Inconel 718 round bar is one of the most versatile and widely used nickel-chromium alloys. Known for its exceptional strength, corrosion resistance, and high-temperature stability, it is a preferred choice in industries such as aerospace, power generation, marine, and chemical processing. This alloy not only withstands extreme conditions but also offers long-term durability, making it one of the most trusted materials for critical engineering applications.
In this blog, we will explore the properties, specifications, applications, and benefits of Inconel 718 round bar in detail.
What is Inconel 718?
Inconel 718 is a precipitation-hardened nickel-based superalloy. It contains nickel, chromium, molybdenum, niobium, and trace amounts of titanium and aluminum. The alloy is specially designed to maintain excellent strength and toughness even at temperatures as high as 1300°F (704°C). Unlike many other nickel alloys, Inconel 718 also offers outstanding weldability, which makes it easy to fabricate into different shapes such as rods, bars, and sheets.
The addition of niobium and molybdenum strengthens the alloy while enhancing its resistance to creep and stress rupture. Chromium ensures resistance to oxidation and corrosion in challenging environments. This unique combination of elements makes Inconel 718 round bar a highly reliable material for demanding industries.
Chemical Composition of Inconel 718 Round Bar
The chemical composition of Inconel 718 contributes to its superior mechanical and chemical properties:
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Nickel (Ni): 50–55%
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Chromium (Cr): 17–21%
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Iron (Fe): Balance
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Niobium (Nb) + Tantalum (Ta): 4.75–5.5%
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Molybdenum (Mo): 2.8–3.3%
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Titanium (Ti): 0.65–1.15%
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Aluminum (Al): 0.2–0.8%
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Carbon (C): 0.08% max
This blend ensures excellent resistance to both high-temperature oxidation and aqueous corrosion.
Mechanical Properties of Inconel 718 Round Bar
The mechanical properties of Inconel 718 bar make it suitable for use in extreme conditions:
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Density: 8.19 g/cm³
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Melting Point: 1260–1336°C
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Tensile Strength: 1240 MPa min
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Yield Strength (0.2% Offset): 1035 MPa min
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Elongation: 12% min
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Hardness: 331 HB
These properties allow the alloy to maintain strength under high pressure and temperature without deformation.
Key Features of Inconel 718 Round Bar
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High Strength: Maintains superior tensile and yield strength even in high-pressure environments.
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Corrosion Resistance: Offers excellent resistance against pitting, crevice corrosion, and oxidation.
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High-Temperature Stability: Performs well in temperatures up to 704°C.
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Excellent Weldability: Unlike many superalloys, Inconel 718 is easy to weld and fabricate.
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Creep Resistance: Withstands long-term exposure to stress and high temperature.
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Durability: Provides long service life, reducing maintenance costs.
Applications of Inconel 718 Round Bar
Due to its unique properties, Inconel 718 round bar finds extensive applications in critical sectors:
1. Aerospace Industry
Inconel 718 is widely used in jet engines, turbines, and rocket motors due to its high strength-to-weight ratio and resistance to extreme heat. Components such as compressor blades, turbine discs, and engine casings rely on this alloy.
2. Oil and Gas Industry
The round bars are used in drilling equipment, downhole shafts, and valves, where resistance to corrosive seawater and hydrogen sulfide is crucial.
3. Power Generation
Gas turbines and nuclear reactors use Inconel 718 bars because of their ability to withstand high thermal stress and oxidation.
4. Marine Applications
Saltwater environments cause rapid corrosion to ordinary metals, but Inconel 718 bars resist pitting and crevice corrosion, making them suitable for shipbuilding and offshore platforms.
5. Chemical Processing
The alloy’s resistance to acids and alkalis makes it ideal for chemical plants, reactors, heat exchangers, and storage tanks.
6. Automotive and Racing Industry
High-performance engines and turbochargers use Inconel 718 round bars for durability and heat resistance.
Manufacturing Standards and Specifications
Inconel 718 round bars are manufactured as per various international standards to ensure quality and compatibility:
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ASTM B637 – Standard for precipitation-hardening nickel alloy bars, forgings, and forging stock.
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AMS 5662, AMS 5663, AMS 5664 – Aerospace specifications for Inconel 718.
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UNS N07718 – Unified Numbering System designation for Inconel 718.
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DIN 2.4668 – German designation.
Sizes vary from 3 mm to 300 mm in diameter, and they are available in various forms such as hot rolled, forged, or cold drawn.
Processing and Heat Treatment
Heat treatment is essential in enhancing the performance of Inconel 718 bar. The alloy undergoes solution annealing followed by precipitation hardening. This process improves strength while maintaining ductility and toughness. The controlled heat treatment also ensures stability under fluctuating thermal conditions.
Advantages of Using Inconel 718 Round Bar
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Extended Lifespan: Offers long-term performance in harsh conditions, reducing replacement frequency.
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Versatility: Suitable for aerospace, marine, energy, and industrial uses.
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Reliable Strength: Maintains mechanical integrity even under high pressure and temperature.
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Ease of Fabrication: Superior weldability compared to many nickel-based alloys.
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Cost-Effectiveness: While expensive initially, its durability lowers overall lifecycle costs.
How Inconel 718 Round Bar Compares to Other Alloys
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Vs. Stainless Steel: Stainless steel cannot match Inconel 718’s high-temperature strength and corrosion resistance.
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Vs. Inconel 625: Both alloys are corrosion-resistant, but Inconel 718 offers superior strength and creep resistance due to niobium hardening.
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Vs. Titanium Alloys: Titanium is lighter but lacks the same high-temperature strength as Inconel 718.
Future Demand for Inconel 718
With the rapid expansion of aerospace and energy sectors, the demand for Inconel alloy 718 round bars is expected to grow significantly. Its unique combination of properties positions it as a critical material for advanced engineering projects. The push for more efficient jet engines, renewable energy systems, and sustainable marine applications will further boost its usage.
Maintenance and Handling
Although Inconel 718 round bar is highly durable, proper handling ensures long-term performance:
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Store bars in a dry environment to avoid contamination.
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Use cutting tools with proper coatings, as the alloy is work-hardening in nature.
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Ensure proper lubrication during machining to maintain tool life.
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Apply recommended welding practices to avoid cracking.
Conclusion
Inconel 718 round bar is a high-performance material that combines strength, corrosion resistance, and heat stability. Its use across aerospace, oil and gas, marine, and power generation industries highlights its versatility and reliability. With excellent mechanical properties, ease of fabrication, and long service life, it continues to be a preferred choice for critical engineering applications worldwide.
Whether used in jet engines, turbines, or chemical plants, Inconel 718 bars deliver unmatched performance in extreme environments. As industries evolve, the role of Inconel 718 round bar will only grow, making it one of the most important materials in modern engineering.
