Alloy 718
UNS N07718
Description
Alloy 718, often referred to as Inconel 718, is a precipitation-hardenable nickel-chromium alloy. It has high creep-rupture strength at high temperatures to about 700 °C (1290 °F), oxidation resistance to approximately 1800 °F (982 °C) and excellent tensile and impact strength even at cryogenic temperatures. In addition, this alloy has excellent weldability when compared to the nickel-base superalloys hardened by aluminum and titanium, and the relatively slow response to precipitation hardening permits repair welding of the alloy even in the aged condition. Alloy 718 has been used for jet engine and high-speed airframe parts.
Chemical Component
| Ni + Co | Cr | Ti | Mo | Cb+Ta | Fe | Al | Co | C | Cu | Mn | Si | S | P | B |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 50.0-55.0% | 17.0-21.0% | 0.65-1.15% | 2.8-3.3% | 4.75-5.5% | balance | 0.2-0.8% | 1.0% max | 0.08% max | 0.3% max | 0.35% max | 0.35% max | 0.015% max | 0.015% max | 0.006% max |
Basic Information
| Items | Alloy 718 |
|---|---|
| Catalog | ACMA-Ni-A013 |
| Density | 0.296 lb/in3 annealed, 0.274 lb/in3 aged |
| Coefficient of Thermal Expansion, in/in°F x 10-6 | 70-200 °F: 7.3; 70-400 °F: 7.5; 70-600 °F: 7.7; 70-1000 °F: 8.1; 70-1200 °F: 8.4; 70-1400 °F: 8.9 |
| Thermal Conductivity, Btu· ft/ft2·hr· °F | 70 °F: 6.4; 200 °F: 7.2; 400 °F: 8.2; 600 °F: 9.3; 1000 °F: 11.3; 1200 °F: 12.3; 1400 °F: 13.3 |
| Modulus of Elasticity Dynamic, psi x 106 | 70 °F: 29; 200 °F: 28; 400 °F: 27; 600 °F: 26; 1000 °F: 25; 1200 °F: 24; 1400 °F: 22 |
| Melting Range | 2410-2540 °F |
Material Forms
Alfa Chemistry offers Alloy 718 in a variety of forms, including
- Plate
- Round Bar
- Sheet
Mechanical Properties
- Typical room temperature properties, 1800 °F annealed condition
| Ultimate Tensile Strength, ksi | 0.2% Yield Strength, ksi | Elongation, % | Hardness, Rockwell B |
|---|---|---|---|
| 135 | 70 | 45 | 100 |
- Average tensile properties, ½" bar annealed 1800 °F, aged 1325/1150 °F
| Temperature, °F | 70 | 400 | 800 | 1000 | 1200 | 1400 |
| Ultimate Tensile Strength, ksi | 210 | 198 | 191 | 185 | 168 | 111 |
| 0.2% Yield Strength, ksi | 175 | 163 | 156 | 155 | 149 | 110 |
| Elongation, % | 22 | 20 | 19 | 18 | 19 | 27 |
| Hardness, Rockwell C | 42-44 | - | - | 40-41 | 40-41 | 33-34 |
- Typical stress rupture, bar, annealed 1800 °F, aged 1325/1150 °F
| Temperature, °F | 1100 | 1200 | 1300 | 1400 |
| 100 Hours, ksi | 170 | 110 | 75 | 44 |
| 1,000 Hours, ksi | 130 | 85 | 55 | 25 |
Specifications
Applications
Alloy 718 can be used in a variety of applications, including:
- Gas turbine engine parts
- Liquid fuel rocket motor components
- Springs, fasteners
- Cryogenic tanks
- Pumps and valves
- Tooling
- Spacers
- Rocket Motors
- Space Craft
- Nuclear Reactors
- Oil & Gas Equipment
* Technical data included herein should be used as a guideline only, and should not be construed as maximum or minimum values for specification or for final design, or for a particular use or application. The data may be revised anytime without notice.
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