Inconel 625 and Inconel 718 are two of the most widely used nickel-based superalloys in demanding industries such as oil & gas, aerospace, power generation, and chemical processing. While both alloys offer excellent high-temperature performance and corrosion resistance, they are engineered for different primary purposes.

This article compares Inconel 625 vs Inconel 718 in terms of strength, corrosion resistance, temperature capability, fabrication, and cost, helping engineers and procurement teams determine which alloy is better for their specific application.

Overview of Inconel 625

Inconel 625 is a nickel-chromium-molybdenum alloy strengthened mainly by solid-solution strengthening, without the need for heat treatment.

Key Properties of Inconel 625

• Excellent resistance to corrosion and oxidation

• High strength across a wide temperature range

• Outstanding fatigue and thermal-fatigue resistance

• Very good weldability and formability

Typical Applications

• Offshore oil & gas structures

• Subsea pipelines and risers

• Heat exchangers

• Valves, fittings, and flanges

• Marine and seawater systems

Inconel 625 is widely chosen for environments where corrosion resistance and durability are critical.

Overview of Inconel 718

Inconel 718 is a precipitation-hardened nickel-chromium alloy designed for exceptionally high mechanical strength.

Key Properties of Inconel 718

• Extremely high tensile and yield strength

• Excellent creep and stress-rupture resistance

• Stable mechanical performance up to about 700°C (1290°F)

• Good fatigue resistance under high stress

Typical Applications

• Gas turbines and jet engines

• Oil & gas downhole tools

• High-pressure fasteners

• Aerospace structural components

• Nuclear and power generation equipment

Inconel 718 is ideal for applications requiring maximum strength and load-bearing capability.

Chemical Composition Comparison

Key Difference:

• Inconel 625 emphasizes corrosion resistance

• Inconel 718 emphasizes high mechanical strength

Strength and Mechanical Performance

Winner for strength: Inconel 718

Corrosion Resistance

• Inconel 625 provides superior resistance to seawater, chlorides, and general corrosion, making it highly suitable for offshore oil & gas environments.

• Inconel 718 offers good corrosion resistance but is not as corrosion-resistant as 625, especially in chloride-rich environments.

Winner for corrosion resistance: Inconel 625

Temperature Performance

• Inconel 625 maintains strength and corrosion resistance at elevated temperatures but is not precipitation-hardened.

• Inconel 718 retains exceptional mechanical strength up to 700°C, making it ideal for high-temperature, high-stress applications.

Winner for high-stress high-temperature environments: Inconel 718

Weldability and Fabrication

• Inconel 625 is easier to weld and fabricate, with minimal risk of cracking.

• Inconel 718 requires careful heat treatment and welding control due to its precipitation-hardening mechanism.

For complex structures and large pipes, Inconel 625 often offers lower fabrication risk.

Cost Considerations

• Inconel 718 is generally more expensive due to additional alloying elements and required heat treatment.

• Inconel 625 provides better cost-performance for corrosion-driven applications.

Which Is Better: Inconel 625 or Inconel 718?

Choose Inconel 625 if:

• Corrosion resistance is the primary concern

• The application involves seawater or offshore exposure

• Easy fabrication and welding are important

Choose Inconel 718 if:

• Extremely high strength and load-bearing capacity are required

• The application involves high pressure and high stress

• Dimensional stability under stress is critical

Conclusion

Neither Inconel 625 nor Inconel 718 is universally better—the best alloy depends on the application requirements.

• Inconel 625 excels in corrosion-resistant and marine environments

• Inconel 718 dominates in high-strength and high-stress applications

Understanding the key differences between Inconel 625 and Inconel 718 helps ensure optimal performance, safety, and cost efficiency in industrial projects.

Inconel 625 & 718 Bars, Rods, and Tubes Supplier

Ever Nickel Alloy manufacture and supply Inconel 625 and Inconel 718 bars, rods, pipes, and tubes for oil & gas, aerospace, and high-temperature industries.
Contact us for specifications, stock availability, and competitive pricing.