Inconel 625 vs 718: Superalloy Comparison for CNC Machining

Inconel 625 excels in corrosion resistance and is solid-solution strengthened for weldability. Inconel 718 offers much higher strength through precipitation hardening and is the workhorse for jet engine and rocket components.

Side-by-Side Property Comparison

PropertyInconel 625Inconel 718
Tensile Strength827 MPa (120 ksi)1,241 MPa (180 ksi)
Yield Strength414 MPa (60 ksi)1,034 MPa (150 ksi)
Hardness175 HB36 HRC
Density8.44 g/cm³8.19 g/cm³
Machinability Rating12/10012/100
Thermal Conductivity9.8 W/m·K11.4 W/m·K
Melting Point1,290–1,350 °C1,260–1,336 °C
Tolerance±0.02 mm±0.02 mm

Key Differences

PropertyInconel 625Inconel 718Winner
Tensile Strength827 MPa1,241 MPaInconel
Max Service Temp982°C704°CInconel
Corrosion ResistanceSuperiorExcellentInconel
WeldabilityGoodModerateInconel
Machinability12/10012/100Tie
Age HardenableNoYesInconel

Which Material Should You Choose?

Choose Inconel 625 when:

  • Marine and chemical processing
  • Exhaust systems and ducting
  • Weldments and fabricated assemblies
  • Corrosion-critical applications
  • Lower-stress high-temperature parts
View Details Inconel 625

Choose Inconel 718 when:

  • Turbine disks and blades
  • Rocket engine components
  • High-strength high-temperature parts
  • Aerospace fasteners
  • Cryogenic applications
View Details Inconel 718

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