Inconel 718 is used for high-temperature and highly corrosive media. Such conditions are typical for power generation industry, chemical, petrochemical industry, aerospace engineering. Advanced nickel-based high strength alloys traditionally have nickel and chromium as their foundation, with elements such as molybdenum, tungsten and cobalt added to confer additional solid solution strengthening. Where high temperature strength is critical, additions of aluminum, titanium and niobium, resulting in precipitation hardening , must be added.
ASTM B983: Standard Specification for Precipitation Hardened or Cold Worked, Seamless Nickel Alloy Pipe and Tube
This standard covers high strength, seamless pipe/tube of nickel alloys (UNS N07022, UNS N07725, and UNS N07740). Pipe and tube shall be supplied in the cold worked or cold worked and precipitations hardened or solution annealed plus precipitation hardened and descaled conditions. When atmosphere control is used, descaling is not necessary. Each pipe or tube shall be tested by the manufacturer by either hydrostatic or a non-destructive electric test in accordance with Specification B829. This specification also describes chemical requirements, heat treatments, and mechanical properties, as well as calculation of mass or weight, sampling of chemical analysis, sampling for mechanical testing, specimen preparation, inspection, and certification. There shall be one test per lot for chemical analysis and one test per lot for tension test. If the specimen used in the mechanical test of any lot fails to meet the specified requirements, tow additional specimens shall be taken from different sample pieces and tested. The results of the tests on both of these specimens shall meet the specified requirements.
This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.
Alloy 718 Chemical composition
Alloy | % | Ni | Cr | Fe | Mo | Nb | Co | C | Mn | Si | S | Cu | Al | Ti |
718 | Min. | 50 | 17 | balance | 2.8 | 4.75 | 0.2 | 0.7 | ||||||
Max. | 55 | 21 | 3.3 | 5.5 | 1 | 0.08 | 0.35 | 0.35 | 0.01 | 0.3 | 0.8 | 1.15 |
Alloy 718 Physical Properties
Density / Specific Gravity | 8193 kg/m³ |
Melting point | 1321-1393 ℃ |
Alloy 718 Mechnical properties
Temp. °C/°F | Creep strain limit (10000h) (Rp1,0) N/mm2 | Creep rupture strength (10000h) (Rp1,0) N/mm2 | |||
Property | Density kg/dm3 | Temperature T °C/F | Specific heat J / kgK | Thermal conductivity W/mK | Electric resistance µΩ·cm |
817 (≥) | 314 (≥) | 32 | 13 | 34 | Solution and Aging, Annealing, Ausaging, Q+T,etc |
385 | 298 | 726 |