As a superalloy designed by Special Metals CorporatioInconel is a superalloy designed by Special Metals Corporation. It has unique properties that make it highly favored by fabricators in various industries (XMAKE is one of them).
While 625 and 718 are the two most popular types of Inconel, it is important to remember that this alloy has many different subtypes, each used for different industrial applications.
This article will explore the various common Inconel alloy types.
Inconel Alloy
Inconel alloy is a family of austenitic nickel-chromium alloys known for their exceptional resistance to extreme environments.
Chemical Composition and Mechanical Properties of Inconel
There are many categories of Inconel, and the table you see here is an example of Inconel 600:
| Inconel 600 | |
| Appearance |
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| Chemical Composition |
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| Density | 8.47 g/cm³ |
| Melting Point | 1320-1425°C |
| Thermal Conductivity | 13.3 W/(m·K) |
| Tensile Strength | ≥1030 MPa |
| Stiffness | Usually around 200 GPa |
| Glass Transition Temperature | Metal alloys have no specific Tg |
| Corrosion Resistance | Resistant to corrosion by inorganic acids and chloride media in oxidizing and reducing environments |
| Thermal Stability | Exhibits good oxidation resistance at high temperatures |
| Malleability | Maintain excellent mechanical properties after welding without cracking |
| Specific Heat Capacity |
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| Thermal Diffusivity |
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| Electrical Resistivity |
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| Aerospace Application |
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| Marine Application |
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| Electrical Application |
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| In Chemical Processing |
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How are Inconel alloys made?
Inconel are high-performance materials primarily composed of nickel, chromium, and iron, known for their exceptional resistance to heat and corrosion.
- Material Selection: The manufacturing process begins with carefully selecting raw materials, which are melted together in a furnace.
- Cleaning and melting: This is typically done using vacuum induction melting to avoid contamination and ensure a uniform composition.
- Casting: Once the metal components are melted, they are cast into molds to form ingots.
- Heating and Cooling: These ingots undergo a series of processes including hot working and cold working to refine their structure and enhance their mechanical properties.
- Heat treatment: Further optimize their mechanical properties and corrosion resistance.
- Hot working: Involves heating the metal to a pliable temperature, allowing it to be shaped.
- Cold working: Performed at room temperature to increase strength through strain hardening.
Inconel 601
Inconel 601 is a high-performance nickel alloy known for:
Advantage
- Exceptional corrosion and oxidation resistance
- Improved durability and stability in extreme conditions
- Resistance to sulfur compounds
- Capable of withstanding thermal cycling without significant degradation
- Maintain mechanical strength and structural integrity at elevated temperatures
Composition
| Element | Content range (%) |
| Nickel (Ni) | 58.0 – 63.0 |
| Chromium (Cr) | 21.0 – 25.0 |
| Iron (Fe) | Residual composition |
| Aluminum (Al) | 1.0 – 1.7 |
| Carbon (C) | ≤ 0.10 |
| Manganese (Mn) | ≤ 1.0 |
| Sulfur (S) | ≤ 0.015 |
| Silicon (Si) | ≤ 0.50 |
| Copper (Cu) | ≤ 1.0 |
Application
This alloy is often used in:
- Trays, baskets, and jigs in heat treatment plants
- Radiant tubes, wire mesh tapes, high-temperature heating tubes
- Catalyst support grids, isolation tanks
- Propulsion systems and jet pipes
Inconel 617
Inconel 617 is a nickel-chromium-cobalt alloy.
