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CF8M castings: composition, properties and uses
CF8M is the cast form of 316 stainless steel: about 19% chromium, 10% nickel and 2 to 3% molybdenum, with 0.08% carbon maximum. It is specified in ASTM A351 for pressure parts and in A743 and A744 for corrosion-resistant service. It is the standard grade for pump casings, impellers and valve bodies in chloride and chemical duty.
Published 17 Oct 2026 · Updated 17 Oct 2026 · Ni-Chrome Alloy Castings
What is CF8M?
CF8M is the cast form of 316 stainless steel: about 19% chromium, 10% nickel and 2 to 3% molybdenum, with carbon held to 0.08% maximum. The letters follow the old Alloy Casting Institute code. C means corrosion-resistant service, F places it in the 19Cr-9Ni family, 8 is the carbon limit in hundredths of a percent, and M marks the molybdenum. It is the most common grade for pump casings, impellers and valve bodies in chemical, fertilizer and water duty.
What is the composition of CF8M?
The ranges below are the ASTM A351 limits for CF8M, in weight percent. Iron is the balance.
| Element | ASTM A351 CF8M, wt % |
|---|---|
| Carbon | 0.08 max |
| Chromium | 18.0 to 21.0 |
| Nickel | 9.0 to 12.0 |
| Molybdenum | 2.0 to 3.0 |
| Manganese | 1.50 max |
| Silicon | 1.50 max |
| Phosphorus | 0.040 max |
| Sulphur | 0.040 max |
Source: ASTM A351 grade CF8M as reproduced by Total Materia and Austral Alloys. A743 and A744 carry the same core ranges for CF8M; check the edition on your purchase order for silicon and residual limits.
The chromium range is wider and higher than wrought 316's 16 to 18%. That allowance covers segregation as the casting freezes, so the chromium stays high enough everywhere in the part.
What are the mechanical properties of CF8M?
ASTM A351 requires, at room temperature, a minimum tensile strength of 485 MPa, a minimum 0.2% yield strength of 205 MPa and a minimum elongation of 30%. Castings are supplied solution-treated: heated to at least 1,040 °C and quenched in water or cooled rapidly by other means. That treatment dissolves the chromium carbides that form during slow cooling in the mould, which is what keeps the grain boundaries corrosion-resistant.
Cast CF8M normally contains a little ferrite in its austenite. It helps the metal resist hot cracking as it solidifies and as it is welded. Specify a ferrite range only if your process or code calls for one.
What are the equivalents of CF8M?
- UNS: J92900.
- Wrought equivalent: 316 stainless.
- EN: 1.4408 (GX5CrNiMo19-11-2) is the usual match. Some datasheets name 1.4409, which is the low-carbon cast grade closer to CF3M. Check which one the drawing means.
- ASME: SA-351 CF8M for pressure parts.
- Australian Standard: AS 2074 H6B.
Which standard should you order CF8M to: A351, A743 or A744?
The grade is the same in all three. The standard decides what testing comes with it.
- ASTM A351 covers austenitic castings for pressure-containing parts: valve bodies, pump casings and fittings in piping systems. It carries the tensile requirements above and is the one most valve and pump codes reference.
- ASTM A743 covers corrosion-resistant castings for general application, such as impellers, wear rings and non-pressure parts.
- ASTM A744 covers corrosion-resistant castings for severe service, with extra requirements over A743.
If the part holds pressure, order A351. If it does not, A743 is normally enough. Use A744 when the process licensor or your own specification asks for it.
Where is CF8M used?
- Pump casings, impellers, diffusers and wear rings in chemical, fertilizer, desalination and water service.
- Valve bodies, bonnets, discs and trim.
- Process fittings, agitator parts and mixer components.
- Food, pharmaceutical and pulp-and-paper equipment where 316 is the wrought choice.
Cast SS316 is one of the grades in regular production at our foundry. Many of the enquiries we get are for replacements: a worn impeller or a cracked casing, with the old part or a drawing to work from.
How does CF8M fail in service?
- Pitting and crevice corrosion in chloride water. The molybdenum is there to resist it, which is why CF8M outlasts CF8 in seawater and brine, but warm, stagnant chloride still attacks it under deposits and gaskets.
- Intergranular corrosion when castings are not properly solution-treated, or after welding without a post-weld solution treatment. Chromium carbides form along the grain boundaries and the metal next to them corrodes. The low-carbon CF3M is the usual answer for parts that are welded and cannot be re-treated.
- Erosion-corrosion in impellers and casings that handle slurries or high-velocity flow. Here a harder grade, or a duplex, may last longer.
- Embrittlement of the ferrite after long exposure at moderately high temperature. CF8M is a wet-corrosion grade. For heat, use the H-series grades.
When should you choose CF8M over CF8 or CF3M?
Choose CF8M over CF8 when the fluid contains chlorides or reducing acids. Choose CF3M over CF8M when the part will be welded in service or in fabrication and cannot be solution-treated afterwards. For hot sulphuric acid, CN7M is the grade to ask about.
What should an RFQ for CF8M castings include?
- The standard and edition: A351, A743 or A744 CF8M, or EN 1.4408.
- The drawing, machining allowance and quantity.
- The fluid, its temperature and chloride content.
- Testing: chemistry, tensile, hydrostatic test if pressure-containing, radiography, dye penetrant, intergranular corrosion test if your code needs one.
- Third-party inspection and documentation format.
Our guide to getting a quote lists the rest.
CF8M questions
Is CF8M the same as SS316?
It is the cast counterpart of 316. The chemistry is close but not identical: CF8M allows more chromium and is made only as a casting, while 316 is the wrought grade for plate, bar and pipe.
Is CF8M magnetic?
Slightly, in most castings. The small amount of ferrite in the structure makes it weakly magnetic, which is normal and not a sign of the wrong grade.
What is the difference between CF8M and CF3M?
Carbon. CF3M is held to 0.03% maximum, which makes it far less prone to intergranular attack after welding. Order CF3M for parts that will be welded and not re-treated.