Difference Between Inconel and Incoloy

What is the Difference Between Inconel® and Incoloy®?

Although Inconel® and Incoloy® belong to the same family of superalloys, each possesses its own distinct properties, as well as sharing others. Also known as high-performance alloys, the superalloys in general provide high resistance to corrosion and oxidation, as well as mechanical strength at elevated temperatures.

The most fundamental of difference between them lies in their composition. Inconel®, predominantly of nickel-chrome, generally contains over 50% nickel, whereas Incoloyl®, a nickel-iron-chromium alloy, has less than 50% nickel content.

What are the Characteristics of Inconel?

Good resistance to acids, such as sulfuric, phosphoric, nitric, and hydrochloric
Almost completely free from chloride induced stress corrosion cracking
Excellent mechanical properties at both extremely low and extremely high temperatures
Outstanding resistance to pitting, crevice corrosion and intercrystalline corrosion
High resistance to oxidation at elevated temperatures

In what Applications are Inconel alloys used?

Chemical and petrochemical processing
Components where exposure to high mechanical stress and sea water are required
Flare stacks on offshore oil platforms
Gas turbines, rocket motors/engines, and space craft
Pollution control equipment
Nuclear reactors

On a more specific level, the major distinctions between the two are their applications and spheres of suitability.

Inconel®
Inconel®, when heated, forms a thick yet stable oxide layer that protects its outer surface from further attack. This makes it the ideal choice for extreme temperature and pressure applications, where steel and aluminum would succumb to thermal creep. Available in numerous grades, the Inconel® alloys exhibit shifting characteristics with slight variations in their chemistry.

In its more basic form, typical applications would include the food industry and heat treatment components. When alloyed with other elements, however, further strengthening and stiffening permits its use in the more demanding areas of the marine, aerospace and chemical processing industries. Alloyed to its peak performance, Inconel then becomes the material of choice in the most critical environments of turbine blades, rocket engines and key nuclear industry components.

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.

This 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.

Inconel

Inconel® is a registered trademark (of Special Metals Corporation) referring to a family of austenitic nickel-chromium super alloys. Inconel® is a material that is specifically optimized for some of the toughest use conditions to be found in manufacturing while Titanium is a chemical element with symbol Ti and atomic number 22. It is a lustrous transition metal with a silver color, low density, and high strength.

Inconel Material Specification

Inconel 600
Solid solution strengthened.
Inconel 601
Inconel 625
Acid resistant, good weldability. The LCF version is typically used in bellows. Ideal for hardware and components in the power, aerospace and chemical processing industries. Offered in sheet, plate, bar and forgings.
Inconel 718
Gamma double prime strengthened with good weldability. The preferred material for cryogenic storage tanks, turbines, downhole shafts and wellhead parts offered in sheet, plate and bar.
Inconel X750
Commonly used for gas turbine components, including blades, seals and rotors.
Inconel 907
Inconel 909
Inconel 706
Inconel 617
Inconel 751
Increased aluminium content for improved rupture strength in the 1600 °F range.
Inconel 792
Increased aluminium content for improved high temperature corrosion properties, used especially in gas turbines.
Inconel 939
Gamma prime strengthened to increase weldability.
Inconel 188
Readily fabricated for commercial gas turbine and aerospace applications. Offered in sheet, plate and bar.
Inconel 690
Low cobalt content for nuclear applications, and low resistivity.
Inconel 713C
Precipitation hardenable nickel-chromium base cast alloy.
Inconel 230
Inconel 230 Plate & Sheet mainly used by the power, aerospace, chemical processing and industrial heating industries, Aerospace Materials.

