Glossary

Inconel is a family of nickel–chromium-based superalloys renowned for their exceptional strength, corrosion resistance, and ability to maintain structural integrity at extremely high temperatures. The name “Inconel” is a trademark originally registered by Special Metals Corporation, and it encompasses several specific alloys—such as Inconel 600, 625, 718, and 825—each tailored for different industrial applications.

At its core, Inconel’s strength lies in its nickel content (typically 50–70%), which provides outstanding resistance to oxidation, carburization, and corrosion, even in aggressive chemical or marine environments. The chromium enhances resistance to oxidation and scaling, while elements such as molybdenum, niobium, titanium, and aluminum improve mechanical strength and resistance to creep (deformation under stress at high temperatures).

What makes Inconel particularly valuable is its stability in extreme heat. Unlike many steels that lose strength or become brittle when exposed to high temperatures, Inconel alloys form a stable, adherent oxide layer that protects the surface from further degradation. This allows components made from Inconel to perform reliably at temperatures exceeding 1000°C (1832°F).

Because of these properties, Inconel is used in aerospace and gas turbine engines, where turbine blades, exhaust systems, and combustion liners are exposed to intense heat and corrosive gases. It’s also common in chemical processing, nuclear power plants, heat exchangers, offshore oil and gas equipment, and automotive turbochargers.

Among the common grades:

- Inconel 600 offers excellent resistance to oxidation and corrosion, especially in alkaline environments.

- Inconel 625 is known for superior corrosion resistance and strength due to its molybdenum and niobium content.

- Inconel 718, one of the most widely used, is precipitation-hardenable, providing extremely high tensile and fatigue strength up to about 700°C (1290°F).

In manufacturing, Inconel is notoriously difficult to machine due to its tendency to work-harden rapidly. Specialized cutting tools, slower machining speeds, and high coolant flow are typically required.