Learn about Inconel® 718, a precipitation-hardenable Nickel-based alloy designed for high-performance a temperatures up to 1300°F (704°C).
Inconel® 718 Overview
Inconel® 718 is an austenitic nickel based super alloy designed primarily for strength in temperature extremes. Alloy 718 is also a precipitation hardening alloy, displaying exceptionally high yield, tensile and creep-rupture properties at temperatures well below freezing up to and beyond 1300°F (704°C). As a specialty alloy, 718 has improved mechanical short and long-term properties vs. other nickel alloys, and great fatigue strength in the age hardened conditions. Alloying material includes very specific mixtures of niobium, molybdenum, titanium, and aluminum to assist with performance
properties, as well as precipitation hardening.
Inconel® 718 Nominal Composition
| Si | Cr | Cb (Nb) | Ni | Mo | Ti | Fe | Co | Al | Cu | |
|---|---|---|---|---|---|---|---|---|---|---|
| Min | — | 17 | 4.75 | 50 | 2.80 | 0.65 | 0.20 | — | — | — |
| Max | 0.35 | 21 | 5.50 | 55 | 3.30 | 1.15 | Balance | 1.0 | 0.80 | 0.30 |
Physical Properties
| At 70°F | At 20°C | |
|---|---|---|
| Density | 0.296 lb/in³ | 8.19 g/cm³ |
| Modulus of Elasticity (E) | 29 x 10³ ksi | 200 GPa |
| Modulus of Rigidity (G) | 11.6 x 10³ ksi | 80 GPa |
| Coefficient of Expansion | 7.7 microinches/in.-°F (70-600°F) | 13.9 x μm/m°C (20-300°C) |
| Electrical Resistivity | 47.5 μ ohm.in | 121 μ ohm.cm |
| Thermal Conductivity | 79 Btu-in./ft.²hr.-°F | 11.4 W/m-K |
Typical Mechanical Properties - Spring Applications
| Condition | Heat Treatment | Tensile Strength | Suggested Operating Conditions |
|---|---|---|---|
| Annealed | 1800°F (980°C) | 115 – 145 ksi (790 – 1000 MPa) |
-330°F to 1200°F (-200°C to 650°C) |
| Spring Temper | 190 – 200 ksi (1517 – 1931 MPa) |
-330°F to 1200°F (-200°C to 650°C) |
|
| Spring Temper + Aged | After spring coiling Age: 1325°F (720°C) for 8 hours, furnace cool to 1150°F and hold for a total aging time of 18 hours. |
220 ksi minimum (1515 MPa) |
-330°F to 1200°F (-200°C to 650°C) |
Industry Standards
| Standard | Designation |
|---|---|
| EN | 2.4668 – NiCr19FeNb5Mo3 |
| ISO | NiCr19Nb5Mo3 |
| UNS | N07718 |
| AMS | 5662, 5663 |
| ASTM | B637 |
| AWS/SFA | 5.14 |
Available Specifications
| Wire & Bar | AMS 5662, AMS 5663, AMS 5664, AMS 5832, AMS 5962, ASME SB-637, ASTM B637, AWS A5.14 |
Applications
Alloy 718 a sought-after material for components used in aerospace, oil & gas recovery, and processing, as well as industrial and manufacturing applications that require heat for material processing. Common installations of Alloy 718 include:
- Engine and machinery components
- Gas turbine blades and other parts
- Aerospace fasteners
- High-temp filtration mesh
- Refinery equipment
- Cryogenic tanks, pumps, and valves
- Liquid rocket components
- Compressors and other high-pressure equipment
Alloy 718 can also be used for welding consumables, applied in high-strength aircraft components, and liquid rocket components involving cryogenic temperatures. Alloy 718 is selected for welding due to its superior resistance to post weld cracking.
Availability
Alloy 718 is a stocked product. Lead times vary based on processing required to finished form, but raw material is available at many Central Wire locations. Central Wire makes Alloy 718 available in the following forms:
- Drawn wire
- Rolled Strip
Packaging Options
- Coil
- Spools
- Bars
- Custom Packaging Available