Inconel Composition

Inconel	Element (% by mass)
Inconel	Ni	Cr	Fe	Mo	Nb	Co	Mn	Cu	Al	Ti	Si	C	S	P	B
600	72.0	14.0–17.0	6.0–10.0				1.0	0.5			0.5	0.15	0.015
617	44.2–56.0	20.0–24.0	3.0	8.0–10.0		10.0–15.0	0.5	0.5	0.8–1.5	0.6	0.5	0.15	0.015	0.015	0.006
625	58.0	20.0–23.0	5.0	8.0–10.0	3.15–4.15	1.0	0.5		0.4	0.4	0.5	0.1	0.015	0.015
690	59.5	30	9.2				0.35	0.01	0.02		0.35	0.019	0.003
718	50.0–55.0	17.0–21.0	balance	2.8–3.3	4.75–5.5	1.0	0.35	0.2–0.8	0.65–1.15	0.3	0.35	0.08	0.015	0.015	0.006
X-750	70.0	14.0–17.0	5.0–9.0		0.7–1.2	1.0	1.0	0.5	0.4–1.0	2.25–2.75	0.5	0.08	0.01

Inconel alloys

Alloys of inconel include:

Inconel 600: Solid solution strengthened
Inconel 601
Inconel 625: Acid resistant, good weldability. The LCF version is typically used in bellows.
Inconel 690: Low cobalt content for nuclear applications, and low resistivity
Inconel 713C: Precipitation hardenable nickel-chromium base cast alloy
Inconel 718: Gamma double prime strengthened with good weldability
Inconel 751: Increased aluminium content for improved rupture strength in the 1600 °F range
Inconel 792: Increased aluminium content for improved high temperature corrosion properties, used especially in gas turbines
Inconel 939: Gamma prime strengthened to increase weldability

Inconel Equivalent Grades

STANDARD	WERKSTOFF NR.	UNS	GOST	AFNOR	JIS	BS	EN	OR
Inconel 600	2.4816	N06600	МНЖМц 28-2,5-1,5	NC15FE11M	NCF 600	NA 13	NiCr15Fe	ЭИ868
Inconel 601	2.4851	N06601	XH60BT	NC23FeA	NCF 601	NA 49	NiCr23Fe	ЭИ868
Inconel 617	2.4663	N06617
Inconel 625	2.4856	N06625	ХН75МБТЮ	NC22DNB4M	NCF 625	NA 21	NiCr22Mo9Nb	ЭИ602
Inconel 690	2.4642	N06690
Inconel 718	2.4668	N07718
Inconel 725	-	N07725
Inconel X-750	2.4669	N07750

Inconel Melting Point, Density and Tensile Strength

	Density	Melting Point	Tensile Strength	Yield Strength (0.2%Offset)	Elongation
600	8.47 g/cm3	1413 °C (2580 °F)	Psi – 95,000 , MPa – 655	Psi – 45,000 , MPa – 310	40 %
601	8.1 g/cm3	1411 °C (2571 °F)	Psi – 80,000 , MPa – 550	Psi – 30,000 , MPa – 205	30 %
617	8.3g/cm³	1363°C	≥ 485 MPa	≥ 275 MPa	25 %
625	8.4 g/cm3	1350 °C (2460 °F)	Psi – 135,000 , MPa – 930	Psi – 75,000 , MPa – 517	42.5 %
690	8.3g/cm³	1363°C	≥ 485 MPa	≥ 275 MPa	25 %
718	8.2 g/cm3	1350 °C (2460 °F)	Psi – 135,000 , MPa – 930	Psi – 70,000 , MPa – 482	45 %
725	8.31 g/cm3	1271°C-1343 °C	1137 MPa	827 MPa	20 %
X-750	8.28 g/cm3	1430°C	1267 MPa	868 MPa	25 %

Incoloy

Incoloy refers to a range of superalloys produced by the Special Metals Corporation group of companies.

Incoloy Compositions (percentages)

Alloy name	Balance metal	Chromium	Aluminum	Titanium	Carbon	Yttrium oxide	Copper	Manganese	Cobalt	Nickel	Phosphorus	Silicon	Sulphur	Molybdenum	Nb+Ti
020	Fe (~40%)	20	n/p	n/p	<0.07	n/p	3.5	<2.0	n/p	35	<0.045	<1.0	<0.035	2.5	about 1
DS	Fe (~40%)	18	n/p	0.2	0.1	nil	0.5	0.8-1.5	18 (Co+Ni 38)	18 (Co+Ni 38)	n/p	2.3	0.03
MA956	Fe (~75%)	20	4.75	0.4	<0.1	0.5	<0.15	<0.3	<0.3	<0.5	<0.02	n/p	n/p