Inconel Alloy 718 • UNS N07718 • WNR 2.4668
Inconel 718 tubing is a nickel-chromium alloy which can be heat-treated to give high strength, good corrosion resistance, ease of formability and which can be welded with good resistance to strain age cracking. The alloy can be used at temperatures up to 700ºC.
For aerospace and power generation, Inconel 718 tubing is heat treated such that the hardness does not exceed 40HRC which is the maximum allowed by NACE MR-01-75/ ISO 15156: 3 to prevent stress corrosion cracking. The major applications in this field are Valves and precision tubing.
Alloy 718 for aerospace and power generation is heat treated to give maximum strength and high creep resistance with typical hardness values exceeding 42HRC. The major applications are components for gas turbines, aircraft engines, fasteners and other high strength applications.
Technical Data
Mechanical Properties
| Temper | Solution-treated | |
|---|---|---|
| Tensile Rm | 155 | ksi (Max) |
| Tensile Rm | 1069 | MPa (Max) |
| R.p. 0.2% Yield | 95 | ksi (Max) |
| R.p. 0.2% Yield | 655 | MPa (Max) |
| Elongation (2” or 4D gl) | 30 | % (min) |
Physical Properties (Room Temperature)
| Specific Heat (0-100°C) | 435 | J.kg-1.°K-1 |
| Thermal Conductivity | 11.4 | W.m -1.°K-1 |
| Thermal Expansion | 13 | μm/μm/°C |
| Modulus Elasticity | 200 | GPa |
| Electrical Resistivity | 1.32 | Ohm-cm |
| Density | 8.19 | g/cm3 |
Chemical Composition (% by weight)
| Element | Min | Max |
|---|---|---|
| C | – | 0.08 |
| Si | – | 0.35 |
| Mn | – | 0.35 |
| P | – | 0.015 |
| Al | 0.2 | 0.8 |
| B | – | 0.6 |
| Co | – | 1 |
| Cr | 17 | 21 |
| Cu | – | 0.3 |
| Fe | Balance | |
| Mo | 2.8 | 3.3 |
| Nb | 4.75 | 5.5 |
| Ni | 50 | 55 |
| Ti | 0.65 | 1.15 |