Tuesday, 12 June 2018

In demand grades of Nickel-Chromium-Iron alloys


Inconel 600
Inconel 600 offers outstanding mechanical properties and high strength and supreme workability.  It adequately performs up to 1200oF. Inconel 600 resists corrosion in fresh waters, including the highly corrosive natural waters comprising of free carbon dioxide, iron compounds and dissolved air. It remains free from stress corrosion cracking in fact in boiling magnesium chloride.

Alloy 600 offers supreme resistance to sulfuric acid in the oxidizing conditions than Nickel 200 or Monel 400. Inclusion of oxidizing salts to sulfuric acid passivates Inconel 600 that makes it fit for use with acid mine waters where Monel  400 cannot be used.

Inconel 600 is not susceptible to stress corrosion cracking in the chloride salts and has supreme resistance to the nonoxidizing halides. It offers outstanding resistance to dry halogens at high temperatures and is used successfully in the chlorination plants up to 1000oF. This alloy replaces Nickel 201 in specifically high temperature applications where sulfur offers enhanced resistance.

Incoloy 800
It is basically used for oxidation resistance and strength at high temperatures. Alloy 800 is used in high temperature equipments because it does not develop the embrittling delta phase after long exposures up to 1600oF. It offers high creep and rupture strengths that add in its functionality in the numerous applications.


At moderate temperatures the general corrosion resistance of Incoloy 800 is similar to other austenitic nickel-iron-chromium alloys. With increase in temperature, alloy 800 attains supreme corrosion resistance whilst other austenitic steel grades fail to perform.

Incoloy 800 offers supreme resistance to nitric acid up to 70% concentrations. Its Inconel bars resist corrosion in diverseoxidizing salts however except halide salts. It offers good resistance to organic acids like formic, acetic and propionic acids. Incoloy 800 is specifically fit for use in hot corrosive gases.

Incoloy 825
Alloy 825 is an enhanced version of Incoloy 800 containing higher nickel concentration that makes it resistant to chloride ion stress corrosion cracking. Inclusions of molybdenum and copper resists pitting in the reducing conditions for example sulfuric or phosphoric acid. Incoloy 825 prevents corrosion in pure sulfuric acid solutions up to 40% concentrations at boiling points. However it has limited applications in hydrochloric or hydrofluoric acids.

Chromium concentration in Incoloy 825 resists corrosion in diverse oxidizing conditions like nitrates, nitric acid solutions and oxidizing salts. It resists corrosion by stress cracking in neutral chloride conditions. For localized corrosion of stainless steel 300 series, Incoloy 825 is the best replacement. It also prevents corrosion in seawater.

Incoloy 800H
Incoloy 800H is a controlled carbon grade of alloy 800. Carbon concentration is maintained between 0.05% to 0.1% to offer superior high temperature creep and stress rupture properties. It is also used in diverse high temperature applications in the refining and heat processing plants.


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