Today both Inconel and Incoloy are widely used in various spheres but still many of us don’t know the basic difference between the two. Both Inconel and Incoloy belong to the family of superalloys, also called high-performance alloys but both have their own distinct properties, and offer high resistance to corrosion and oxidation, in addition to mechanical strength at elevated temperatures.

When comparing the differences the most basic difference between them is their composition. Inconel is an alloy of nickel-chrome and usually contains over 50 percent nickel, whereas Incoloy, is an alloy of nickel-iron-chromium, and contains less than 50 percent nickel content.

Let us know more about the differences between the two alloys in detail.

Inconel

Inconel, once heated, forms a thick yet stable oxide layer that protects its outer surface from an additional attack. This makes it the perfect alternative for high temperature and pressure applications, where steel and aluminum would succumb to thermal creep. Available in various grades, the Inconel alloys exhibit shifting characteristics with slight variations in their chemistry.

In its more basic type, typical applications would include the food industry and heat treated components. Once alloyed with different elements, however, additional strengthening and stiffening allow its use in the more stringent areas of the marine, aerospace, and chemical processing industries. Alloyed to its highest performance, Inconel then becomes the choice material of in the most crucial environments of turbine blades, rocket engines, and key nuclear industry components.

Characteristics of Inconel alloys are as follows:

Good resistance to acids, such as sulfuric, phosphoric, nitric, and hydrochloric

Almost completely free from chloride-induced stress corrosion cracking

Outstanding mechanical properties at both extremely low and high temperatures

Excellent pitting, crevice corrosion, and intercrystalline corrosion resistance

High resistance to oxidation at elevated temperatures

Applications, where Inconel alloys are used, are as follows:

Chemical and petrochemical processing

Flare stacks on offshore oil platforms

Gas turbines, rocket motors/engines, and spacecraft

Pollution control equipment

Nuclear reactors

Incoloy

Incoloy, with its higher ferrous content and correspondingly lower cost, make it the ideal material in elevated temperature, but less critical, applications. A further feature is its relative ease of fabrication, employing the same machines and processes used for stainless steel.

Incoloy alloy also comes in a variety of grades, whose emphasis is more on resistance to aggressive forms of corrosion, particularly in aqueous environments. Whereas a basic form of Incoloy will find widespread general use, further alloying with enhancing elements provides added resistance to chemical and environmental corrosion, as well as physical deterioration, such as surface pitting and cracking.

Excellent resistance to seawater, brine, sour gas and high chloride environments make it a popular choice in the oil and gas industries. The most specialized Incoloy alloys, however, are widely used in the harshest chemical environments of all, involving among others, acids, wet scrubbing, nuclear fuel and the reactive atmospheres of furnaces.

Characteristics of Incoloy alloy are as follows:

Excellent strength resistance in high-temperature settings

Outstanding oxidation and carburization resistance in high-temperature settings

Good creep-rupture strength

Good corrosion resistance in aqueous environments

Ease of fabrication

Applications, where Incoloy alloys are used, are as follows:

carburizing equipment, heating-element sheathing, process piping, heat exchangers, nuclear steam-generator tubing,

heat-treating equipment, chemical and petrochemical processing, power plants, industrial furnaces,

oil, and gas well piping, nuclear fuel reprocessing, acid production, pickling equipment.

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