When it comes to selecting high-performance alloy bars for demanding applications, especially in the oil & gas, aerospace, and marine industries, two materials often top the list: Inconel 925 bars and Inconel 718. Both are part of the Inconel family — renowned for their excellent corrosion resistance and mechanical strength under extreme conditions. But which one is right for your application?
In this guide, we compare Inconel 925 bars and Inconel 718 to help you make the best choice based on your project’s performance, corrosion, machining, and cost requirements.
What Are Inconel Alloys?
Inconel is a family of nickel-chromium-based superalloys known for their outstanding performance in high-temperature and corrosive environments. These alloys are widely used in aerospace, oil & gas, chemical processing, and marine industries. Each Inconel grade offers a unique set of properties, making it suitable for specific applications.
Overview of Inconel 925 Bars
Inconel 925 bars are nickel-iron-chromium alloys with added elements like molybdenum, copper, titanium, and aluminum. Designated as UNS N09925, this precipitation-hardenable alloy offers high strength, excellent corrosion resistance, and good fabricability.
Key Features of Inconel 925 Bars:
- High resistance to chloride stress-corrosion cracking
- Excellent performance in sour gas (H2S) environments
- Good strength and toughness after heat treatment
- Superior resistance to pitting and crevice corrosion
Due to these characteristics, Inconel 925 bars are often used in oil and gas extraction, particularly in components like tubing hangers, valves, and subsurface safety valves.
Overview of Inconel 718
Inconel 718, or UNS N07718, is another nickel-chromium alloy but with substantial additions of niobium, molybdenum, and titanium. It is known for its ability to maintain strength at temperatures up to 700°C (1300°F) and offers excellent fatigue, creep, and rupture resistance.
Key Features of Inconel 718:
- High tensile and yield strength
- Excellent weldability
- Good oxidation and corrosion resistance
- Outstanding performance in high-stress environments
Inconel 718 is widely used in aerospace, gas turbines, rocket motors, and power generation due to its superb high-temperature strength.
Chemical Composition Comparison
| Element | Inconel 925 (%) | Inconel 718 (%) |
| Nickel (Ni) | 42.0 – 46.0 | 50.0 – 55.0 |
| Chromium (Cr) | 19.5 – 22.5 | 17.0 – 21.0 |
| Iron (Fe) | Balance | Balance |
| Molybdenum (Mo) | 2.5 – 3.5 | 2.8 – 3.3 |
| Titanium (Ti) | 1.9 – 2.4 | 0.65 – 1.15 |
| Niobium (Nb) | — | 4.75 – 5.5 |
| Copper (Cu) | 1.5 – 3.0 | — |
| Aluminum (Al) | 0.1 – 0.5 | 0.2 – 0.8 |
Both alloys feature high nickel and chromium content for corrosion resistance, but Inconel 718 has more niobium and less copper, contributing to its superior high-temperature strength.
Mechanical Properties Comparison
| Property | Inconel 925 Bars | Inconel 718 |
| Tensile Strength | ~760 MPa (110 ksi) | 1240 MPa (180 ksi) |
| Yield Strength (0.2%) | ~517 MPa (75 ksi) | 1030 MPa (150 ksi) |
| Elongation | ~30% | 12–20% |
| Hardness (Rockwell C) | ~30 HRC | Up to 44 HRC |
| Max Service Temp | ~650°C (1200°F) | ~700°C (1300°F) |
Inconel 718 clearly outperforms Inconel 925 in terms of strength and hardness. However, Inconel 925 bars offer better ductility and are often sufficient for applications where extreme mechanical loads are not a concern.
Corrosion Resistance
Both alloys provide excellent corrosion resistance, but with slight differences:
- Inconel 925 Bars: Better suited for highly corrosive environments such as sour gas, chloride-laden, and acidic environments. It resists sulfide stress cracking and pitting due to the presence of copper and molybdenum.
- Inconel 718: Performs well in oxidizing environments but is not as resistant to certain chlorides as Inconel 925. Ideal for aerospace applications where oxidation at high temperatures is more critical than chloride resistance.
Applications Comparison
Inconel 925 Bars Are Commonly Used In:
- Oil and gas wellhead equipment
- Tubing and casing components
- Downhole tools
- Marine valves and fasteners
- Chemical processing systems
Inconel 718 Is Commonly Used In:
- Jet engines and turbine components
- Nuclear reactors
- Rocket motors and launch vehicles
- Automotive turbochargers
- Industrial gas turbines
The selection between Inconel 925 bars and Inconel 718 often comes down to the application’s mechanical stress and environmental conditions.
Fabrication and Machinability
- Inconel 925 Bars: Relatively easier to machine and weld compared to Inconel 718. Heat treatment enhances its mechanical properties without causing excessive hardening.
- Inconel 718: Known for poor machinability due to high strength and work-hardening properties. Requires specialized tools and machining techniques. However, it offers excellent weldability.
If ease of machining is a priority, Inconel 925 bars are the better option.
Cost Considerations
Due to its higher nickel and niobium content, Inconel 718 is generally more expensive than Inconel 925 bars. For applications that do not require the extreme high-temperature strength of 718, Inconel 925 offers a more cost-effective solution.
Summary: Which Alloy Should You Choose?
| Criteria | Best Choice |
| High-Temperature Strength | Inconel 718 |
| Sour Gas & Chloride Resistance | Inconel 925 Bars |
| Machinability & Fabrication | Inconel 925 Bars |
| Aerospace & Jet Engines | Inconel 718 |
| Oil & Gas Applications | Inconel 925 Bars |
| Budget-Conscious Projects | Inconel 925 Bars |
Conclusion
Both Inconel 925 bars and Inconel 718 offer exceptional performance, but they are optimized for different conditions. If your project demands high strength at elevated temperatures — such as in aerospace turbines or nuclear applications — Inconel 718 is the ideal candidate. On the other hand, for corrosive environments like offshore drilling or chemical processing, Inconel 925 bars provide an excellent blend of strength, corrosion resistance, and affordability.
Choosing the right alloy is critical to ensuring the longevity, safety, and efficiency of your systems. Always consider environmental conditions, mechanical stress, fabrication methods, and cost before making your selection.
Need help sourcing high-quality Inconel 925 bars? Get in touch with trusted suppliers to ensure certified material and prompt delivery for your industrial needs.
