Stainless Steel CG6MMN
ASTM CG6MMN · UNS J93790
CG6MMN (J93790) is a nitrogen-strengthened manganese-molybdenum cast austenitic stainless steel, the casting counterpart of wrought Nitronic-type alloys, reaching 350 MPa yield, 655 MPa tensile strength, 40% elongation and 190 HB (91 HRB) after solution annealing.
Reference datasheet — CG6MMN 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
CG6MMN tempers and conditions
CG6MMN 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 (≥1040 °C, water quenched) per ASTM A351/A743 | Standard supplied condition for all pressure-containing CG6MMN castings; maximum corrosion resistance and full N-strengthened ductility. | 350 | 655 | 40 | 190 HB | — |
As fabricated | Only for non-code, non-corrosive service; retained interdendritic carbides/nitrides and residual ferrite reduce ductility and corrosion resistance. | 360 | 620 | 22 | 14 HRC | 2.2 % IACS |
hot isostatically pressed then solution annealed | Choose for critical pump/valve castings where internal microporosity must be closed to raise fatigue life and NDE acceptance. | 365 | 690 | 45 | 190 HB | 2.3 % IACS |
What is CG6MMN?
CG6MMN (J93790) is a nitrogen-strengthened manganese-molybdenum cast austenitic stainless steel, the casting counterpart of wrought Nitronic-type alloys, reaching 350 MPa yield, 655 MPa tensile strength, 40% elongation and 190 HB (91 HRB) after solution annealing. It combines the highest strength in this cast family with a corrosion resistance score of 75, which suits high-pressure pump and valve castings and marine hardware; it is also supplied HIP plus solution annealed and as-cast. Service is limited to 650 °C and the alloy work-hardens strongly, so machining is slow (15–25 m/min turning); CG8M is the easier alternative when the extra strength is not needed. CG6MMN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 59% of stainless steel grades. It melts at 1,385°C (2,525 °F). CG6MMN has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 52% of stainless steel grades. Elongation at break is 40% and the elastic modulus is 193 GPa (28 Msi).
What is CG6MMN used for?
- High-strength pump and valve castings
- Marine and offshore components
- Seawater pump casings and impellers
- Pressure-retaining valve bodies and bonnets
- Subsea and deck hardware castings
- Shaft sleeves and wear rings
- Hygienic process equipment castings
Advantages
- Good corrosion resistance — 75/100, better than 79% of stainless steel grades
Limitations
- Poor heat conductor — 13 W/m·K (7.51 BTU/hr·ft·°F), worse than 85% of stainless steel grades
CG6MMN properties
Typical room-temperature values for CG6MMN-SA; bars are the position among stainless steel grades.
Physical3
CG6MMN has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 59% of stainless steel grades. It melts at 1,385°C (2,525 °F).
Mechanical15
CG6MMN has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 52% of stainless steel grades. Elongation at break is 40% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
CG6MMN is rated for continuous service to 650°C (1,202 °F). It conducts heat at 13 W/m·K (7.51 BTU/hr·ft·°F), worse than 85% of stainless steel grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
CG6MMN conducts electricity at 2.3 % IACS, better than 55% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (75/100), better than 79% of stainless steel grades.
Sustainability4
Producing a kilogram of CG6MMN takes about 55 MJ of energy and emits 4.3 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 70%.
Manufacturability8
CG6MMN's machinability is poor (30/100, worse than 70% 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. CG6MMN is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CG6MMN
Is CG6MMN easy to machine?
Tough and strongly work-hardening — use rigid setups, positive-rake carbide, heavy depth of cut, 15–25 m/min for turning and flood coolant; never dwell or take spring passes.
Can CG6MMN be welded?
Readily welded by GTAW/SMAW with matching CG6MMN or E209/ER209 (or 22Cr-N) filler; keep interpass low, no preheat, and re-solution-anneal heavily welded pressure castings.
Can CG6MMN be formed, bent or molded?
Sand or investment casting with tight nitrogen and ferrite control; provide generous risers and rapid solidification, and always solution treat ≥1040 °C with water quench.
CG6MMN 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 |
|---|---|---|
| C | ≤ 0.06 | 0.05 |
| Mn | 4 – 6 | 5 |
| Si | ≤ 1 | 0.6 |
| P | ≤ 0.04 | 0.03 |
| S | ≤ 0.03 | 0.02 |
| Cr | 20.5 – 23.5 | 22 |
| Ni | 11.5 – 13.5 | 12.5 |
| Mo | 1.5 – 3 | 2.2 |
| Nnitrogen strengthening | 0.1 – 0.3 | 0.2 |
| Nblisted as Cb in ASTM | 0.1 – 0.3 | 0.2 |
| V | 0.1 – 0.3 | 0.2 |
| Fe | balance |
What surface finishes work on CG6MMN?
Pickle and passivate per ASTM A380 after grinding/welding; electropolish for hygienic service — no anodizing, and mechanical finishing is limited by casting skin soundness.
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 CG6MMN in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J93790
- Also called
- Cast Nitronic 50
How much does CG6MMN cost?
CG6MMN 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.
CG6MMN — frequently asked
What is CG6MMN used for?
CG6MMN is typically used for high-strength pump and valve castings, marine and offshore components, seawater pump casings and impellers, pressure-retaining valve bodies and bonnets, subsea and deck hardware castings and shaft sleeves and wear rings. In short: strongest cast austenitic here; nitrogen-strengthened marine grade; slow to machine.
What is the yield strength of CG6MMN?
CG6MMN has a typical yield strength of 350 MPa (50.8 ksi) and a tensile strength of 655 MPa (95 ksi) — weaker than 52% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is CG6MMN easy to machine?
Not especially — machinability is rated poor (30/100, worse than 70% of stainless steel grades). Tough and strongly work-hardening — use rigid setups, positive-rake carbide, heavy depth of cut, 15–25 m/min for turning and flood coolant; never dwell or take spring passes.
Can CG6MMN be welded?
Yes — weldability is rated very good (70/100). Readily welded by GTAW/SMAW with matching CG6MMN or E209/ER209 (or 22Cr-N) filler; keep interpass low, no preheat, and re-solution-anneal heavily welded pressure castings.
What surface finishes work on CG6MMN?
Pickle and passivate per ASTM A380 after grinding/welding; electropolish for hygienic service — no anodizing, and mechanical finishing is limited by casting skin soundness.
Can CG6MMN be formed, bent or molded?
Sand or investment casting with tight nitrogen and ferrite control; provide generous risers and rapid solidification, and always solution treat ≥1040 °C with water quench.
What is the maximum service temperature of CG6MMN?
CG6MMN is rated for continuous use to about 650°C (1,202 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CG6MMN-SA and CG6MMN-F?
SA is the default condition — standard supplied condition for all pressure-containing CG6MMN castings; maximum corrosion resistance and full N-strengthened ductility. F: only for non-code, non-corrosive service; retained interdendritic carbides/nitrides and residual ferrite reduce ductility and corrosion resistance. Yield strength is 350 MPa in SA versus 360 MPa in F.
How much does CG6MMN cost?
CG6MMN 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 — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (cast stainless steels) — ASM International (1990)
- Steel Castings Handbook — Steel Founders' Society of America / ASM (1995)
- Nitronic 50 / 22Cr-13Ni-5Mn (UNS S20910) alloy data — AK Steel / Armco (Universal Stainless) (2015)
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.