Inconel 625 vs Inconel 718: Both Ni superalloys — 718 is precipitation hardened, 625 is solid solution
Inconel 625 vs Inconel 718
Side-by-side chemical composition and mechanical property comparison.
Overview
Inconel 625
2.4856
Nickel-chromium-molybdenum-niobium superalloy. Solid-solution strengthened (no precipitation hardening required). Outstanding corrosion resistance from cryogenic to 982°C. Used for jet engine exhaust systems, marine components, chemical processing, flare stacks, and nuclear applications.
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 625 | Inconel 718 | |
|---|---|---|
| Material Number | 2.4856 | 2.4668 |
| Category | Nickel Alloys | Nickel Alloys |
| Standard | ASTM B443 | ASTM B637 |
Chemical composition (wt%)
| Element | Inconel 625 | Inconel 718 | Overlap |
|---|---|---|---|
| C | 0–0.1% | 0–0.08% | OK |
| Si | 0–0.5% | 0–0.35% | OK |
| Mn | 0–0.5% | 0–0.35% | OK |
| Cr | 20–23% | 17–21% | Partial |
Mechanical properties
| Property | Inconel 625 | Inconel 718 | Unit |
|---|---|---|---|
| tensile_strength | ≥ 827 | ≥ 1275 | MPa |
| yield_strength | ≥ 414 | ≥ 1034 | MPa |
| elongation | ≥ 30 | ≥ 12 | % |
Compatibility Assessment
Inconel 718 reaches 1275 MPa UTS (vs 827 MPa for 625) through Nb precipitation hardening. 625 has better corrosion resistance and weldability. 718 is THE aerospace disc alloy; 625 is for corrosion-critical structures.
Frequently Asked Questions
Is Inconel 625 the same as Inconel 718?
Inconel 625 and Inconel 718 have a 45% composition overlap. Both Ni superalloys — 718 is precipitation hardened, 625 is solid solution
Can I replace Inconel 625 with Inconel 718?
Generally not recommended. The compositions differ significantly (45% overlap). These materials have different alloying concepts and are intended for different applications.
What is the difference between Inconel 625 and Inconel 718?
The main differences are in the following elements: Cr, Mo, Ni, Al. Inconel 625 is a Nickel Alloys grade, while Inconel 718 is a Nickel Alloys grade.
Related Comparisons
View full data for each material:
Data provided for reference only. Always verify against the applicable specification for critical applications.
All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.