ASTM A351 Grade CF8
Molybdenum-free austenitic stainless casting; the cast counterpart of 304. An economical stainless body material for fresh water, food and mildly chemical service.
- Rp0.2 · MPa
- ≥ 205
- Rm · MPa
- ≥ 485
- TEMPERATURE
- −196 … +538 °C
- COST
Chemical composition
%, single values are maximums. The Si limit is higher than for CF8M (2.00).
Mechanical properties
| STANDARD · CONDITION | Rp0.2 MPa | Rp1.0 MPa | Rm MPa | A % | KV J |
|---|---|---|---|---|---|
| ASTM A351 · CF8 | 205 | — | ≥ 485 | 35 | — |
ASME B16.34 pressure-temperature ratings
| CLASS · bar | −29 … 38 °C | 100 °C | 200 °C | 300 °C | 400 °C | 500 °C |
|---|---|---|---|---|---|---|
| Class 150 | 19.0 | 15.7 | 13.2 | 10.2 | 6.5 | 2.8 |
| Class 300 | 49.6 | 40.9 | 35.4 | 30.9 | 28.4 | 26.5 |
| Class 600 | 99.3 | 81.7 | 69.0 | 61.8 | 56.9 | 53.0 |
| Class 900 | 148.9 | 122.6 | 103.4 | 92.7 | 85.3 | 79.5 |
| Class 1500 | 248.2 | 204.3 | 172.4 | 154.6 | 142.2 | 132.4 |
| Class 2500 | 413.7 | 340.4 | 287.3 | 257.6 | 237.0 | 220.7 |
Standard class, bar. Material group: CF8/CF3. Greyed values are outside the material's service range (−196 … +538 °C). Flanged-end ratings end at 538 °C.
Service temperature
For flanged-end valves, ASME B16.34 ratings end at 538 °C; above 425 °C, C ≥ 0.04% is specified.
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
- Solution annealing ≥ 1040 °C, rapid cooling.
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
- Economical stainless casting
- Suitable for cryogenic service
- Easy to cast and weld
Weaknesses
- Low chloride resistance (no molybdenum)
- Risk of sensitization in welding: CF3 is preferred for welded construction
Manufacturing and use
- ECONOMY
- Low to medium.
- MANUFACTURING METHODS
- Sand casting · Investment casting
- TYPICAL VALVE PARTS
- Body · Bonnet · Disc
Source: ASTM A351. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.