NiCr23Co12Mo is a solid-solution-strengthened nickel–chromium–cobalt–molybdenum alloy with an exceptional combination of high-temperature strength and oxidation resistance. The high nickel and chromium contents make it resistant to a variety of both reducing and oxidising media; aluminium (with chromium) provides oxidation resistance at high temperature; and cobalt with molybdenum imparts solid-solution strengthening. This datasheet presents the material within the European (DIN / EN / Werkstoff-Nummer / VdTÜV) standard system.
The combination of high strength and oxidation resistance at temperatures over 980 °C (1800 °F) makes the alloy an attractive material for gas-turbine components such as ducting, combustion cans, and transition liners, in both aircraft and land-based engines. It is also used for catalyst-grid supports in nitric acid production, heat-treating baskets, reduction boats in molybdenum refining, and components of fossil-fuelled and nuclear power-generating plant.
The alloy is supplied solution-annealed, which provides a coarse grain structure for the best creep-rupture strength and good room-temperature bend ductility. It is not an age-hardening alloy in normal use; strength derives from solid-solution effects and, after long exposure at 650–760 °C, from carbide and gamma-prime precipitation. It resists high-temperature carburisation and nitriding, and retains ductility after prolonged high-temperature exposure.
Typical values at room temperature, solution-annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 8.36 | g/cm³ |
| Melting range | 1332–1380 | °C |
| Elastic modulus (25 °C) | 211 | GPa |
| Shear modulus (25 °C) | 81 | GPa |
| Poisson's ratio | 0.30 | — |
| Specific heat capacity (26 °C) | 419 | J/kg·K |
| Electrical resistivity (20 °C) | 1.22 | µΩ·m |
| Coefficient of thermal expansion (20–100 °C) | 11.6 | µm/m·°C |
| Maximum service temperature | ~1100 | °C |
| Crystal structure | Face-centred cubic (FCC) | — |
Composition per EN 10302 (W.Nr. 2.4663, NiCr23Co12Mo / ISO NiCr22Co12Mo9).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel | Ni | Balance | — | Austenitic FCC matrix |
| Chromium | Cr | 20.0 | 23.0 | Oxidation / corrosion resistance |
| Cobalt | Co | 11.0 | 14.0 | Solid-solution strengthening |
| Molybdenum | Mo | 8.5 | 10.0 | Solid-solution strengthening |
| Aluminium | Al | 0.7 | 1.4 | Oxidation resistance |
| Iron | Fe | — | 2.0 | Residual |
| Carbon | C | 0.05 | 0.10 | Carbide strengthening |
| Titanium | Ti | 0.2 | 0.6 | Carbide former |
| Silicon | Si | — | 0.2 | Deoxidiser |
| Manganese | Mn | — | 0.2 | Deoxidiser |
| Copper | Cu | — | 0.5 | Residual |
| Boron | B | — | 0.006 | Trace |
| Phosphorus | P | — | 0.01 | Residual impurity |
| Sulphur | S | — | 0.01 | Residual impurity |
Nominal: Ni-22Cr-12Co-9Mo-Al. Cobalt and molybdenum give solid-solution strengthening for high-temperature strength to ~1100 °C; aluminium with chromium provides oxidation resistance.
Solution-annealed (+AT) condition, per EN 10302 for W.Nr. 2.4663.
| Property | Value | Unit |
|---|---|---|
| Tensile strength (Rm) | ≥700 | MPa |
| 0.2% proof strength (Rp0.2) | ≥270 | MPa |
| Elongation at fracture (A) | ≥35 | % |
Values per EN 10302 (creep-resisting alloys). Confirm against the inspection certificate (EN 10204).
Modulus of elasticity decreases with temperature (solution-annealed):
| Temperature | Tensile modulus | Shear modulus |
|---|---|---|
| 25 °C | 211 GPa | 81 GPa |
| 200 °C | 201 GPa | 77 GPa |
| 400 °C | 188 GPa | 72 GPa |
| 600 °C | 173 GPa | 66 GPa |
| 800 °C | 157 GPa | 61 GPa |
| 1000 °C | 139 GPa | 53 GPa |
The alloy displays exceptionally high creep-rupture strength even at 980 °C (1800 °F) and above — the primary reason for its selection in long-term, high-stress, high-temperature service. Creep strength derives from the solid-solution Co/Mo matrix plus carbide precipitation.
