Inconel 625 vs Inconel 718: Detailed Comparison of Properties, Performance, and Applications

• Excellent corrosion resistance
• High strength without heat treatment
• Superb oxidation resistance
• Ideal for chemical, seawater, and high-temperature services

It is a solid-solution strengthened superalloy, meaning its strength comes from alloying elements, not heat treatment.

• Exceptional strength at high temperatures
• High creep resistance
• Superior fatigue and tensile performance
• Widely used in aerospace and turbine applications

Strength comes from Gamma Prime (γ′) and Gamma Double-Prime (γ″) precipitates after heat treatment.

• Nickel: 58% min
• Chromium: 20–23%
• Molybdenum: 8–10%
• Niobium + Tantalum: 3.15–4.15%
• Iron: 5% max

• Nickel: 50–55%
• Chromium: 17–21%
• Niobium: 4.75–5.5%
• Molybdenum: 2.8–3.3%
• Titanium & Aluminium (precipitation hardeners)

• Tensile Strength: ~690 MPa
• Yield Strength: ~310 MPa
• Hardness: ~95 HRB

• Tensile Strength: 1275 MPa
• Yield Strength: 1035 MPa
• Hardness: 36–44 HRC

Conclusion: 718 is nearly 2x stronger due to precipitation hardening.

• Inconel 625: Up to 980°C for oxidation resistance
• Excellent for chemical plants
• Maintains strength at elevated temperatures

• Inconel 718: Best below 650°C
• Strength decreases above 650°C (precipitate instability)
• Excellent creep resistance under 650°C

Conclusion:

• 625 is better for extremely high temperatures (800–1000°C)
• 718 is better for high-strength applications below 650°C

• Excellent resistance to seawater
• Strong resistance against chlorides
• Performs in acidic and alkaline media
• Resists oxidizing and reducing chemicals

• Good overall corrosion resistance
• Not as strong as 625 in aggressive media
• Used where corrosion + high strength are both required

• Inconel 625: Excellent weldability, no PWHT needed
• Ductile weld metal

• Inconel 718: Requires strict welding procedures
• Prone to cracking
• Needs post-weld heat treatment

• Seawater piping
• Heat exchangers
• Chemical processing vessels
• Aerospace exhaust systems
• Furnace hardware
• Desalination plants
• Offshore riser systems

• Jet engine components
• Turbine blades
• Rocket parts
• Downhole oilfield tools
• Fasteners
• High-temperature bolts
• Aerospace structural components

• Superior corrosion resistance required
• Exposure to seawater or chemicals
• Operating temperatures above 650°C
• Weldability is important
• Easy fabrication preferred

• Maximum strength needed
• Component faces extreme pressure
• Operating temperature below 650°C
• Aerospace or turbine application
• Fatigue resistance is critical