Nickel-Chromium alloy being precipitation hardenable and having high creep-rupture strength at high temperatures to about 700°C (1290°F). It has higher strength than Inconel® X-750 and better mechanical properties at lower temperatures than Nimonic 90 and Inconel® X-750. Inconel® 718 has exceptional weldability compared to the Nickel-base super alloys hardened by Aluminium and Titanium.
"Inconel®" is registered trademarks of the Special Metals Corporation group of companies.
The chemical composition of Inconel® 718 is indicated in the table below:
Element | Min % | Max % |
C | – | 0.08 |
Mn |
– |
0.35 |
Si |
– |
0.35 |
P |
– |
0.015 |
S |
– |
0.015 |
Cr |
17.00 |
21.00 |
Ni |
50.00 |
55.00 |
Mo |
2.80 |
3.30 |
Nb/Cb |
4.75 |
5.50 |
Ti |
0.65 |
1.15 |
Al |
0.20 |
0.80 |
Co |
– |
1.00 |
Ta |
– |
0.05 |
B |
– |
0.006 |
Cu |
– |
0.30 |
Pb |
– |
0.0005 |
Bi |
– |
0.00003 |
Se |
– |
0.0003 |
Fe |
bal |
|
Inconel® 718 density, melting point, coefficient of expansion, modulus of rigidity, and elasticity is indicated in the table below:
Density |
Melting Point |
Coefficient of Expansion |
Modulus of Rigidity |
Modulus of Elasticity |
8.19g/cm³ |
133 6 °C |
13.0 μm/m °C (20 – 100 °C) |
77.2 kN/mm² |
204.9 kN/mm² |
0.296 lb/in³ |
2437 °F |
7.2 x 10-6 in/in °F (70 – 212 °F) |
11197 ksi |
29719 ksi |
The typical heat treatment of Inconel® 718:
Condition as supplied by AWI | Type | Temperature | Time | Cooling |
No. 1 or Spring Temper | Anneal | 980 °C (1800 °F) | 1hr | Air |
Age Harden | 720 °C (1330 °F) | 8hr | Furnace | |
Total Age | 620 °C (1150 °F) | 18hr | Air | |
No. 1 or Spring Temper | Anneal | 1010 °C (1850 °F) | 2hr | Air |
(for ISO 15156-3 / NACE MR 0175) | Age Harden | 790 °C (1455 °F) | 6hr | Air |
No. 1 Temper or Spring Temper | Age Harden | 720 °C (1330 °F) | 8hr | Furnace |
Total Age | 620 °C (1150 °F) | 18hr | Air |
The typical mechanical properties of Inconel® 718:
Annealed | ||
Approx. tensile strength | <1000 N/mm² | <145 ksi |
No. 1 Temper | ||
Approx. tensile strength | 1000 – 1200 N/mm² | 145 – 175 ksi |
Spring Temper | ||
Approx. tensile strength | 1250 – 1550 N/mm² | 180 – 225 ksi |
No. 1 Temper + Annealed + Aged | ||
Approx. tensile strength | 1250 – 1450 N/mm² | 181 – 210 ksi |
Approx. operating temperature depending on load^^ and environment | -200 to +550 °C | -330 to +1020 °F |
No. 1 Temper + Aged | ||
Approx. tensile strength | 1520 – 1720 N/mm² | 220 – 250 ksi |
Approx. operating temperature depending on load^^ and environment | Contact Alloy Wire Technical Dept |
Spring Temper + Annealed + Aged | ||
Approx. tensile strength | 1250 – 1450 N/mm² | 181 – 210 ksi |
Approx. operating temperature depending on load^^ and environment | -200 to +550 °C | -330 to +1020 °F |
Spring Temper + Aged | ||
Approx. tensile strength | 1700 – 1950 N/mm² | 247 – 283 ksi |
Approx. operating temperature depending on load^^ and environment | Contact Alloy Wire Technical Dept |