Designation
- Grade
- Alloy 718
- UNS
- N07718
- Standard
- SAE AMS 5383 (investment castings)
- Family
- Nickel-based alloys
- Density
- ≈ 8.19 g/cm³
- Usual delivery condition
- Solution treated and precipitation hardened
Chemical composition
| Element | Mass fraction, % |
|---|---|
| Ni | 50.0–55.0 |
| Cr | 17.0–21.0 |
| Nb+Ta | 4.75–5.50 |
| Mo | 2.80–3.30 |
| Ti | 0.65–1.15 |
| Al | 0.20–0.80 |
| Fe | bal. |
Main elements only. Phosphorus, sulphur and residual-element limits are specified in the standard and are not reproduced here.
Mechanical properties
Mechanical properties depend on the heat-treatment condition and the ordering specification and are therefore not listed as single values. They are agreed per project.
Characteristics
- Corrosion and oxidation behaviour
- Designed for oxidation resistance and strength at high temperature
- Weldability
- Possible with qualified procedure; preheat and/or post-weld heat treatment as specified
- Machinability
- Difficult; rigid set-ups, low cutting speeds or grinding
- Typical applications
- Aerospace Turbine components Energy High-temperature service
International cross-reference
| System | Designation | Relationship |
|---|---|---|
| W.-Nr. | 2.4668 | Similar composition |
| UNS (wrought) | N07718 | Comparable properties |
Casting and processing considerations
Melting practice has a strong influence on quality: reactive elements such as aluminium and titanium in superalloys normally require vacuum melting and pouring, while corrosion-resistant grades are commonly air melted with careful control of carbon and silicon. Corrosion-resistant grades are solution annealed; weld repair and its heat treatment must follow the material specification.
Reference data compiled from the cited standards for orientation. Always work from the current edition of the governing specification; values are not a guaranteed LOSTWAX delivery specification.