Inconel (Nickel Superalloy) (Ni+Cr+Fe)
Inconel is a family of nickel-chromium superalloys designed for extreme temperatures and corrosive environments where conventional stainless steels fail. Maintaining exceptional strength at 700–1,100°C, these alloys are the backbone of jet engines, gas turbines, nuclear reactors, and chemical processing equipment.
Properties
- Density
- 8,190–8,440 kg/m³
- Melting Point
- 1,260–1,390 °C
- Boiling Point
- ~2,700 °C
- Thermal Conductivity
- 9.8–14.8 W/(m·K)
- Electrical Resistivity
- 1.03–1.30 × 10⁻⁶ Ω·m
- Tensile Strength
- 690–1,400 MPa
- Yield Strength
- 280–1,200 MPa
- Hardness
- 150–425 HB
- Elongation
- 12–50%
- Crystal Structure
- FCC (γ-matrix)
Common Grades
- Inconel 625 (2.4856): Solid-solution strengthened. Outstanding corrosion resistance and fatigue strength. Marine, chemical, aerospace.
- Inconel 718 (2.4668): Precipitation-hardened workhorse. 65% of all superalloy production. Jet engine discs, shafts, fasteners.
- Inconel 600 (2.4816): Basic Ni-Cr-Fe alloy. Nuclear reactors, chemical processing, high-temperature furnace components.
- Inconel X-750 (2.4669): Precipitation-hardened for springs and fasteners at elevated temperatures. Gas turbine blades.
Applications
- Aerospace: Turbine discs, combustion chambers, exhaust systems, afterburner components, turbopump shafts
- Power Generation: Gas turbine hot sections, nuclear reactor cores, steam generators, heat recovery systems
- Oil & Gas: Downhole tools, wellhead components, subsea connectors, sour gas service equipment
- Chemical Processing: Reactors handling fluorine, chlorine, and strong acids at elevated temperatures
FAQ
What is the difference between Inconel 625 and 718?
625 is solid-solution strengthened (annealed, no aging needed), offers the best corrosion resistance, and is preferred for chemical and marine applications. 718 is precipitation-hardened (aged to develop γ'' strengthening), achieving much higher yield strength (1,034 MPa vs. 490 MPa) and is the dominant aerospace alloy for structural components.
Why can't stainless steel replace Inconel?
At temperatures above 600°C, stainless steels lose significant strength and suffer accelerated oxidation and creep. Inconel maintains useful strength to 1,000°C+ thanks to its nickel-rich FCC matrix and precipitation hardening. The Ni-Cr oxide layer is also more stable than Cr₂O₃ alone at extreme temperatures.
Can Inconel be 3D printed?
Yes — Inconel 625 and 718 are among the most successfully 3D-printed metal alloys. Laser Powder Bed Fusion (LPBF) produces parts with 99.5%+ density and mechanical properties meeting AMS specifications after heat treatment. This enables complex cooling channels in turbine blades and reduces manufacturing lead times from months to days.