Introduction
Inconel 625 (UNS designation N06625) is a nickel-based superalloy possessing excellent resistance to oxidation and corrosion over a wide range of corrosive conditions including atmospheric exposure, neutral and alkaline salt solutions, and both organic and inorganic acids. It is a highly alloyed component with the base composition of nickel (58%) along with the addition of chromium, iron, and molybdenum. It has the chemical composition of Ni-22Cr-9Mo-3.8Nb-3.2Ti-0.3Al-0.15C-0.02Fe by weight.
Corrosion Resistance
Inconel 625 is characterized by outstanding resistance to rust and corrosion, offering a combination of creep strength, metal strength, and resistance in a broad range of environments. In such conditions, many other materials either corrode or weaken. High nickel content as well as the presence of certain metals such as molybdenum and chromium in its composition provides superior corrosion and oxidation resistance than other commonly used materials. Against neutral solutions of sodium chloride and seawater, it displays excellent resistance to chloride-induced pitting and crevice corrosion. Its extreme thermal stability and excellent ductility and toughness at both cryogenic and elevated temperatures make the material suitable for a wide variety of applications including those involving elevated temperatures.
Mechanical Properties
Inconel 625 is a superalloy with outstanding mechanical strength, particularly in terms of its yield and tensile strengths, which are exceptionally high compared to other alloys. At room temperature, it has a yield strength of 764MPa (111 ksi), a tensile strength of 1000-1130 MPa (145-163 ksi), and an elongation of 48-50%. Additionally, Inconel 625 has excellent fatigue strength, ductility, and charpy impact strength.
Weldability
The weldability of Inconel 625 is excellent. It can be easily welded by conventional welding processes, including gas tungsten arc welding, gas metal arc welding, shielded metal arc welding, and electron beam welding. It can also be welded together with its own type or compatible alloys, and because of its good oxidation resistance, welding also forms an efficient heat treatment.
Applications
Inconel 625 is used for a wide range of applications. It is primarily used for components and parts requiring superior strength and a long life, such as jet engine components, aircraft parts, motorcycle and automotive parts, springs, and fasteners. Other uses include power plants, petrochemical and chemical industries, valves, fittings, and pumps.
Conclusion
Inconel 625 is an extremely corrosion and oxidation resistant nickel-based superalloy that has excellent strength and mechanical properties. Its excellent corrosion and oxidation resistance makes it suitable for a wide range of applications including aircraft parts, components, and fasteners. Its weldability is also excellent, making it easy to weld using conventional welding processes. Inconel 625 is a popular and cost-effective material for a variety of industrial and consumer applications.
