Q1: What is Inconel 718 (UNS N07718 / W-Nr 2.4668) and why is it used for aerospace compressor discs?
Answer:
Inconel 718 is a nickel-chromium alloy with niobium, molybdenum, and titanium.
Key properties:
Exceptional high-temperature strength (up to ~700°C / 1292°F).
Excellent creep, fatigue, and stress corrosion cracking resistance.
Good oxidation and corrosion resistance in harsh aerospace environments.
Application in high-pressure compressor discs: The material withstands extreme centrifugal forces, thermal cycling, and high stress, making it ideal for jet engines and gas turbines.
Q2: How does Inconel 718 compare with Inconel 600 and Incoloy 825?
Answer:
| Property | Inconel 718 | Inconel 600 | Incoloy 825 |
|---|---|---|---|
| Max Temp | ~700°C | ~1150°C | ~595°C |
| Strength | Very high (precipitation hardened) | Moderate | Moderate |
| Creep Resistance | Excellent | Low | Moderate |
| Corrosion Resistance | Good | Excellent in oxidizing environments | Excellent in acidic/chemical environments |
| Typical Use | Aerospace, high-pressure discs, turbine components | Heat exchangers, high-temp industrial equipment | Chemical, petrochemical, seawater applications |
✅ Summary: Inconel 718 is ideal for high-stress, high-temperature aerospace parts; Inconel 600 and Incoloy 825 are more for general corrosion or high-temperature industrial use.
Q3: What are the typical mechanical properties of Inconel 718 plates?
Answer:
Tensile Strength: 1,270–1,380 MPa (aged condition)
Yield Strength: 1,030–1,140 MPa
Elongation: 12–20%
Creep Resistance: Excellent at 600–700°C for long durations
Hardness: 34–40 HRC (depending on heat treatment)
These properties ensure durability under centrifugal stress and thermal cycling in aerospace applications.
Q4: What are the standards and specifications for Inconel 718 plates?
Answer:
ASTM B637 / B670: Nickel alloy plates for aerospace and high-temperature applications.
AMS 5662 / AMS 5383: Aerospace material specifications for high-strength nickel alloys.
W-Nr 2.4668 / UNS N07718: International designations for consistent chemical and mechanical properties.
Compliance ensures material traceability, quality, and safety in critical aerospace components.
Q5: How to select Inconel 718 for a high-pressure compressor disc application?
Answer:
Temperature & Creep Requirements: Confirm operating temperature ≤ 700°C; high creep resistance needed.
Mechanical Load: Verify tensile and yield strength meet centrifugal and thermal stress requirements.
Fatigue Resistance: High cycle fatigue is critical for rotating discs.
Corrosion Environment: Ensure resistance against oxidation and possible fuel/air contaminants.
Standards & Certification: Choose plates compliant with ASTM, AMS, or equivalent aerospace standards, with full material traceability and heat treatment certification.
