ASTM A217 Grade C12A
9Cr–1Mo–V martensitic alloy steel casting; the cast counterpart of Grade 91. A valve body material for supercritical power plants and high-temperature steam lines in refineries.
- Rp0.2 · MPa
- ≥ 415
- Rm · MPa
- 585–760
- TEMPERATURE
- ≤ +600 °C
- COST
Chemical composition
Mechanical properties
| STANDARD · CONDITION | Rp0.2 MPa | Rp1.0 MPa | Rm MPa | A % | KV J |
|---|---|---|---|---|---|
| ASTM A217 · C12A | 415 | — | 585–760 | 18 | — |
Room temperature, normalized + tempered. Z ≥ 45%, hardness ≤ 220 HBW.
Service temperature
Retains creep strength up to about 600 °C.
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 + tempering.
Media suitability GENERAL TREND
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 castings
- Thinner walls and a lighter body than WC9
- Good oxidation resistance at high temperature
Weaknesses
- Heat treatment and welding need very strict control (narrow tempering window)
- Preheating and post-weld heat treatment are mandatory
- Expensive, requires foundry experience
Manufacturing and use
- ECONOMY
- Medium to high.
- MANUFACTURING METHODS
- Sand casting + normalizing and tempering
- TYPICAL VALVE PARTS
- Body · Bonnet
Surface protection
- Wet paintIndustrial wet paint systemExternal surface; silicone-based heat-resistant paint is needed at high temperature
Source: ASTM A217. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.