Stainless Steel CF3MN-AC (Spheroidize annealed)
Heat-treated state
ASTM CF3MN · UNS J92804
Only for non-pressure, non-corrosive structural parts — not acceptable under ASTM A351/A743 for service castings.
Values for the AC condition
Other CF3MN tempers and conditions
CF3MN is listed in 3 conditions; see the grade overview at CF3MN.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed ≥1040 °C, water quenched | Standard supply condition for all pressure-containing CF3MN castings per ASTM A351/A743. | 290 | 550 | 45 | 170 HB | — |
hot isostatically pressed then solution annealed | Pick for thick-section or fatigue/impact-critical castings where shrinkage microporosity must be closed. | 295 | 565 | 50 | 170 HB | 2.2 % IACS |
ACThis page Spheroidize annealed | Only for non-pressure, non-corrosive structural parts — not acceptable under ASTM A351/A743 for service castings. | 300 | 530 | 25 | 180 HB | 2.2 % IACS |
What is CF3MN-AC?
CF3MN-AC is CF3MN heat treated to AC — only for non-pressure, non-corrosive structural parts — not acceptable under ASTM A351/A743 for service castings. CF3MN-AC has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 193 GPa (28 Msi). CF3MN-AC has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,385°C (2,525 °F). SA is the default condition FabDigit quotes; AC is available on request or by drawing note.
Limitations
- Limited formability — 15/100, worse than 91% of stainless steel grades
- Hard to polish — 60/100, worse than 80% of stainless steel grades
CF3MN-AC properties
Typical room-temperature values for CF3MN-AC; 22 are specific to this condition. Other listed values are CF3MN reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CF3MN-AC has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,385°C (2,525 °F).
Mechanical16
CF3MN-AC has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 25% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CF3MN-AC is rated for continuous service to 425°C (797 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), worse than 72% of stainless steel grades. Thermal expansion is 16 µm/m·K (8.89 µin/in·°F).
Electrical3
CF3MN-AC conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of CF3MN-AC takes about 53 MJ of energy and emits 4.5 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 80%.
Manufacturability8
CF3MN-AC's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability very good (75/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CF3MN-AC
Is CF3MN easy to machine?
Gummy and work-hardening from the nitrogen — use rigid setups, sharp positive-rake carbide, heavy positive feed and flood coolant; expect ~35% of 1212 speeds and interrupted cuts through the cast skin.
Can CF3MN be welded?
Readily welded by GTAW/GMAW/SMAW with ER316L or higher-Mo 316LMn/309LMo filler; no pre- or post-weld heat treatment required for corrosion, keep interpass below ~150 °C and heat input low to limit sigma/ferrite issues.
Can CF3MN be formed, bent or molded?
Sand or investment cast with generous risers on heavy sections; austenitic solidification shrinkage ~5–6% requires directional feeding, then solution treat above 1040 °C and water quench.
What surface finishes work on CF3MN?
Pickle and passivate (ASTM A967) or electropolish after grinding; anodizing is not applicable, and shot blasting should use stainless or ceramic media to avoid iron contamination.
CF3MN chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Clow carbon for as-welded intergranular resistance | ≤ 0.03 | 0.02 |
| Mn | ≤ 1.5 | 1 |
| Si | ≤ 1.5 | 1 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.04 | 0.02 |
| Cr | 17 – 21 | 19 |
| Ni | 9 – 13 | 11 |
| Mo | 2 – 3 | 2.5 |
| Nsolid-solution strengthening, defines the 'N' suffix | 0.1 – 0.2 | 0.15 |
| Fe | balance | — |
CF3MN-AC — frequently asked
What is CF3MN-AC used for?
CF3MN-AC is typically used for high-strength pressure castings, chemical process valves and marine components. In short: stronger cast 316L; nitrogen-strengthened CF3M; low-carbon weldability retained.
What is the yield strength of CF3MN-AC?
CF3MN-AC has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 68% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CF3MN-AC easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Gummy and work-hardening from the nitrogen — use rigid setups, sharp positive-rake carbide, heavy positive feed and flood coolant; expect ~35% of 1212 speeds and interrupted cuts through the cast skin.
Can CF3MN-AC be welded?
Yes — weldability is rated very good (75/100). Readily welded by GTAW/GMAW/SMAW with ER316L or higher-Mo 316LMn/309LMo filler; no pre- or post-weld heat treatment required for corrosion, keep interpass below ~150 °C and heat input low to limit sigma/ferrite issues.
What surface finishes work on CF3MN-AC?
Pickle and passivate (ASTM A967) or electropolish after grinding; anodizing is not applicable, and shot blasting should use stainless or ceramic media to avoid iron contamination.
Can CF3MN-AC be formed, bent or molded?
Sand or investment cast with generous risers on heavy sections; austenitic solidification shrinkage ~5–6% requires directional feeding, then solution treat above 1040 °C and water quench.
What is the maximum service temperature of CF3MN-AC?
CF3MN-AC is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CF3MN-SA and CF3MN-AC?
SA is the default condition — standard supply condition for all pressure-containing CF3MN castings per ASTM A351/A743. AC: only for non-pressure, non-corrosive structural parts — not acceptable under ASTM A351/A743 for service castings. Yield strength is 290 MPa in SA versus 300 MPa in AC.
Sources
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM International (2018)
- ASTM A743/A743M — Castings, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (cast corrosion-resistant steels) — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.