Inconel

What is Inconel?

Inconel is a trademark registered by Special Metals Corporation, referring to a family of nickel-based superalloys. These alloys, which contain a significant amount of chromium, are known for their excellent resistance to corrosion and oxidation, as well as their ability to retain mechanical properties at high temperatures. This makes them especially suitable for use in extreme environments such as the aerospace industry, chemical industry, and oil and gas sectors.

Composition of Inconel

The exact composition of Inconel alloys varies by type, but in general, they contain a high proportion of nickel (about 50–70%) and chromium (about 14–30%). Other possible alloying elements include molybdenum, niobium, iron, cobalt, manganese, copper, aluminum, and titanium. For example, Inconel 625 contains about 58% nickel, 20–23% chromium, 8–10% molybdenum, and 3.15–4.15% niobium, while Inconel 718 contains 50–55% nickel, 17–21% chromium, and 4.75–5.5% niobium and titanium. 

Properties of Inconel

Inconel alloys are renowned for their exceptional corrosion and oxidation resistance, making them ideal for use in extreme conditions. When heated, Inconel forms a thick and stable oxide layer on its surface that further protects the material from corrosion. In addition, Inconel retains its strength over a wide temperature range, which makes it suitable for high-temperature applications where materials like aluminum and steel may lose their strength. 

Uses of Inconel in the Engineering Industry

In the engineering industry, Inconel alloys are widely used for their excellent heat resistance and mechanical properties. They are particularly well-suited for components exposed to high temperatures and corrosion, such as turbine blades, nozzles, and exhaust manifolds. In addition, Inconel alloys are used in chemical reactors, steam generators in nuclear power plants, and drilling equipment in the oil and gas industry, where materials must withstand extreme conditions.

Machining Inconel in Workshops

The machinability of Inconel alloys is challenging due to their rapid work hardening. Machining is recommended to be done using efficient but slow methods to minimize the number of passes required. Ceramic tools can also be used effectively when working with Inconel. When welding, attention must be paid to the risk of cracking and segregation of alloying elements in the heat-affected zone, but certain grades of Inconel, such as 625 and 718, are designed to minimize these issues.

Summary

Inconel is a group of nickel-based superalloys that offer excellent resistance to corrosion and heat. The unique properties of these alloys make them valuable materials in the engineering industry, especially in applications where components are exposed to extreme conditions. Although machining Inconel can be challenging, with the correct methods and tools, high-quality results can be achieved, further increasing the use of these alloys in demanding industrial applications.