AMS 5662 vs AMS 5663 – Inconel 718 Explained
A high-precision metallurgical comparison of AMS 5662 and AMS 5663 specifications for Inconel 718, covering heat treatment condition, mechanical properties, microstructure, and industrial applications in aerospace and gas turbine manufacturing.
Introduction to Inconel 718 Specifications
Inconel 718 is a precipitation-hardened nickel-based superalloy widely used in aerospace, gas turbines, nuclear reactors, and high-temperature structural systems. AMS 5662 and AMS 5663 define two critical product conditions for wrought forms such as bars, forgings, and rings.
Caution: Confusing AMS 5662 with AMS 5663 can lead to incorrect heat treatment selection, extreme machining difficulties, or catastrophic component failure in service.
What are AMS 5662 and AMS 5663?
| Specification | Description |
|---|---|
| AMS 5662 | Inconel 718 supplied in the solution heat treated and precipitation hardened (aged) condition. This material has had its full mechanical strength developed prior to delivery. |
| AMS 5663 | Inconel 718 supplied in the solution annealed condition only. It is intended for further fabrication, severe machining, or forming, and requires subsequent aging to reach full strength. |
Rule of Thumb:
AMS 5662 = Final aged strength condition (Hard).
AMS 5663 = Soft, machinable intermediate condition (Soft).
AMS 5662 = Final aged strength condition (Hard).
AMS 5663 = Soft, machinable intermediate condition (Soft).
Heat Treatment Condition Differences
| Process Step | AMS 5662 (Aged) | AMS 5663 (Annealed) |
|---|---|---|
| Solution Annealing | Completed (≈980°C) | Completed (≈980°C) |
| Aging Treatment | Fully aged (720°C / 620°C cycles) | Not applied |
| Strength Level | High strength (final condition) | Low–medium strength |
| Machinability | Poor / Difficult | Excellent / Standard for Superalloys |
| Typical Use Stage | Final component machining | Intermediate manufacturing & forming |
Mechanical Property Comparison
The structural difference between the two specifications translates heavily into their mechanical properties.
| Property | AMS 5662 (Typical) | AMS 5663 (Typical) |
|---|---|---|
| Tensile Strength | High (≈1240–1400 MPa) | Moderate (≈900–1100 MPa) |
| Yield Strength | High (≈1000+ MPa) | Lower (≈600–800 MPa) |
| Hardness | HRC 36–44 | HRC 20–30 |
| Ductility / Elongation | Moderate (≈12-15%) | High (≈30%+) |
Key Engineering Differences
AMS 5662
- Final heat-treated condition.
- High-strength precipitation hardened structure (γ” and γ’ phases fully formed).
- Used in flight-ready aerospace components.
- Tooling costs for machining are high due to material hardness.
AMS 5663
- Solution annealed condition only.
- Soft microstructure optimized for heavy machining or forming.
- Requires a final precipitation aging cycle after fabrication by the manufacturer.
- Preferred for complex, near-net-shape machining operations.
“Buying AMS 5663 saves massive amounts of time and money on tool wear during CNC operations, provided the facility has the capability to perform the final aging heat treatment in-house.”
Industrial Applications
- AMS 5662: Fasteners, simple turbine disks, jet engine shafts, structural aerospace hardware where minimal final machining is required.
- AMS 5663: Forging blanks, complex machined parts, prototypes, deep-drawn components that require heavy plastic deformation before final hardening.
Strength Comparison Visualization
Visual breakdown of how the heat treatment condition impacts the core mechanical properties.
Frequently Asked Questions
No. AMS 5663 is in the solution-annealed condition. It lacks the yield strength and high-temperature creep resistance required for active service. It must undergo the final aging heat treatment cycle (transitioning its properties to match AMS 5662) before it can be put into service.
Significantly. AMS 5662 has a hardness between 36-44 HRC due to precipitation hardening, causing rapid tool wear, work hardening, and slower feed rates. AMS 5663 (20-30 HRC) is much softer and is specifically requested to facilitate easier machining.
Metallurgically, yes. Once AMS 5663 is subjected to the standard double-aging cycle (typically 720°C for 8 hours, furnace cool to 620°C, hold for 8 hours), its mechanical properties will satisfy the requirements of AMS 5662.
AMS 5663 is far superior for welding. Welding Inconel 718 in the aged condition (AMS 5662) makes it highly susceptible to strain-age cracking in the Heat Affected Zone (HAZ). It is standard practice to weld in the annealed condition (AMS 5663) and age the entire assembly afterward.