Alloy 718

Definition - What does Alloy 718 mean?

Alloy 718 is a nickel-based metal alloy that is known for its corrosion resistance and ability to be heat-treated. In addition to nickel, it also has relatively high amounts of iron, cobalt and chromium.

Corrosionpedia explains Alloy 718

Alloy 718 has a high degree of corrosion resistance thanks to high amounts of nickel. It also has high amounts of chromium, which helps the iron in its composition resist oxidation.

Alloy 718 is readily weldable, partly because it is not very susceptible to post-weld cracking. While it is unlikely to crack following welding, additional heat treatments such as annealing and artificial aging should be used afterwards so that the mechanical properties are restored.

Alloy 718 can be heat-treated at temperatures around 1900°F (1040°C). Alloy 718 can also be aged at around 1450°F (790°C). Since it is artificially aged around this temperature, its maximum operating temperature is around 1300°F (704°C) so that it does not become vulnerable to overaging.

Alloy 718 can also have its strength increased through work hardening procedures. In its annealed condition alloy 718 has a yield strength of about 150,000 psi. However, it is not very ductile, with percent elongations of around 10.

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