Advantage
- Exceptional thermal stability(retain its mechanical strength at temperatures exceeding 1,000 °F/538 °C)
- Corrosion resistant
- Particularly valuable in demand reliability in extreme environments
- Excellent weldability and fabricability
Composition
| Element | Content range (%) |
| Nickel(Ni) | 44.5 min |
| Chromium (Cr) | 20.0 – 24.0 |
| Cobalt (Co) | 10.0 – 15.0 |
| Molybdenum (Mo) | 8.0 – 10.0 |
| Aluminum (Al) | 0.8 – 1.5 |
| Carbon (c) | 0.05 – 0.15 |
| Iron (Fe) | ≤ 3.0 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 1.0 |
| Sulfur (S) | ≤ 0.015 |
| Titanium (Ti) | ≤ 0.6 |
| Copper (Cu) | ≤ 0.5 |
| Boron (B) | ≤ 0.006 |
Application
- Spacecraft combustion tanks
- High-temperature components in heat exchanger and reformer piping
- Catalyst tubes in ethylene production
- Fuel cores in nuclear reactors
- Catalyst grid support in nitric acid production
Inconel 625
Advantage
Inconel® 625 is a high-performance nickel-chromium-molybdenum alloy known for its:
- Exceptional resistance to corrosion and oxidation
- Maintain strength and stability at elevated temperatures
- Excellent weldability
- Aesthetic appeal from fabrication characteristics
- Easy integration into various components
Composition
| Element | Content range (%) |
| Nickel (Ni) | min 58.0 |
| Chromium (Cr) | 20.0 – 23.0 |
| Molybdenum (Mo) | 8.0 – 10.0 |
| Niobium (Nb) | 3.15 – 4.15 |
| Iron (Fe) | ≤ 5.0 |
| Aluminum (Al) | ≤ 0.40 |
| Titanium (Ti) | ≤ 0.40 |
| Carbon (C) | ≤ 0.10 |
| Manganese (Mn) | ≤ 0.50 |
| Silicon (Si) | ≤ 0.50 |
| Sulfur (S) | ≤ 0.015 |
| Phosphorus (P) | ≤ 0.015 |
| Cobalt (Co) | ≤ 1.0 |
Application
Inconel alloy 625 is particularly suited for extreme environments, including:
- Pressure vessels
- Space engine magazines
- Nuclear power steam generator
- Ship Structural Components in seawater
Inconel 718
Advantage
Inconel® 718 is one of the superalloys known for:
- Exceptional strength and resistance to extreme temperatures and corrosive environments
- Withstand high-stress conditions while maintaining structural integrity
- Can be heat-treated to achieve high tensile and yield strength
- Excellent weldability
- Allows for complex geometries
Composition
| Element | Content range (%) |
| Nickel (Ni) | min 58.0 |
| Chromium (Cr) | 20.0 – 23.0 |
| Molybdenum (Mo) | 8.0 – 10.0 |
| Niobium (Nb) | 3.15 – 4.15 |
| Iron (Fe) | ≤ 5.0 |
| Aluminum (Al) | ≤ 0.40 |
| Titanium (Ti) | ≤ 0.40 |
| Carbon (C) | ≤ 0.10 |
| Manganese (Mn) | ≤ 0.50 |
| Silicon (Si) | ≤ 0.50 |
| Sulfur (S) | ≤ 0.015 |
| Phosphorus (P) | ≤ 0.015 |
| Cobalt (Co) | ≤ 1.0 |
Application
Alloy 718 is often used in:
- Elastic elements and grids for the nuclear industry
- Combustion chamber vapors for spacecraft
- Turbines and liquid-fueled rockets
- Downhole tools and valves for oil drilling
- This is also one of XMAKE’s common materials for 3D Printing.
Inconel 725
Advantage
This is a high-performance alloy of nickel and chromium known for:
- Corrosion-resistant, especially avoid crevice corrosion
- Good mechanical properties at room temperature
- Maintain high tensile strength at high temperatures that undergo thermal cycling
- Allowing for easy fabrication and integration into complex systems
- Less maintenance costs and high operational efficiency
Composition
| Element | Content range (%) |
| Nickel (Ni) | 55.0 – 59.0 |
| Chromium (Cr) | 19.0 – 22.5 |
| Molybdenum (Mo) | 7.0 – 9.5 |
| Tantalum (Ta)/Niobium (Nb) | 2.75 – 4.0 |
| Titanium (Ti) | 1.0 – 1.7 |
| Aluminum (Al) | ≤ 0.35 |
| Carbon (C) | ≤ 0.03 |
| Manganese (Mn) | ≤ 0.35 |
| Silicon (Si) | ≤ 0.20 |
| Sulfur (S) | ≤ 0.015 |
| Phosphorus (P) | ≤ 0.01 |
| Copper (Cu) | ≤ 0.35 |
Application
- Oil Wellhead Equipment
- Firewalls and blast walls for desalination plants
- Marine fittings, couplings and bearings
This type of Inconel alloy is also valued in components for applications in environments containing hydrosulfides and chlorides (e.g. chemical industry).
