Hangbo Alloy Group
Shanghai · Est. 2012
UNS N07090 / W.Nr. 2.4632 — Chemical composition, mechanical properties, creep-rupture data, and high-temperature performance for gas turbine engineers and procurement professionals.
Nimonic 90 (UNS N07090 / W.Nr. 2.4632) is a precipitation-hardenable nickel-chromium-cobalt superalloy developed by Special Metals (formerly Wiggin Alloys) for high-temperature service in gas turbine engines. The alloy is strengthened by the addition of titanium and aluminum, which form the gamma-prime (Ni3(Ti,Al)) precipitate during aging treatment. The cobalt addition enhances solid-solution strengthening and raises the solvus temperature of the gamma-prime phase, enabling Nimonic 90 to operate at temperatures up to approximately 920°C (1688°F).
Compared to the earlier Nimonic 80A, Nimonic 90 offers significantly higher stress-rupture strength and creep resistance at elevated temperatures, making it the preferred choice for critically stressed rotating components in gas turbines. The alloy is supplied in the solution-annealed condition and aged to develop its full strength potential through a controlled two-step precipitation treatment.
The chemical composition of Nimonic 90 is designed to optimize the balance between precipitation hardening from the gamma-prime phase and solid-solution strengthening from chromium and cobalt. The titanium-to-aluminum ratio is carefully controlled to ensure the formation of the desired strengthening precipitates without promoting the formation of deleterious phases such as eta (Ni3Ti) platelets.
| Element | Min % | Max % |
|---|---|---|
| Nickel (Ni) | Balance | Balance |
| Chromium (Cr) | 18.0 | 21.0 |
| Cobalt (Co) | 15.0 | 21.0 |
| Titanium (Ti) | 1.80 | 3.00 |
| Aluminum (Al) | 0.80 | 2.00 |
| Iron (Fe) | — | 1.50 |
| Manganese (Mn) | — | 1.00 |
| Silicon (Si) | — | 1.00 |
| Carbon (C) | — | 0.13 |
| Copper (Cu) | — | 0.50 |
| Boron (B) | — | 0.020 |
| Zirconium (Zr) | — | 0.15 |
| Sulfur (S) | — | 0.015 |
Nimonic 90 has a face-centered cubic (FCC) austenitic matrix that remains stable across its entire service temperature range. The alloy's physical properties reflect the high nickel and cobalt content, which contribute to its relatively high density and moderate thermal conductivity. The low thermal expansion coefficient is advantageous for components that undergo thermal cycling, as it reduces thermal fatigue stresses.
| Property | Value | Unit |
|---|---|---|
| Density | 8.19 | g/cm3 |
| Melting Range | 1330–1360 | °C |
| Specific Heat (21°C) | 448 | J/kg·K |
| Thermal Conductivity (21°C) | 9.8 | W/m·K |
| Electrical Resistivity (21°C) | 1.30 | μΩ·m |
| Modulus of Elasticity (21°C) | 226 | GPa |
| Mean Coefficient of Thermal Expansion (21–100°C) | 12.7 | μm/m·°C |
| Mean Coefficient of Thermal Expansion (21–800°C) | 16.1 | μm/m·°C |
The following data represents typical properties for Nimonic 90 in the fully heat-treated condition (solution annealed + aged). The standard heat treatment consists of solution annealing at 1080°C for 8 hours followed by air cooling, then aging at 705°C for 16 hours followed by air cooling. This two-step treatment precipitates the gamma-prime strengthening phase in an optimal distribution.
| Property | Value |
|---|---|
| Tensile Strength | 1235 MPa (179 ksi) |
| Yield Strength (0.2% offset) | 810 MPa (117 ksi) |
| Elongation in 50 mm | 28% |
| Reduction of Area | 30% |
| Hardness (Rockwell C) | 35–42 HRC |
| Impact Strength (Charpy V-notch, room temp) | 40 J |
Nimonic 90 retains a substantial proportion of its room-temperature strength at elevated temperatures, which is the hallmark of a gamma-prime strengthened superalloy. The precipitate remains effective as a dislocation barrier up to approximately 80% of its solvus temperature, after which the strengthening contribution declines rapidly as the gamma-prime phase coarsens and eventually dissolves. The following data shows typical tensile properties at temperature for fully heat-treated material.
| Temperature (°C) | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| 21 (Room) | 1235 | 810 | 28 |
| 300 | 1100 | 750 | 25 |
| 500 | 1050 | 700 | 22 |
| 600 | 1020 | 680 | 20 |
| 700 | 880 | 620 | 18 |
| 800 | 650 | 480 | 22 |
| 900 | 350 | 230 | 35 |
One of the most critical properties for gas turbine applications is the stress-rupture strength. Nimonic 90 demonstrates excellent creep-rupture performance, which is why it has been specified for turbine blades and discs in both aero and industrial gas turbines for decades. Typical 100-hour rupture stresses at various temperatures are shown below.
| Temperature (°C) | 100-hr Rupture Stress (MPa) | 1000-hr Rupture Stress (MPa) |
|---|---|---|
| 600 | 710 | 610 |
| 700 | 455 | 350 |
| 750 | 340 | 245 |
| 800 | 230 | 150 |
| 850 | 145 | 85 |
| 900 | 80 | 40 |
Nimonic 90 has good oxidation resistance at elevated temperatures due to its 18–21% chromium content, which promotes the formation of a tenacious and protective chromium oxide (Cr2O3) scale. However, it is important to note that Nimonic 90 is primarily designed for high-temperature mechanical performance rather than aqueous corrosion resistance. Its corrosion behavior is summarized below.
Nimonic 90 is predominantly used in gas turbine engines where a combination of high creep strength, good fatigue resistance, and adequate oxidation resistance is required at temperatures between 600°C and 920°C. Key application areas include:
The standard heat treatment for Nimonic 90 is a two-stage precipitation-hardening process that produces an optimal distribution of gamma-prime precipitates. Proper heat treatment is essential to achieve the alloy's full mechanical potential:
Alternative heat treatments may be specified for specific applications. For instance, a double-aging treatment (705°C/16h + 650°C/8h) can provide improved notch-rupture strength in certain service conditions. All heat treatment parameters should be verified against the applicable material specification.
Hangbo Alloy Group supplies Nimonic 90 in the following product forms, conforming to AMS, BS, and customer-specific specifications:
| Standard | Description |
|---|---|
| AMS 5829 | Bar and Forging, Solution Heat Treated |
| AMS 5830 | Bar and Forging, Solution and Precipitation Heat Treated |
| BS HR 501 | Wrought Alloys for Turbine Blading (Nimonic 90) |
| BS HR 502 | Bars and Forgings for Turbine Discs |
| ASTM B637 | Hot-Worked and Cold-Worked Nickel Alloy Bar |
| EN 2.4632 | European Werkstoff Designation |
| ISO 6304 | Nickel-Based Superalloys — Definitions and Designations |
Hangbo Alloy Group maintains inventory of Nimonic 90 round bars and forgings in standard sizes. We can provide mill test certificates, third-party inspection reports (SGS, TUV), and custom heat treatment services. Our metallurgical team can assist with material selection and specification compliance for your gas turbine application.
For quotations, material certifications, or technical consultation, contact our sales team or call +86-136-1165-6360. We typically respond within 10 minutes.
Request a quotation for Nimonic 90 round bars, forgings, or wire. We stock standard sizes and accept custom orders with specific heat treatment requirements.