NiCr19NbMo is the EN symbol designation for a precipitation-hardenable nickel-chromium-iron superalloy, one of the most widely used superalloys in the world. This datasheet presents the material within the EN symbol designation system.
Originally an age-hardenable derivative of alloy 625, NiCr19NbMo derives its outstanding strength from the precipitation of gamma-prime (γ′, Ni₃(Al,Ti)) and gamma-double-prime (γ″, Ni₃Nb) phases during ageing, with niobium the key strengthening addition. It combines high tensile, fatigue, creep and stress-rupture strength up to about 700 °C with good oxidation resistance, excellent cryogenic toughness, and good weldability and forgeability. It is non-magnetic, is readily formed in both cold and hot conditions, and is used in the solution-treated and aged condition.
Typical applications include gas-turbine discs, blades and casings, aero- and rocket-engine components, oil-and-gas equipment for corrosive and sour environments, fasteners and cryogenic hardware.
| Property | Value | Unit |
|---|---|---|
| Density | 8.19 | g/cm³ |
| Melting range | 1260–1336 | °C |
| Elastic modulus | 200 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 13.0 | µm/m·°C |
| Thermal conductivity (20 °C) | 11.4 | W/m·K |
| Specific heat (20 °C) | 435 | J/kg·K |
| Structure | Austenitic (FCC) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel | Ni | 50.0 | 55.0 | Austenite former; γ′/γ″ matrix |
| Chromium | Cr | 17.0 | 21.0 | Oxidation / corrosion resistance |
| Iron | Fe | Balance | — | Base element (~18%) |
| Niobium | Nb (+Ta) | 4.75 | 5.50 | γ″ (Ni₃Nb) precipitation strengthening |
| Molybdenum | Mo | 2.80 | 3.30 | Solid-solution strengthening |
| Titanium | Ti | 0.65 | 1.15 | γ′ (Ni₃Ti) precipitation strengthening |
| Aluminium | Al | 0.20 | 0.80 | γ′ formation |
| Cobalt | Co | — | 1.00 | Residual |
| Carbon | C | — | 0.08 | Carbide formation |
| Manganese | Mn | — | 0.35 | Deoxidiser |
| Silicon | Si | — | 0.35 | Deoxidiser |
| Boron | B | — | 0.006 | Grain-boundary strengthening |
Solution-treated and aged condition, per EN reference data for W.Nr. 2.4668.
| Condition | Property | Value |
|---|---|---|
| Solution treated & aged | Tensile strength (Rm) | ≥1240 MPa |
| Solution treated & aged | 0.2% proof strength (Rp0.2) | ≥1035 MPa |
| Solution treated & aged | Elongation (A5) | ≥12 % |
| Solution treated & aged | Reduction of area (Z) | ≥15 % |
| Solution treated & aged | Hardness | ~36–44 HRC |
Values per EN reference data; properties depend on the solution and double-ageing treatment. Confirm against the inspection certificate (EN 10204).
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation | Very Good | To about 980 °C |
| Aqueous / general | Good | Chromium + molybdenum bearing |
| Sour gas (H₂S) | Good | Per heat-treatment condition |
| Chloride pitting / crevice | Good | Mo-bearing |
| Elevated-temperature strength | Excellent | Primary design advantage |
Corrosion and oxidation resistance is good for its class; the alloy is selected primarily for its exceptional combination of high strength, fatigue and creep resistance with adequate corrosion resistance.
A precipitation-hardenable superalloy; strengthened by solution treatment followed by double ageing.
Solution Treatment Solution anneal at approximately 950–1010 °C and cool (air or faster). A higher solution temperature (~1040–1065 °C) is used where creep-rupture performance is prioritised.
Precipitation Hardening (Ageing) Age in two steps — approximately 720 °C / 8 h, furnace cool to about 620 °C, hold ~8 h, air cool — precipitating γ′ (Ni₃(Al,Ti)) and γ″ (Ni₃Nb).
Good weldability, notably better than many γ′-strengthened superalloys owing to the sluggish γ″ ageing response. Welding is done in the solution-annealed condition with post-weld heat treatment.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching alloy 718 filler |
| GMAW / MIG | Good | Matching filler |
| EBW / laser | Good | Autogenous or matching filler |
Weld in the solution-annealed condition; apply post-weld solution and ageing to develop properties.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Solution-annealed for machining, then age |
| Machinability | Difficult; rigid setups, carbide tooling, slow speeds |
| Coolant | Ample coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | In the annealed condition; work-hardens rapidly |
| Hot forming | Readily forged; solution and age afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aero gas turbine | Discs, blades, casings, combustors | Strength + fatigue + creep to ~700 °C |
| Rocket / space | Engine components, hardware | Strength + cryogenic toughness |
| Oil & gas | Downhole and wellhead equipment | Strength + sour-service resistance |
| Industrial | Fasteners, springs, high-temperature parts | Strength + forgeability |
| Product Form | DIN / EN Standard | Notes |
|---|---|---|
| Bar, forgings and rings | W.Nr. 2.4668 · ISO 9723 | NiCr19Fe19Nb5Mo3 |
| Sheet, plate and strip | W.Nr. 2.4668 | — |
| Wire | W.Nr. 2.4668 · ISO 9724 | — |
| Inspection documents | EN 10204 | — |
Nickel-chromium-iron precipitation-hardenable superalloy. W.Nr. 2.4668 (NiCr19Fe19Nb5Mo3).
| EN Symbol | Ni % | Strengthening | Max Temp | Best Used For |
|---|---|---|---|---|
| NiCr19NbMo | 50–55 | γ′ + γ″ (Nb, Ti) | ~700 °C | Most-used superalloy; turbine discs, aero, oil & gas |
| NiCr20Nb (706) | 39–44 | γ′ + γ″ (Nb, Ti) | ~705 °C | 718-type strength, better fabricability (706) |
| NiCr21Mo9Nb (725) | 55–59 | γ′ + γ″ (Nb, Ti) | ~700 °C | Age-hardened 625; sour-service (725) |
| NiCr15Fe7TiAl (X-750) | ≥70 | γ′ (Al, Ti) | ~815 °C | Springs, bolts, fasteners (X-750) |
| NiCr22Mo9Nb (625) | ≥58 | Solid solution | ~980 °C | Corrosion + high-temperature strength (625) |




