and flange material for steam lines around 600 °C in supercritical power plants.
- Rp0.2 · MPa
- ≥ 415
- Rm · MPa
- 585–760
- TEMPERATURE
- −29 … +649 °C
- COST
Chemical composition
The values in this section are being verified.
Mechanical properties
| STANDARD · CONDITION | Rp0.2 MPa | Rp1.0 MPa | Rm MPa | A % | KV J |
|---|---|---|---|---|---|
| ASTM A182 · F91 | 415 | — | 585–760 | 20 | — |
Room temperature. Z ≥ 40%, hardness ≤ 248 HBW.
Service temperature
−29 °C+649 °C−200−1000100200300400500600700800
This is the limit of the material itself. A valve's service temperature is usually set by the seal and seat materials; product pages give it for each seal option.
Physical properties and heat treatment
- HEAT TREATMENT
- Normalizing 1040–1080 °C + tempering 730–800 °C (Project Materials).
Media suitability GENERAL TREND
Fresh water
Seawater
Steam
Hydrocarbons, oil
Dilute acid
Caustic
Air, gas
Low temperature
Emsal assessment. The final choice is made from corrosion tables, taking concentration, temperature, chloride content and flow velocity into account.
Strengths and weaknesses
Strengths
- The highest creep strength among Cr-Mo steels
- Thin walls, low thermal stress
Weaknesses
- Heat treatment and welding need very strict control
- Expensive
Manufacturing and use
- ECONOMY
- Medium to high.
- MANUFACTURING METHODS
- Forging + normalizing and tempering
- TYPICAL VALVE PARTS
- Forged body · Flange
Surface protection
- Wet paintIndustrial wet paint systemExternal surface; silicone-based heat-resistant paint is needed at high temperature
Source: ASTM A182. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.