Inconel x-750
Advantage
- Exceptional resistance to oxidation
- Good thermal creep deformation
- Maintains integrity and safety under extreme conditions
- Withstand corrosion from various aggressive environments, including sulfuric and hydrochloric acids
- weldability and ease of fabrication
Composition
| Element | Content range (%) |
| Carbon (C) | ≤ 0.08 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 0.50 |
| Sulfur (S) | ≤ 0.01 |
| Chromium (Cr) | 14.00 – 17.00 |
| Nickel (Ni) | ≥ 70.00 |
| Niobium (Nb/Cb) | 0.70 – 1.20 |
| Titanium (Ti) | 2.25 – 2.75 |
| Aluminum (Al) | 0.40 – 1.00 |
| Iron (Fe) | 5.00 – 9.00 |
| Cobalt (Co) | ≤ 1.00 |
| Tantalum (Ta) | ≤ 0.05 |
| Copper (Cu) | ≤ 0.50 |
Application
- Rotor blades
- Impeller
- Bolted rocket motor thrust chambers
- Springs and fasteners
- Thrust reversers and hot air ductwork in aircraft structures
825 Inconel
Advantage
- Particularly effective in harsh environments
- Withstand reducing conditions
- Maintain structural integrity even under high stress and temperature variations
- High strength and ductility
- weldable in complex assemblies and structures
Composition
| Element | Content range (%) |
| Nickel (Ni) | 38.0 – 46.0 |
| Iron (Fe) | ≥ 22.0 |
| Chromium (Cr) | 19.5 – 23.5 |
| Molybdenum (Mo) | 2.5 – 3.5 |
| Copper (Cu) | 1.5 – 3.0 |
| Titanium (Ti) | 0.6 – 1.2 |
| Carbon (C) | ≤ 0.05 |
| Manganese (Mn) | ≤ 1.0 |
| Sulfur (S) | ≤ 0.03 |
| Silicon (Si) | ≤ 0.5 |
| Aluminum (Al) | ≤ 0.2 |
Application
- Oil and gas well pipelines and petrochemical pipelines
- Nuclear Fuel Reprocessing Equipment
- Acid production and pickling equipment
- Pollution control equipment
Contact Us for inconel® CNC Machining
As the world’s leading digital manufacturing platform, XMAKE regards Inconel as an ideal material for CNC machining, and suitable for applications like automotive, aerospace, medical devices, robotics, and consumer products.
If you need service in any of these areas, you can click this link for an instant quote.
FAQ
Q1: What are the key properties of Inconel compared to stainless steel?
A: Inconel are known for their excellent resistance to oxidation and corrosion, making them suitable for extreme environments. Unlike 316 stainless steel, Inconel can withstand high temperatures and pressures, which is ideal for applications in the aerospace industry and oil and gas extraction.
Q2: How does Inconel perform in cryogenic applications?
A: Inconel maintains its mechanical properties even at cryogenic temperatures. They exhibit high strength and good ductility, which are essential for applications in cryogenic environments such as liquefied natural gas (LNG) storage and transportation.
Q3: What is the significance of precipitation hardening in Inconel?
A: Precipitation hardening is a process used to enhance the strength of Inconel. This process involves the formation of small particles within the metal matrix, which impede dislocation movement. The results with improved rupture strength and overall performance in high-stress environments.
Q4: How does Inconel compare to Monel in terms of corrosion resistance?
A: Inconel provides superior resistance to oxidation and corrosion in high-temperature applications. Monel 400, on the other hand, is more effective in reducing sulfuric and hydrochloric acids.
Q5: How does Inconel perform against pit corrosion?
A: Inconel shows remarkable resistance to pit corrosion, particularly when compared to standard stainless steel. Their unique composition and microstructure help prevent pit formation, making them suitable for use in harsh environments such as marine and chemical processing applications.
Reference
- Inconel718 nickel-chromium high temperature alloy – inconel|Inconel Series – Shanghai Boshiman Special Steel Group Co. c276,825,,600,625,718,254smo Imported stainless steel domestic stainless steel. Shanghai Bohemian Special Steel Group Co. (n.d.). http://www.021bxm.com/index.php?m=content&c=index&a=show&catid=22&id=14&ugjctc=ueaym1
- Inconel 600-Shanghai Honglong Metal Materials Co. (n.d.). https://www.hloem.com/productinfo/1316099.html
