When considering materials for high performance in demanding applications, the name Inconel springs to mind. Because Inconel is very expensive, its application is limited. As a result, Inconel is less well-known than steel or aluminum. This article will go over the fundamentals of this one-of-a-kind nickel alloy.
What is Inconel?
Inconel alloys are nickel-chrome superalloys. Inconel has excellent corrosion resistance, oxidation resistance, high-temperature strength, and creep resistance. Inconel is resistant to high temperatures and extremely corrosive environments.
Special Metals Corporation, USA owns the registered trademark “Inconel.” The first Inconel alloy was created in 1932.
Composition of Inconel Alloy
The chemical composition of Inconel varies according to grade. Because this is a nickel allowance, the nickel percentage is higher. Other elements found in Inconel alloy material include:
- Chromium
- Iron
- Cobalt
- Molybdenum
- Titanium
- Niobium
Properties of Inconel Material
Inconel is characterized by its ability to withstand extremely high temperatures. Even at high temperatures, Inconel alloy retains its strength. When heated, a thick and stable protective oxide layer forms, providing excellent corrosion resistance even at high temperatures. Inconel material is an excellent choice for extremely high-temperature applications where steel material succumbs to creep.
The formation of an intermetallic compound Ni3Nb in the gamma double prime (“) phase is primarily responsible for Inconel’s extremely high-temperature resistance. When heated to high temperatures, this intermetallic phase acts as a ‘glue’ on the grain boundaries, preventing the grains from growing in size. At high temperatures, Gamma prime forms small cubic crystals that effectively inhibit slip and creep.
Material Grades of Inconel Alloy
Inconel material comes in a variety of grades, each with its composition and properties tailored to specific applications. The following are the most common Inconel grades:
- Inconel 188: This alloy is widely used in commercial gas turbine and aerospace applications.
- Inconel 230: This material is primarily used in the power, aerospace, chemical processing, and industrial heating industries.
- Inconel 600: Fortified solid solution.
- Inconel 601
- Inconel 617: A high-temperature nuclear alloy used in ASME Boiler and Pressure Vessel Code applications such as molten salt reactors.
- Inconel 625 is acid resistant and weldable.
- Inconel 690: Used in nuclear applications and has a low resistivity.
- Inconel 706
- Inconel 718 is a gamma double prime strengthened alloy with good weldability.
- Inconel 907
- Inconel 909
- Inconel X-750: This material is widely used in gas turbine components such as blades, seals, and rotors.
- Inconel 751: Increased aluminum content for improved rupture strength in the 1600 °F range.
- Inconel 792: Added with more aluminum for improved high-temperature corrosion resistance, particularly in gas turbines.
- Alloy 825
- Inconel 925: Inconel 925 is a low carbon content non stabilized austenitic stainless steel.
- Inconel 939: Gamma prime strengthened to increase weldability.
Applications of Inconel Material
UNS N06625, Werkstoff Number 2.4856, and ISO NW6625 are all designations for INCONEL alloy. Inconel is listed in the NACE MR-01-75 standards. All standard mill forms of Inconel material are manufactured, including rod, bar, wire, wire rod, plate, sheet, strip, shapes, pipes, tubular products, and forging stock.
The aerospace industry is the most common application for Inconel alloys. Inconel is used in the space shuttle, rocket engines, 3D printing technology, and other applications. The nuclear industry also makes extensive use of various Inconel grades. Other applications for Inconel alloys include:
- Jet engines
- Fuel Nozzles
- Engine Parts
- Afterburner Rings
- Marine applications in saltwater
- Extraction of Oil and Gas