Reduction of Ni content in nickel-based alloys 

Although the nickel-based alloy has good corrosion resistance and excellent mechanical and physical properties, its wide application is limited by its high nickel content and high price. Reducing the Ni content of Ni-based alloys is one of the development directions of this alloy.

Compared with other series, Ni-Fe nickel-based alloys have a certain cost advantage because of the increase of Fe content, up to 45%, and the decrease of Ni content. This kind of alloy usually also contains Cr, Mo, Cu, Ti and Al and other elements, general Cr content is still as high as 20% or more, according to the ternary classification belongs to the Ni-Fe-Cr system. The launch of this type of alloy is used to fill the market demand for heat-resistant, corrosion-resistant alloys with relatively low nickel content. The main commercial series Incoloy series, typical grades are Incoloy800, 825, 864 and 925 and so on.

Incoloy800 (Ni: 30.0 ~ 35.0; Cr: 19.0 ~ 23.0; Fe: ≥ 39.5; C: ≤ 0.10; Al: 0.15 ~ 0.60; Ti: 0.15 ~ 0.60; Al + Ti: 0.30 ~ 1.20) is a single-phase austenitic alloy, due to higher high-temperature strength and oxidation, anti-carburization and other ncoloy 825 is a high-temperature corrosion resistant alloy, which has been widely used since its introduction. Typical applications include baskets, trays and fixtures in heat treatment equipment, heat exchangers and other piping systems used in chemical and petrochemical processes that require resistance to chloride stress corrosion, steam generator tubes in nuclear power plants, housings for electric heating elements in household appliances, heaters for cooking solutions in pulp production, heat exchangers in the petroleum industry and so on.

ncoloy825 is a solution reinforced alloy with added Mo, Cu and Ti Ni Fe Cr, which has excellent resistance to chloride stress corrosion cracking, pitting, crevice corrosion, handling and storage (such as sulfuric acid and phosphoric acid solutions) in reducing and oxidizing media. Reduced acids, nitric acids, nitrites and oxidizing media can also be used, as well as having excellent resistance to seawater corrosion. Typical applications include: heating tubes, vessels, water-cooled heat exchangers, sulfuric acid pickling in seafood piping systems, phosphoric acid production in heat exchangers, evaporators, cleaning and dip tube applications, air heat exchangers in oil refining, and flame retardant alloys for anaerobic applications.

Incoloy 864 is a high performance and cost effective Ni-Fe-Cr alloy specifically developed for use in automotive exhaust system fittings, exhaust recirculation pipes, manifolds and exhaust ducts. It has good fatigue resistance, thermal stability and resistance to salt corrosion, pitting and chloride stress corrosion cracking.

Incoloy 925 is an Al age-hardening alloy with Mo, Cu, Ti and Ni-Fe-Cr. Ni3 (Al, Ti) precipitates other intermediate phases with increasing temperature during the ageing process. The optimized alloys Ni, Cr, Mo, and Cu not only have good mechanical properties but also have a wide range of corrosion resistance, including resistance to chloride ion stress corrosion, stress corrosion, and localized corrosion in H2S acid gas environment. All kinds of reducing and oxidizing media have good corrosion resistance. The alloy has been widely used in aerospace, marine, energy and other industries, commonly used in the manufacture of oil and gas drilling equipment parts, such as pipes, valves, locating joints, joint drills, seal packers, etc., can also be used to make some fasteners.