Nimonic 80A is a wrought, age-hardenable nickel–chromium alloy strengthened by additions of titanium, aluminium and carbon, developed for high-strength service at temperatures up to 815 °C (1500 °F). This datasheet presents the material within the trade-name designation system.
It is essentially alloy 75 made precipitation-hardenable: titanium and aluminium form a gamma-prime [Ni₃(Al,Ti)] phase during aging that gives high tensile and creep-rupture strength, while the 18–21% chromium content forms a protective Cr₂O₃ scale providing good oxidation and scaling resistance to about 1000 °C. It also resists sulphur compounds in combustion gases, making it suitable for exhaust valves in heavy-oil engines, and offers good resistance to nitric and other acids.
It is produced by high-frequency melting (for extruded forms), electroslag-refined material (for forgings) and vacuum-refined versions. Typical applications include gas-turbine components (blades, rings and discs), high-temperature bolts and fasteners, nuclear boiler tube supports, die-casting inserts and cores, and automobile exhaust valves. A prerequisite for welding is that the material be in the solution-treated condition; strength is developed by a subsequent age-hardening treatment.
Values per manufacturer data, solution-treated and aged condition.
| Property | Value | Unit |
|---|---|---|
| Density | 8.19 | g/cm³ |
| Melting range | 1320–1365 | °C |
| Young's modulus (20 °C) | 222 | GPa |
| Specific heat capacity (20 °C) | 448 | J/kg·K |
| Thermal conductivity (20 °C) | 11.2 | W/m·K |
| Electrical resistivity (20 °C) | 1.24 | µΩ·m |
| Coefficient of thermal expansion (20–100 °C) | 12.7 | µm/m·°C |
| Maximum oxidation-resistance temperature | ~1000 | °C |
| Useful strength to | ~815 | °C |
Limiting composition per ASTM B637 (UNS N07080).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Nickel | Ni | Balance | — | Austenitic FCC matrix; γ′-forming base |
| Chromium | Cr | 18.0 | 21.0 | Forms Cr₂O₃ scale; oxidation/corrosion resistance |
| Titanium | Ti | 1.8 | 2.7 | Primary γ′ [Ni₃(Al,Ti)] former; key strengthener |
| Aluminium | Al | 1.0 | 1.8 | γ′ former; strengthening |
| Iron | Fe | — | 3.0 | Residual |
| Cobalt | Co | — | 2.0 | Residual |
| Carbon | C | — | 0.10 | Carbide formation |
| Manganese | Mn | — | 1.0 | Deoxidiser |
| Silicon | Si | — | 1.0 | Deoxidiser |
| Boron | B | — | 0.008 | Grain-boundary strengthening |
| Zirconium | Zr | — | 0.15 | Grain-boundary strengthening |
| Copper | Cu | — | 0.2 | Residual |
| Sulphur | S | — | 0.015 | Residual impurity |
Typical room-temperature properties, solution-treated and aged condition.
| Property | Value | Source |
|---|---|---|
| Ultimate tensile strength | ≥1000 MPa (145 ksi) | Solution-treated + aged |
| 0.2% proof strength (yield) | ≥620 MPa (90 ksi) | Solution-treated + aged |
| Elongation at break | ≥20 % | Solution-treated + aged |
| Reduction of area | ≥12 % | Solution-treated + aged |
| Hardness | ≥300 HV | Solution-treated + aged |
Strength is developed by precipitation of γ′ during aging, giving far higher tensile and creep-rupture strength than the solution-strengthened alloy 75. Values are typical; confirm against the mill test certificate for each delivery.
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation / scaling | Good | Protective Cr₂O₃ scale to ~1000 °C |
| Creep / stress-rupture (to 815 °C) | Excellent | γ′ strengthening; primary selling point |
| Sulphur-bearing combustion gases | Good | Suitable for exhaust valves (heavy-oil engines) |
| Nitric / phosphoric acids | Good | Ni-Cr base |
| Chloride stress-corrosion cracking | Good | High nickel content |
| General corrosion | Good | Comparable to alloy 75 |
A precipitation-hardening alloy. Strength is developed by solution treatment followed by aging.
Solution Treatment Temperature: ~1080 °C (1975 °F), ~8 h, air cool
Aging Temperature: ~700 °C (1290 °F), ~16 h, air cool Purpose: precipitates γ′ [Ni₃(Al,Ti)] for high tensile and creep-rupture strength.
Anneal (softening): ~1040 °C (1904 °F), water quench or air cool. Welding must be carried out in the solution-treated condition, with age-hardening applied afterwards to develop full properties.
Weldable by MMA/SMAW, GTAW/TIG and GMAW/MIG using a matching filler metal. As a γ′-strengthening alloy it can be susceptible to strain-age cracking, so a prerequisite for welding is that the material be in the solution-treated condition; age-hardening is applied after welding.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG · GMAW / MIG | Good (solution-treated) | AWS A5.14 matching Ni-Cr-Ti filler (AWS 031) |
| SMAW / MMA | Good | Matching Ni-Cr electrode |
Post-weld solution treatment + aging is recommended to restore full strength; minimise restraint to avoid strain-age cracking.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Solution-treated (machine before final aging where possible) |
| Work hardening | High rate; rigid setup, positive rake, sharp tooling |
| Cutting | Low-to-moderate speed, ample feed, generous coolant |
Forming Processes
| Process | Notes |
|---|---|
| Hot forming | Above the solution range; ESR material for forgings |
| Cold forming | In solution-treated condition; high work-hardening rate |
| Final aging | After forming/machining to develop full strength |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Gas turbines | Blades, rings, discs | High creep-rupture strength to 815 °C |
| Aerospace | Fasteners, bolts, turbine hardware | High strength + oxidation resistance |
| Automotive | Exhaust valves (incl. heavy-oil engines) | Sulphur + high-temperature strength |
| Nuclear | Boiler tube supports | Creep strength + stability |
| Tooling | Die-casting inserts and cores | Hot strength + thermal fatigue |
| Marine / offshore | High-strength high-temperature hardware | Strength + corrosion resistance |
| Product Form | ASTM Standard | AMS Standard |
|---|---|---|
| Rod and bar | ASTM B637 | AMS 5662-type |
| Forgings | ASTM B637 | AMS 5662-type |
| Wire | ASTM B637-related | AWS 031 |
| Plate, sheet and strip | ASTM B637-related | — |
| Welding consumables | AWS A5.14 matching Ni-Cr-Ti filler (AWS 031) | — |
Age-hardenable heat-resistant Ni-Cr alloy. UNS N07080; ASTM B637 / ASME SB-637.
| Nimonic Grade | Ni % | Cr % | Other | Best Used For |
|---|---|---|---|---|
| Nimonic 80A | bal | 18–21 | Ti 1.8–2.7, Al 1.0–1.8 | Age-hardened Ni-Cr; high strength to 815°C |
| Nimonic 75 | bal | 18–21 | Ti 0.2–0.6 | Solution-strengthened (base); oxidation to 1100°C |
| Incoloy A-286 | 24–27 | 13.5–16 | Ti+Al (Fe-base γ′) | Iron-base age-hardened; to 704°C |
| Waspaloy | bal | 18–21 | Co 12–15, Mo, Ti+Al | Higher-strength γ′; sustained >700°C |
| Inconel 718 | 50–55 | 17–21 | Nb+Ti+Al | Highest strength; turbine discs to 650°C |




