Alloy 718 Seamless Nickel Alloy Pipe , Alloy Steel Tube UNS N07718 W.Nr. 2.4668
Alloy 718 UNS N07718 W.Nr. 2.4668 AMS 5589 AMS 5590 Seamless Nickel Alloy Pipe
Description:
Alloy 718 is a precipitation hardening nickel-chromium alloy that also contains additions of iron, niobium, molybdenum, aluminium and titanium, providing a unique combination of high strength and corrosion resistance together with excellent weldability.
The alloy possesses excellent tensile, fatigue, creep and rupture strengths across a wide temperature range from around -253ºC to 705ºC. The high chromium content present in the material results in excellent oxidation resistance up to temperatures of around 980ºC.
Alloy 718 also offers outstanding corrosion resistance in a variety of media. It excels in many environments including organic and inorganic acids (other than when strongly oxidising), hydrogen sulphide and sour gasses. It is also especially resistant to chloride stress-corrosion cracking. This combination of properties, coupled with its exceptional weldability results in a material that truly can be described as a "Superalloy".
Alloy 718 was initially developed for the aerospace industry but its excellent strength and corrosion resistance were recognised by the oil industry and it is now widely used in this field also.
Alloy 718 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.
Alloy 718 for the oil industry 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.
Related Specifications of Alloy 718
N07718
AMS 5662
AMS 5663
AMS 5664
ASTM B637
2.4668
NC19FeNb (FR)
NiCr19NbMo (DE)
Mechanical Properties
| Temper | Solution-treated | |
|---|---|---|
| Tensile Rm | 155 | ksi (min) |
| Tensile Rm | 1069 | MPa (min) |
| R.p. 0.2% Yield | 95 | ksi (min) |
| R.p. 0.2% Yield | 655 | MPa (min) |
| 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 | mm/m/°C |
| Modulus Elasticity | 200 | GPa |
| Electrical Resistivity | 1.32 | μohm/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 |
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