Nickel Alloy CW-6MC
UNS N26625, J26625 · ASTM A494 CW6MC
CW-6MC is the cast Ni-Cr-Mo-Nb grade of ASTM A494 (UNS N26625/J26625), chemically close to wrought Alloy 625, with molybdenum and niobium giving solid-solution strength and resistance to pitting and crevice corrosion.
Reference datasheet — CW-6MC 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
CW-6MC tempers and conditions
CW-6MC is supplied in 4 conditions, soft to hard. SA is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SADefault Solution annealed (≈1120 °C, water quenched), ASTM A494 supply condition | Standard delivery condition for A494 CW-6MC castings: dissolves interdendritic carbides/Laves for maximum corrosion resistance and ductility. | 315 | 550 | 40 | 180 HB | — |
hot isostatically pressed then solution annealed | Choose for fatigue- or pressure-critical castings: HIP closes microporosity, giving higher ductility and more consistent fatigue life. | 320 | 575 | 46 | 180 HB | 1.3 % IACS |
Weld-repaired casting, re-solution annealed after repair | Foundry-repaired castings (ERNiCrMo-3 filler) re-solution treated to restore corrosion performance in the repair zone. | 320 | 540 | 35 | 185 HB | 1.3 % IACS |
Spheroidize annealed | Only for non-critical or low-corrosivity duty — interdendritic Nb-rich Laves/carbides lower ductility and localized corrosion resistance. | 350 | 520 | 22 | 14 HRC | 1.3 % IACS |
What is CW-6MC?
CW-6MC is the cast Ni-Cr-Mo-Nb grade of ASTM A494 (UNS N26625/J26625), chemically close to wrought Alloy 625, with molybdenum and niobium giving solid-solution strength and resistance to pitting and crevice corrosion. Solution-annealed castings provide 315 MPa yield, 550 MPa tensile, 40 % elongation and about 180 HB (89 HRB), with service to 900 °C; typical forms are sand and investment cast valve bodies, pump casings and fittings. It is one of the few high-alloy castings that welds readily, but it work hardens and machines slowly, and cost is high. For reducing acids such as hydrochloric, cast CW-12MW (Alloy C-276) is the closer choice. CW-6MC has a density of 8.44 g/cm³ (0.305 lb/in³), heavier than 60% of nickel alloy grades. It melts at 1,290°C (2,354 °F). CW-6MC has a yield strength of 315 MPa (45.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 70% of nickel alloy grades. Elongation at break is 40% and the elastic modulus is 200 GPa (29 Msi).
What is CW-6MC used for?
- Valve trim castings
- Pump casings for sour service
- Marine casting components
Advantages
- Good corrosion resistance — 90/100, better than 85% of nickel alloy grades
- Readily welded — 85/100, better than 83% of nickel alloy grades
Limitations
- Poor heat conductor — 9.8 W/m·K (5.66 BTU/hr·ft·°F), worse than 92% of nickel alloy grades
- Limited formability — 20/100, worse than 75% of nickel alloy grades
CW-6MC properties
Typical room-temperature values for CW-6MC-SA; bars are the position among nickel alloy grades.
Physical3
CW-6MC has a density of 8.44 g/cm³ (0.305 lb/in³), heavier than 60% of nickel alloy grades. It melts at 1,290°C (2,354 °F).
Mechanical14
CW-6MC has a yield strength of 315 MPa (45.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 70% of nickel alloy grades. Elongation at break is 40% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CW-6MC is rated for continuous service to 900°C (1,652 °F). It conducts heat at 9.8 W/m·K (5.66 BTU/hr·ft·°F), worse than 92% of nickel alloy grades. Thermal expansion is 12.8 µm/m·K (7.11 µin/in·°F).
Electrical3
CW-6MC conducts electricity at 1.3 % IACS, worse than 89% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 85% of nickel alloy grades.
Sustainability4
Producing a kilogram of CW-6MC takes about 155 MJ of energy and emits 13 kg of CO₂ — less than 58% of nickel alloy grades. Typical recycled content is 40%.
Manufacturability7
CW-6MC's machinability is poor (22/100, better than 64% of nickel alloy grades); weldability excellent (85/100); 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 nickel alloy family
Yield strength against density for every nickel alloy grade FabDigit runs. CW-6MC is highlighted; hover a dot for its name, or open the interactive family chart.
