Direct answer: Solution-annealed Alloy 718 is the softer condition used for forming, machining or later heat treatment. Aged Alloy 718 has undergone precipitation hardening to develop substantially higher yield strength, tensile strength and hardness. Select the condition from the final component requirement and governing material specification.
Condition Comparison
| Property | Solution annealed | Solution treated and aged |
|---|---|---|
| Main purpose | Dissolve phases and prepare a workable structure | Develop final high strength |
| Formability | Better | Lower |
| Machining load | Generally lower, though work hardening remains important | Higher tool load and wear |
| Strength/hardness | Lower | Higher |
| Typical route | Form or rough machine, then age if required | Finish machine with allowance for final condition and distortion |
What Aging Does
Alloy 718 is strengthened mainly by fine gamma-double-prime and gamma-prime precipitates. A controlled age cycle forms these particles after solution treatment. One commonly referenced aerospace route holds near 718°C, furnace cools to about 621°C and continues the age before air cooling, but the exact cycle must follow the ordered AMS, ASTM or customer specification.
AMS 5662 vs AMS 5663
AMS 5662 is commonly associated with bars, forgings and rings supplied in a solution-treated condition for subsequent processing. AMS 5663 covers a precipitation-heat-treated high-strength condition. Do not convert one certification into the other merely by adding a shop heat treatment; all specification controls, testing and traceability must be satisfied.
When to Buy Each Condition
- Buy solution annealed when substantial forming or rough machining remains.
- Buy aged when the supplier must deliver final mechanical properties.
- For tight dimensions, plan the sequence around heat-treatment distortion.
- For welded parts, qualify the welding and post-weld heat-treatment route.
FAQ
Can solution-annealed 718 be used without aging?
It can be used only where its certified properties satisfy the design. Most high-strength Alloy 718 applications depend on aging.
Is annealed 718 easy to machine?
It is easier than aged 718 but remains a work-hardening, low-thermal-conductivity nickel alloy.
Does aging improve corrosion resistance?
Its main purpose is strength. Corrosion performance depends on environment, microstructure and fabrication condition.
Primary References
Engineering note: Values and acceptance criteria must be checked against the edition of the governing standard named in the purchase order. Application-specific design approval remains the responsibility of the purchaser or project engineer.
Post time: Sep-11-2026