Nimonic 80A and Waspaloy are nickel-based, gamma prime hardening superalloys. Both harden with titanium and aluminium and both carry load at high temperature. Waspaloy is a step above Nimonic 80A.
When cobalt and molybdenum are added
According to our datasheets, Nimonic 80A is a simple nickel–chromium–titanium–aluminium alloy: nickel 76% (balance), chromium 19.0–21.0%, titanium 1.8–2.7%, aluminium 1.0–1.8%. There is no cobalt or molybdenum.
In Waspaloy, 12–15% cobalt and 3.5–5.0% molybdenum are added to the same backbone. Titanium is also raised to 2.75–3.50%. Cobalt delays the softening of the matrix at high temperature; molybdenum provides solid solution hardening; more titanium means more gamma prime precipitate.
The result is clear in the figures: the tensile strength of Nimonic 80A is 1000–1200 MPa and its yield strength 700–850 MPa; its service range is -200 °C … 850 °C. In Waspaloy the tensile strength is 1200–1500 MPa, the yield ~1000 MPa, and creep stability is superior in the 750–870 °C range.
The advantage of Nimonic 80A is simplicity and cost: containing no cobalt it is markedly more economical and easier to machine.
Comparison in numbers
| PROPERTY | Nimonic 80A | Waspaloy |
|---|---|---|
| Nickel (Ni) | 76% (balance) | 58 – 61% |
| Chromium (Cr) | 19.0 – 21.0% | 18 – 21% |
| Cobalt (Co) | — | 12 – 15% |
| Molybdenum (Mo) | — | 3.5 – 5.0% |
| Titanium (Ti) | 1.8 – 2.7% | 2.75 – 3.50% |
| Aluminium (Al) | 1.0 – 1.8% | 1.20 – 1.60% |
| Iron (Fe) | max 3.0% | max 2.0% |
| Carbon (C) | max 0.10% | 0.02 – 0.10% |
| Tensile strength Rm | 1000 – 1200 MPa | 1200 – 1500 MPa |
| Yield strength Rp0.2 | 700 – 850 MPa | ~1000 MPa |
| Elongation | 15 – 20% | — |
| Hardness | — | 35 – 45 HRC |
| Density | 8.19 g/cm³ | 8.19 g/cm³ |
| Melting range | 1320 – 1380 °C | 1320 – 1380 °C |
| Service temperature | -200 °C … 850 °C | superior creep stability in the 750 – 870 °C range |
| UNS | N07080 | N07001 |
| AMS | 4378 · 5829 | 5544 · 5706 |
Values are taken from our product datasheets; section thickness and the applied heat treatment regime change the result.
Which one, and when?
Nimonic 80A is sufficient — internal combustion engine exhaust valves, turbine blades and fasteners, gas turbine combustion chamber parts, heat treatment fixtures, high-temperature bolts. Its most common use is in the exhaust valves of large diesel and gas engines.
Waspaloy is required — turbine discs and shaft connections, highly stressed hot section parts, components carrying load above 850 °C. If the specification calls out AMS 5544 or AMS 5706, it cannot be substituted.
Neighbouring alloys
For high strength at lower temperature, see our Inconel 718 – Waspaloy comparison; for a cobalt-based alternative, Haynes 25.
Technical datasheets
Nimonic 80A — chemical composition, mechanical values, standard equivalents
Waspaloy — chemical composition, mechanical values, standard equivalents
Both grades are supplied to order in round bar, flat bar, plate, sheet, pipe and forged forms. Contact us for a quotation.