Inconel 718 vs Waspaloy: Both age-hardenable superalloys — different temperature ranges
Inconel 718 vs Waspaloy
Side-by-side chemical composition and mechanical property comparison.
Overview
Inconel 718
2.4668
THE most widely used aerospace superalloy. Precipitation-hardened Ni-Cr-Fe alloy strengthened by gamma-prime and gamma-double-prime phases (Nb). Unique slow aging kinetics allow welding without cracking. UTS >1275 MPa aged. Used for gas turbine discs, jet engine components, rocket motors, cryogenic tanks, and oil/gas downhole tools. Service to 700°C.
Waspaloy
2.4654
Nickel-based gamma-prime strengthened superalloy — THE turbine disc material. Excellent creep-rupture strength up to 650°C (rotating) and 870°C (static). Developed 1950s by Pratt & Whitney. Triple-aged (solution + stabilize + precipitation) for peak properties. Superior to Inconel 718 above 650°C. Used for compressor and rotor discs, shafts, spacers, seals, rings, casings, and fasteners in gas turbine engines.
| Inconel 718 | Waspaloy | |
|---|---|---|
| Material Number | 2.4668 | 2.4654 |
| Category | Nickel Alloys | Nickel Alloys |
| Standard | ASTM B637 | ASTM B637 |
Chemical composition (wt%)
| Element | Inconel 718 | Waspaloy | Overlap |
|---|---|---|---|
| C | 0–0.08% | 0.02–0.1% | Partial |
| Si | 0–0.35% | 0–0.75% | OK |
| Mn | 0–0.35% | 0–1% | OK |
| Cr | 17–21% | 18–21% | OK |
Mechanical properties
| Property | Inconel 718 | Waspaloy | Unit |
|---|---|---|---|
| tensile_strength | ≥ 1275 | 1170–1310 | MPa |
| yield_strength | ≥ 1034 | 720–895 | MPa |
| elongation | ≥ 12 | 15–25 | % |
Compatibility Assessment
Inconel 718 is stronger at room temp (UTS 1240 vs 1170 MPa typ) and much easier to weld. Waspaloy has superior creep-rupture above 650°C and better thermal stability. Choose 718 up to 650°C (easier/cheaper); Waspaloy above 650°C for rotating parts.
Frequently Asked Questions
Is Inconel 718 the same as Waspaloy?
Inconel 718 and Waspaloy have a 55% composition overlap. Both age-hardenable superalloys — different temperature ranges
Can I replace Inconel 718 with Waspaloy?
Generally not recommended. The compositions differ significantly (55% overlap). These materials have different alloying concepts and are intended for different applications.
What is the difference between Inconel 718 and Waspaloy?
The main differences are in the following elements: C, Mo, Al, Ti. Inconel 718 is a Nickel Alloys grade, while Waspaloy is a Nickel Alloys grade.
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