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation (air) | Outstanding | Cr + Al form protective oxide; service over 980 °C |
| Cyclic oxidation | Outstanding | Retains protective oxide under severe thermal cycling to 1095 °C |
| Carburisation | Excellent | Lowest weight gain among comparable alloys in gas-carburising tests |
| Nitriding | Good | Good resistance; can form internal Al nitrides in highly oxidising combustion atmospheres |
| Reducing media | Very Good | High Ni + Mo content |
| Aqueous corrosion | Good | Ni-Cr-Mo gives resistance to many wet environments; normally used hot |
| Metallurgical stability | Excellent | Retains ductility after prolonged high-temperature exposure |
Normally used in the solution-annealed condition for best creep-rupture strength and bend ductility. Not an age-hardening alloy in normal service.
Solution Anneal Temperature: 1175 °C (2150 °F), time commensurate with section size Cooling: Water quench or rapid air cool Purpose: Coarse grain structure for maximum creep-rupture strength.
Re-solution Anneal (after cold work / forming) Temperature: 1121 °C (2050 °F), air cool Purpose: Recrystallises cold-worked structure while limiting grain growth; preserves low-cycle-fatigue performance.
Annealing for cold forming: 1040 °C (1900 °F).
Excellent weldability. Filler metal of matching composition is used; deposited weld metal is comparable to the wrought alloy in strength and corrosion resistance.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Excellent | DIN EN ISO 18274 S Ni 6617 (NiCr23Co12Mo) |
| GMAW / MIG | Excellent | DIN EN ISO 18274 S Ni 6617 (NiCr23Co12Mo) |
| SMAW / stick | Good | DIN EN ISO 14172 E Ni 6617 |
After cold forming and welding, a re-solution anneal at 1121 °C (2050 °F) is recommended to restore properties. Owing to its strength and work-hardening rate, joining techniques follow standard nickel-alloy practice.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Tooling | Sharp tools, positive rake angles to minimise work hardening |
| Cutting parameters | Sufficient feed and depth of cut to avoid burnishing |
| Work hardening | High rate; rigid setup, keep tool engaged |
| Preferred condition | Solution-annealed |
Forming Processes
| Process | Notes |
|---|---|
| Hot forming / forging | 1010–1205 °C; light working down to 925 °C; high forces due to elevated-temperature strength |
| Cold forming | Readily cold-formed; high work-hardening rate; cold-form in fine-grain condition with frequent intermediate anneals |
| Annealing for cold forming | 1040 °C |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aerospace gas turbines | Ducting, combustion cans, transition liners | High-temperature strength + oxidation resistance over 980 °C |
| Land-based gas turbines | Hot gas path structures, combustion components | Creep + low-cycle-fatigue strength |
| Chemical / petrochemical | Catalyst-grid supports (nitric acid), reformer tubes | Carburisation and oxidation resistance |
| Thermal processing | Heat-treating baskets, reduction boats (Mo refining) | High-temperature corrosion resistance |
| Power generation | Fossil-fuelled and nuclear plant components, ultrasupercritical boiler tubes | Creep-rupture strength + metallurgical stability |
| Product Form | DIN Standard | VdTÜV | ISO |
|---|---|---|---|
| Rod and bar | DIN 17752 | VdTÜV 485 | — |
| Wire | DIN 17753 | — | ISO 9724 |
| Forgings | DIN 17754 | — | — |
| Plate, sheet and strip | DIN 17750 | VdTÜV 485 | ISO 6208 |
| Pipe and tube | DIN 17751 | VdTÜV 485 | ISO 6207 |
| Composition | DIN 17744 | — | — |
VdTÜV material data sheet 485 covers sheet, plate, bar and tubing for pressure-vessel service.
| EN Symbol | Ni % | Cr % | Mo % | UTS (annealed) | Max Temp. | Best Used For |
|---|---|---|---|---|---|---|
| NiCr23Co12Mo | 44.5 | 20–24 | 8–10 | ~734 MPa | ~1100 °C | Gas-turbine combustion; ducting; max creep+oxidation |
| NiCr22Mo9Nb | ≥58 | 20–23 | 8–10 | ~830 MPa | ~980 °C | Universal corrosion resistance; seawater |
| NiCr23Fe | 58–63 | 21–25 | — | ~550 MPa | ~1250 °C(ox) | Cyclic oxidation; radiant tubes |
| NiCr15Fe | ≥72 | 14–17 | — | ~655 MPa | ~1095 °C | General high-temp; carburisation/nitriding |
| NiCr25FeAlY | bal | 24–26 | — | ≥675 MPa | ~1200 °C | Extreme oxidation + creep; furnace rolls |




