Alloy 718
Inconel 718 is an austenitic nickel-base superalloy which is used in applications requiring high strength to approximately 1400°F (760°C) and oxidation resistance to approximately 1800°F (982°C). In addition, the alloy exhibits excellent tensile and impact strength even at cryogenic temperatures. Inconel 718 is widely used for static and rotating components in stationary gas turbines, rocket drives and spacecraft, motor vehicle turbo chargers, high-strength screws, springs and mounting elements, and for heat-resistant tools in forgeries, extruders and separating shearers.
Quken offers Inconel 718 in following forms:
| Product form | Standard | Size available mm |
|---|---|---|
| Strip | AMSE 5596 | 0.05~2.0*3~540*C |
| Sheet | ASME SB670 | 1.5~6*1000~1500*2000~6000 |
| Plate | ASME SB670 | 8~25*1000~1500*2000~6000 |
| Bar | ASME SB637 | φ3.5~200*100~6000 |
| Wire | ASME SB637 | φ1~3*C |
Designations and standards:
| Standard | Material designation |
|---|---|
| EN | 2.4668 - NiCr19Fe19Nb5Mo3 |
| ISO | NiCr19Nb5Mo3 |
| UNS | N07718 |
| AFNOR | NC19FeNb |
Chemical composition %:
| Ni | Cr | Fe | Mo | Nb | Al | Ti | |
|---|---|---|---|---|---|---|---|
| MIN. | 50.0 | 17.0 | Bal. | 2.0 | 4.75 | 0.2 | 0.65 |
| MAX. | 55.0 | 21.0 | Bal. | 13.3 | 5.5 | 0.8 | 1.15 |
| Mn | S | Si | C | Co | Cu | ||
| MAX. | 0.35 | 0.015 | 0.35 | 0.08 | 1.0 | 0.3 |
Physical Constants:
| Density (Annealed Condition) | 0.296 lb/in3, 8.19g/cm3 |
| Melting Range (Approx.) | 2300-2444 °F / 1260-1340 °C |
| Electrical Resistivity | 118 Microhm·cm |
| Thermal Expansion Coefficient (25°C to 100°C) | 11.8 x 10-6/°C |
| Thermal Conductivity (100°C) | 14.7W/m·K |
Mechanical Properties:
| Yield Strength 0.2% Offset | Tensile Strength | Elongation In 2inches | Hardness | ||
|---|---|---|---|---|---|
| KSI | MPa | KSI | MPa | % | HB |
| 105 Max | 725 Max | 150 Max | 1035 Max | 30 Min | 363 Max |
Weldability
Satisfactory welds can be produced in both the solution treated and fully-aged conditions using inert gas-shielded arc ,plasma arc, electron beam, and resistance welding techniques. Because of the sluggish aging response, ATI 718-HS &DA alloys can be welded without hardening during the heating and cooling cycles, and the aged alloy can be repairwelded several times without cracking even in complex weldments.
Heat Treatment
For high strength processed material (718-HS)Solution treat at 1,725 - 1,875° F (941 - 1,024° C) for 1-2 hours. Rapid cool. Age at 1,325° F (718° C) for 8 hours. Furnace cool to 1,150 F (621° C).
For direct age processed material (718-DA)Age at 1,325° F (718° C) for 8 hours. Furnace cool to 1,150° F (621° C). Hold 8 hours. Air cool. Rapid cool after final hot working operations.
No solution treating is required.
Applications
- Springs, fasteners
- Tooling
- Liquid fuel rocket motor components
- Gas turbine engine parts
- Cryogenic tanks
- Pumps and valves