Inconel X-750 vs Inconel 718: Both precipitation-hardened Ni superalloys — different strengthening mechanisms
Inconel X-750 vs Inconel 718
Side-by-side chemical composition and mechanical property comparison.
Overview
Inconel X-750
2.4669
Age-hardenable Ni-Cr-Fe superalloy for high-temperature spring and fastener applications. Strengthened by gamma-prime precipitation (Al+Ti). Oxidation and corrosion resistant to ~700°C service. Used for gas turbine springs, rocket engine thrust chambers, nuclear reactor components, and high-temp fasteners.
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.
| Inconel X-750 | Inconel 718 | |
|---|---|---|
| Material Number | 2.4669 | 2.4668 |
| Category | Nickel Alloys | Nickel Alloys |
| Standard | ASTM B637 | ASTM B637 |
Chemical composition (wt%)
| Element | Inconel X-750 | Inconel 718 | Overlap |
|---|---|---|---|
| C | 0–0.08% | 0–0.08% | OK |
| Si | 0–0.5% | 0–0.35% | OK |
| Mn | 0–1% | 0–0.35% | OK |
| S | 0–0.01% | — | — |
Mechanical properties
| Property | Inconel X-750 | Inconel 718 | Unit |
|---|---|---|---|
| tensile_strength | ≥ 1100 | ≥ 1275 | MPa |
| yield_strength | ≥ 690 | ≥ 1034 | MPa |
| elongation | ≥ 20 | ≥ 12 | % |
Compatibility Assessment
X-750 uses gamma-prime (Al+Ti) hardening for spring/fastener use to 700°C. 718 uses gamma-double-prime (Nb) for higher strength (1275 vs 1100 MPa) in disc/structural applications. X-750 has better long-term stability; 718 has higher peak strength.
Frequently Asked Questions
Is Inconel X-750 the same as Inconel 718?
Inconel X-750 and Inconel 718 have a 50% composition overlap. Both precipitation-hardened Ni superalloys — different strengthening mechanisms
Can I replace Inconel X-750 with Inconel 718?
Generally not recommended. The compositions differ significantly (50% overlap). These materials have different alloying concepts and are intended for different applications.
What is the difference between Inconel X-750 and Inconel 718?
The main differences are in the following elements: Cr, Ni, Al, Ti. Inconel X-750 is a Nickel Alloys grade, while Inconel 718 is a Nickel Alloys grade.
Related Comparisons
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