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Everything You Need To Know About Inconel 625

Views: 5     Author: Wang     Publish Time: 2024-04-03      Origin: Site

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Inconel 625 is a nickel-base alloy used both for its high strength and outstanding aqueous corrosion resistance. The strength of alloy 625 is primarily a solid solution effect from molybdenum and columbium. When this combines with molybdenum it distorts the alloy’s atomic matrix, thus providing particularly high strength in the annealed condition without a deliberate strengthening heat treatment. This combination of elements creates superior resistance to a wide range of corrosive environments of unusual severity.

Inconel 625 has excellent strength at temperatures up to 816℃. At higher temperatures, its strength is generally lower than that of other solid solution strengthened alloys. For long term service, it is best restricted to a maximum of 593℃, because long term exposure above 593℃ will result in significant embrittlement. Inconel 625 has good oxidation resistance at temperatures up to 980℃ and shows good resistance to aqueous corrosion, but is relatively moderate compared to other more capable corrosion resistant alloys. It achieves these levels of high strength as a result of the solid solution effects of molybdenum and niobium (also known as Colombium) from room temperatures up to 800°C. Alloy 625 is usually supplied in the hot worked and annealed condition.

Alloy 625 is generally supplied in the annealed condition, to provide utmost stability during fabrication and subsequent service. INCONEL 625 alloy has found to have a resistance to potable and salt or brackish water, where Chloride ions cause pitting and crevice corrosion to become established. As a result, pipelines for gathering sour gas have been built with solid (or clad) INCONEL 625 alloy and used in seawater heat exchangers in refineries, power plants, and offshore topside services that often need this material. Due to the high nickel content, Inconel Alloy 625 is immune to chloride-induced stress corrosion cracking. It also has good resistance to pitting and crevice corrosion.

 Chemical composition of Inconel 625

Inconel 625 is a high-performance nickel-chromium-molybdenum alloy known for its high level of strength, temperature resistance, and corrosion resistance. This superalloy is composed mainly of nickel (58% min.) followed by chromium, and molybdenum, niobium, iron, tantalum, cobalt, and trace amounts of manganese, silicon, aluminium, and titanium. Inconel 625 also commonly goes by the names: Haynes 625, Altemp 625, Nickelvac 625, and Nicrofer 6020.

Alloy 625 / Inconel 625 is used for its high strength, excellent fabricability (including joining), and outstanding corrosion resistance. It has become a standard material of construction in a wide variety of industrial applications, which is unusual for an alloy. Alloy 625 is valuable in that it is versatile and able to solve a wide variety of design and application problems. In order to be considered alloy 625, an alloy must have a certain chemical composition which includes: The chemical composition of Inconel 625 is: nickel (Ni) accounted for at least 63%, chromium (Cr) accounted for 20-23%, molybdenum (Mo) accounted for 8-10%, iron (Fe) accounted for less than 5%, copper (Cu) accounted for less than 0.5%, manganese (Mn) accounted for less than 0.5%, silicon (Si) accounted for less than 0.5%, phosphorus (P) accounted for less than 0.015%, sulfur (S) accounted for less than 0.015%, carbon (C) accounted for less than 0.015%. below, carbon (C) accounted for less than 0.1%, aluminium (Al) accounted for less than 0.4%, titanium (Ti) accounted for less than 0.4%, and the remaining amount is nickel (Ni).

 Inconel 625

Features of Inconel 625

The strength of UNS N06625 lies not only in its nickel-chromium base but also the hardening mechanism of niobium and molybdenum. The alloy matrix is strengthened by the interaction of niobium with molybdenum that offers high strength without the need for precipitation-hardening treatment. The tensile strength of this superalloy is 690 MPa, while its yield strength measures 275 MPa.

High temperature resistance

With a melting point of about 1300°C and a thermal expansion coefficient of 1.28 x 10-5 1/K (at 20°C), Inconel 625 resists a wide range of temperature extremes from cryogenic to extremely high. At high temperatures in the presence of oxidising agents, the titanium and niobium compositions of the oxide film on Inconel 625 increase drastically to form a natural protective layer in the material.

Corrosion resistance

The unique combination of its components makes Inconel 625 highly resistant to corrosive substances. This is the reason why this superalloy works excellently under high saline seawater, and more so in milder environments such as fresh water and standard atmospheric conditions. Upon exposure to oxidising agents, Inconel 625 is protected naturally by its nickel-chromium matrix. Meanwhile, molybdenum protects the material against pitting corrosion. In 15% sulfuric acid, the material corrodes at a minimal rate of 0.188 mm per year.

High level of fabricability

Inconel 625 was designed to have better weldability than earlier alloys, with no signs of cracking when exposed to strain and temperature changes post-welding. Its high creep resistance and yield strength make this superalloy a good choice for tubes, piping, and plant equipment that require welding.

Applications of Inconel 625

Marine applications

Owing to its high corrosion resistance-- especially pitting and crevice resistance, Inconel 625 is an ideal for high saline, underwater applications. The material is used as propeller blades for boats, mooring lines to secure ships and similar vessels, accessories and fixtures for submarines, and parts for oceanographic equipment.

Aerospace equipment

The superalloy has also found its way into the aircraft industry, particularly for exhaust equipment, fuel lines, heat exchanger casings, and rocket components. This is because Inconel 625 works well even in extreme temperatures under high stress.

Nuclear technology

Its strength as well as its resistance to corrosion and stress make Inconel 625 a suitable component of nuclear reactors, particularly in the control rod and reactor core. Nuclear systems also generally involve high temperatures beyond 650°C, in which the strength of Inconel 625 can withstand.

Industrial processing

Because the alloy is conveniently fabricable and resistant to heat and corrosion, it is a useful ingredient in the production of manufacturing equipment such as vessels, heat exchangers, valves, and fluid distribution systems. Its excellent weldability also makes it a suitable component for pipes and tubes used in manufacturing plants.

JN Alloy is a distributor and product manufacturer of stainless steel, duplex steel, and nickel.
Tel: +86 19339900211
Add: Stainless steel Market 289, Xinwu District , Wuxi, China
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