Working with CW-6MC
Is CW-6MC easy to machine?
Tough, work-hardening alloy — rigid setup, sharp positive-rake carbide/ceramic tools, low speed with heavy feed, flood coolant, avoid dwelling.
Can CW-6MC be welded?
Very good weldability with GTAW/GMAW using ERNiCrMo-3 (AWS A5.14); low heat input, no preheat, PWHT normally unnecessary but re-solution treatment restores best corrosion resistance.
Can CW-6MC be formed, bent or molded?
Sand or investment cast with generous risering because of the wide freezing range; feed heavy sections and control Nb segregation, then solution treat and water quench.
CW-6MC 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 | 0.03 |
| Mn | ≤ 1 | 0.5 |
| Si | ≤ 1 | 0.6 |
| P | ≤ 0.02 | |
| S | ≤ 0.02 | |
| Cr | 20 – 23 | 21.5 |
| Mo | 8 – 10 | 9 |
| NbNb + Ta | 3.15 – 4.5 | 3.7 |
| Fe | ≤ 5 | 3 |
| Al | ≤ 0.4 | 0.2 |
| Ti | ≤ 0.4 | 0.2 |
| Ni | ≥ 58 (balance) |
What surface finishes work on CW-6MC?
Pickle/passivate (HNO₃-HF then nitric) to remove casting scale; takes electropolish and mechanical polish well, no anodizing applicable.
Surface treatments FabDigit runs on nickel alloy 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).
Plating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Nickel Alloy CW-6MC in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- N26625J26625N06625
- ASTM
- A494 CW6MC
How much does CW-6MC cost?
CW-6MC is a high-cost nickel alloy ($$$$), 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.
CW-6MC — frequently asked
What is CW-6MC used for?
CW-6MC is typically used for valve trim castings, pump casings for sour service and marine casting components. In short: weldable cast Alloy 625; all-round cast Ni-Cr-Mo; seawater and sour service.
What is the yield strength of CW-6MC?
CW-6MC has a typical yield strength of 315 MPa (45.7 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 70% of nickel alloy grades. Strength varies by condition: see the 4 listed tempers.
Is CW-6MC easy to machine?
Not especially — machinability is rated poor (22/100, better than 64% of nickel alloy grades). Tough, work-hardening alloy — rigid setup, sharp positive-rake carbide/ceramic tools, low speed with heavy feed, flood coolant, avoid dwelling.
Can CW-6MC be welded?
Yes — weldability is rated excellent (85/100). Very good weldability with GTAW/GMAW using ERNiCrMo-3 (AWS A5.14); low heat input, no preheat, PWHT normally unnecessary but re-solution treatment restores best corrosion resistance.
What surface finishes work on CW-6MC?
Pickle/passivate (HNO₃-HF then nitric) to remove casting scale; takes electropolish and mechanical polish well, no anodizing applicable.
Can CW-6MC be formed, bent or molded?
Sand or investment cast with generous risering because of the wide freezing range; feed heavy sections and control Nb segregation, then solution treat and water quench.
What is the maximum service temperature of CW-6MC?
CW-6MC is rated for continuous use to about 900°C (1,652 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CW-6MC-SA and CW-6MC-AC?
SA is the default condition — standard delivery condition for A494 CW-6MC castings: dissolves interdendritic carbides/Laves for maximum corrosion resistance and ductility. AC: only for non-critical or low-corrosivity duty — interdendritic Nb-rich Laves/carbides lower ductility and localized corrosion resistance. Yield strength is 315 MPa in SA versus 350 MPa in AC.
How much does CW-6MC cost?
CW-6MC is a high-cost nickel alloy ($$$$), 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 A494/A494M — Castings, Nickel and Nickel Alloy — ASTM International (2023)
- INCONEL alloy 625 technical bulletin — Special Metals Corporation (2013)
- ASM Handbook Vol. 1 & Vol. 2 — Properties of Nickel and Nickel Alloys / Castings — ASM International (1990)
- AWS A5.14 ERNiCrMo-3 filler metal specification — American Welding Society (2018)
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.