Stainless Steel CN3M
ASTM CN3M · UNS J94652
CN3M (UNS J94652) is a low-carbon, high-nickel, high-molybdenum cast austenitic stainless steel specified to ASTM A351/A743/A744, and is the cast counterpart to wrought Alloy 20.
Reference datasheet — CN3M 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
CN3M tempers and conditions
CN3M 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 | Standard as-supplied condition for all A743/A744 CN3M castings; maximum corrosion resistance and ductility. | 220 | 500 | 45 | 155 HB | 1.7 % IACS |
Hot isostatically pressed + solution annealed | Specified for pressure-retaining or radiographically critical parts where microshrinkage must be closed; gives the best fatigue and impact values. | 230 | 520 | 50 | 160 HB | 1.7 % IACS |
Centrifugally cast (A351 CN3M), solution annealed | Choose for tubes, sleeves and rings where the denser, finer-grained centrifugal structure gives slightly higher strength and better soundness. | 250 | 540 | 42 | 165 HB | 1.7 % IACS |
Supply forms, finishes and certifications
Ways CN3M is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
A744 | Severe corrosion service castings | Certification |
What is CN3M?
CN3M (UNS J94652) is a low-carbon, high-nickel, high-molybdenum cast austenitic stainless steel specified to ASTM A351/A743/A744, and is the cast counterpart to wrought Alloy 20. It is selected for severe sulfuric acid and chloride service, with a corrosion resistance score of 82 and typical properties of 220 MPa yield, 500 MPa tensile, 45 % elongation and 155 HB; supplied as SA, SA-CENT, SA-HIP and A744 castings. Maximum service temperature is 425 °C, the alloy is gummy to machine, and the fully austenitic weld metal is hot-crack sensitive. CF3M is the lower-alloy, lower-cost alternative for less aggressive acids. CN3M has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,370°C (2,498 °F). CN3M has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 99% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 193 GPa (28 Msi).
What is CN3M used for?
- chemical process pumps
- valves
- sulfuric acid handling equipment
- acid pickling components
Advantages
- Good corrosion resistance — 82/100, better than 90% of stainless steel grades
- Tough — resists crack growth — 190 MPa·√m (172.9 ksi·√in), better than 77% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- Low strength — 220 MPa (31.9 ksi), worse than 99% of stainless steel grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% of stainless steel grades
- Poor heat conductor — 12.5 W/m·K (7.22 BTU/hr·ft·°F), worse than 90% of stainless steel grades
- Limited formability — 20/100, worse than 86% of stainless steel grades
- High embodied carbon — 5.6 kg CO₂/kg, worse than 83% of stainless steel grades
CN3M properties
Typical room-temperature values for CN3M-SA; bars are the position among stainless steel grades.
Physical3
CN3M has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical15
CN3M has a yield strength of 220 MPa (31.9 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 99% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CN3M is rated for continuous service to 425°C (797 °F). It conducts heat at 12.5 W/m·K (7.22 BTU/hr·ft·°F), worse than 90% of stainless steel grades. Thermal expansion is 14.8 µm/m·K (8.22 µin/in·°F).
Electrical3
CN3M conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 90% of stainless steel grades.
Sustainability4
Producing a kilogram of CN3M takes about 72 MJ of energy and emits 5.6 kg of CO₂ — more than 83% of stainless steel grades. Typical recycled content is 65%.
Manufacturability8
CN3M's machinability is poor (30/100, worse than 70% of stainless steel grades); weldability good (55/100); formability poor (20/100).
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. CN3M is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CN3M
Is CN3M easy to machine?
Gummy and strongly work-hardening — use rigid setups, positive-rake carbide, heavy feeds, low-to-moderate speeds and flood coolant; never dwell or rub.
Can CN3M be welded?
Weld with matching Alloy 20Cb-3/E320LR or overmatched Ni-base filler; fully austenitic weld metal is hot-crack prone, so keep heat input and interpass temperature low and avoid restraint.
Can CN3M be formed, bent or molded?
Casting-only grade — gate and feed generously for the wide freezing range, and solution anneal above 1120 °C with water quench after all major weld repairs.
CN3M 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 intergranular corrosion resistance | ≤ 0.03 | 0.02 |
| Mn | ≤ 2 | 1 |
| Si | ≤ 1 | 0.7 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Cr | 20 – 22 | 21 |
| Nistabilises fully austenitic structure, resists acid SCC | 23 – 27 | 25 |
| Mopitting/crevice resistance, PREN≈36–38 | 4.5 – 5.5 | 5 |
| Fe | balance |
What surface finishes work on CN3M?
Passivate (ASTM A967) or electropolish after descaling; no anodizing — pickling with nitric-HF must be followed by thorough rinsing.
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 CN3M in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J94652
How much does CN3M cost?
CN3M 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.
CN3M — frequently asked
What is CN3M used for?
CN3M is typically used for chemical process pumps, valves, sulfuric acid handling equipment and acid pickling components. In short: cast Alloy 20 equivalent; best acid resistance here; sulfuric acid service castings.
What is the yield strength of CN3M?
CN3M has a typical yield strength of 220 MPa (31.9 ksi) and a tensile strength of 500 MPa (72.5 ksi) — weaker than 99% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CN3M easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Gummy and strongly work-hardening — use rigid setups, positive-rake carbide, heavy feeds, low-to-moderate speeds and flood coolant; never dwell or rub.
Can CN3M be welded?
Yes — weldability is rated good (55/100). Weld with matching Alloy 20Cb-3/E320LR or overmatched Ni-base filler; fully austenitic weld metal is hot-crack prone, so keep heat input and interpass temperature low and avoid restraint.
What surface finishes work on CN3M?
Passivate (ASTM A967) or electropolish after descaling; no anodizing — pickling with nitric-HF must be followed by thorough rinsing.
Can CN3M be formed, bent or molded?
Casting-only grade — gate and feed generously for the wide freezing range, and solution anneal above 1120 °C with water quench after all major weld repairs.
What is the maximum service temperature of CN3M?
CN3M 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 CN3M-SA and CN3M SA-CENT?
SA is the default condition — standard as-supplied condition for all A743/A744 CN3M castings; maximum corrosion resistance and ductility. SA-CENT: choose for tubes, sleeves and rings where the denser, finer-grained centrifugal structure gives slightly higher strength and better soundness. Yield strength is 220 MPa in SA versus 250 MPa in SA-CENT.
How much does CN3M cost?
CN3M 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 A743/A743M — Castings, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2021)
- ASTM A744/A744M — Castings, Iron-Chromium-Nickel, Corrosion Resistant, for Severe Service — ASTM International (2021)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM International (2018)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Cast Stainless Steels) — ASM International (1990)
- ASM Specialty Handbook: Stainless Steels — ACI cast alloy designations and properties — ASM International (1994)
- Steel Founders' Society of America — High Alloy Data Sheets, Corrosion Series — SFSA (2004)
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.