Stainless Steel CN3MN
ASTM CN3MN · UNS J94651
CN3MN (J94651, ASTM A351/A743) is a nitrogen-strengthened super-austenitic cast stainless steel — the higher-strength version of CN3M that keeps the base alloy's high-molybdenum resistance to sulfuric acid and chlorides.
Reference datasheet — CN3MN is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SA condition
CN3MN tempers and conditions
CN3MN is supplied in 3 conditions, soft to hard. SA is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed ≥1120 °C and water quenched | The only condition CN3MN castings are supplied in — required by ASTM A351/A743/A744 to dissolve σ/χ phases and restore full corrosion resistance. | 300 | 620 | 45 | 180 HB | 1.9 % IACS |
hot isostatically pressed then solution annealed and quenched | Specified for critical pressure-containing or subsea valve/pump bodies where microporosity must be closed for radiographic and fatigue quality. | 310 | 645 | 50 | 180 HB | 1.9 % IACS |
Centrifugally cast, solution annealed and quenched | Choose for cylindrical items (pipe spools, sleeves, liners) where the denser, more directionally solidified centrifugal structure gives slightly higher strength. | 320 | 650 | 42 | 190 HB | 1.9 % IACS |
What is CN3MN?
CN3MN (J94651, ASTM A351/A743) is a nitrogen-strengthened super-austenitic cast stainless steel — the higher-strength version of CN3M that keeps the base alloy's high-molybdenum resistance to sulfuric acid and chlorides. It is chosen for solution-annealed, SA-HIP and centrifugally cast pump and valve components, with 300 MPa yield, 620 MPa tensile, 45 % elongation and 180 HB (90 HRB) in the default condition. Limits are a maximum service temperature of 425 °C, low machinability from strong work hardening, and the need for over-alloyed Ni-base filler when welding. CN3M is the nearest alternative where the extra strength is not required. CN3MN has a density of 8.06 g/cm³ (0.291 lb/in³), heavier than 98% of stainless steel grades. It melts at 1,320°C (2,408 °F). CN3MN has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
What is CN3MN used for?
- chemical pumps
- acid transfer valves
- corrosive slurry handling components
Advantages
- Good corrosion resistance — 88/100, better than 97% of stainless steel grades
- Tough — resists crack growth — 200 MPa·√m (182 ksi·√in), better than 86% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Poor heat conductor — 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades
- Low electrical conductivity — 1.9 % IACS, worse than 84% of stainless steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 77% of stainless steel grades
CN3MN properties
Typical room-temperature values for CN3MN-SA; bars are the position among stainless steel grades.
Physical3
CN3MN has a density of 8.06 g/cm³ (0.291 lb/in³), heavier than 98% of stainless steel grades. It melts at 1,320°C (2,408 °F).
Mechanical16
CN3MN has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
CN3MN is rated for continuous service to 425°C (797 °F). It conducts heat at 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades. Thermal expansion is 15.2 µm/m·K (8.44 µin/in·°F).
Electrical3
CN3MN conducts electricity at 1.9 % IACS, worse than 84% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 97% of stainless steel grades.
Sustainability4
Producing a kilogram of CN3MN takes about 75 MJ of energy and emits 5.5 kg of CO₂ — more than 84% of stainless steel grades. Typical recycled content is 65%.
Manufacturability7
CN3MN's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability very good (70/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. CN3MN is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CN3MN
Is CN3MN easy to machine?
Very gummy and strongly work-hardening — use rigid setups, sharp positive-rake carbide or coated inserts, heavy positive feed (never dwell), low-to-moderate speed and copious high-pressure coolant.
Can CN3MN be welded?
Readily welded by GTAW/GMAW/SMAW using overalloyed Ni-base filler (ERNiCrMo-3/alloy 625 or ERNiCrMo-4) to avoid Mo-depleted dendrite cores; keep interpass below ~150 °C, no preheat, no post-weld heat treatment except full re-solution if practical.
Can CN3MN be formed, bent or molded?
Supplied as castings — pour hot with generous risers and chills because the wide freezing range promotes centreline shrinkage; mandatory solution anneal at 1120–1150 °C followed by rapid water quench.
CN3MN 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 to avoid sensitisation | ≤ 0.03 | 0.02 |
| Mn | ≤ 2 | 1 |
| Si | ≤ 1 | 0.6 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.01 | 0.01 |
| Cr | 20 – 22 | 21 |
| Ni | 23.5 – 25.5 | 24.5 |
| Modrives PREN ≈ 45–48 | 6 – 7 | 6.5 |
| Nsolid-solution strengthening + pitting resistance | 0.18 – 0.26 | 0.22 |
| Cu | ≤ 0.75 | 0.3 |
| Fe | balance |
What surface finishes work on CN3MN?
Pickle and passivate (nitric-hydrofluoric) after welding or grinding to remove heat tint and restore the passive film; the alloy polishes to a bright non-magnetic finish and needs no coating in seawater service.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel CN3MN in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J94651
How much does CN3MN cost?
CN3MN is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
CN3MN — frequently asked
What is CN3MN used for?
CN3MN is typically used for chemical pumps, acid transfer valves and corrosive slurry handling components. In short: nitrogen-strengthened CN3M; high sulfuric-acid resistance; super-austenitic casting grade.
What is the yield strength of CN3MN?
CN3MN has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 68% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CN3MN easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Very gummy and strongly work-hardening — use rigid setups, sharp positive-rake carbide or coated inserts, heavy positive feed (never dwell), low-to-moderate speed and copious high-pressure coolant.
Can CN3MN be welded?
Yes — weldability is rated very good (70/100). Readily welded by GTAW/GMAW/SMAW using overalloyed Ni-base filler (ERNiCrMo-3/alloy 625 or ERNiCrMo-4) to avoid Mo-depleted dendrite cores; keep interpass below ~150 °C, no preheat, no post-weld heat treatment except full re-solution if practical.
What surface finishes work on CN3MN?
Pickle and passivate (nitric-hydrofluoric) after welding or grinding to remove heat tint and restore the passive film; the alloy polishes to a bright non-magnetic finish and needs no coating in seawater service.
Can CN3MN be formed, bent or molded?
Supplied as castings — pour hot with generous risers and chills because the wide freezing range promotes centreline shrinkage; mandatory solution anneal at 1120–1150 °C followed by rapid water quench.
What is the maximum service temperature of CN3MN?
CN3MN 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 CN3MN-SA and CN3MN CENT-SA?
SA is the default condition — the only condition CN3MN castings are supplied in — required by ASTM A351/A743/A744 to dissolve σ/χ phases and restore full corrosion resistance. CENT-SA: choose for cylindrical items (pipe spools, sleeves, liners) where the denser, more directionally solidified centrifugal structure gives slightly higher strength. Yield strength is 300 MPa in SA versus 320 MPa in CENT-SA.
How much does CN3MN cost?
CN3MN is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM International (2018)
- ASTM A743/A743M and A744/A744M — Corrosion-Resistant Iron-Chromium-Nickel Castings — ASTM International (2021)
- ASM Handbook Vol.1 — Cast Stainless Steels — ASM International (1990)
- Steel Castings Handbook, Supplement 8 — High Alloy Data Sheets, Corrosion Series — Steel Founders' Society of America (2004)
- AL-6XN Alloy (UNS N08367) data sheet — wrought analogue property reference — ATI (2020)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.