Inconel 718 vs Ti-6Al-4V (Grade 5)
Inconel 718 and Ti-6Al-4V Grade 5 are both go-to alloys for demanding aerospace and high-performance hardware, but they answer different problems. Inconel 718 is a precipitation-hardened nickel superalloy built to hold strength in hot turbine sections, while Ti-6Al-4V trades absolute strength for an outstanding strength-to-weight ratio and near-immune corrosion resistance. Both are notoriously hard to machine and sit at the top of the cost scale.
The verdict
Choose Inconel 718 for hot-section components that must retain high strength above 400 C, where its ~700 C service temperature and 1375 MPa tensile dominate. Choose Ti-6Al-4V when weight matters most: at 4.43 g/cc it is roughly half the density of 718 (8.19 g/cc) with excellent corrosion resistance for airframe, marine, and medical use.
Side-by-side data
| Property | Inconel 718 | Ti-6Al-4V (Grade 5) |
|---|---|---|
| Category | Nickel Alloy | Titanium |
| Density (g/cm³) | 8.19 | 4.43 |
| Tensile strength (MPa) | 1375 | 1000 |
| Yield strength (MPa) | 1100 | 910 |
| Elongation (%) | 12 | 14 |
| Hardness | 42 HRC | 36 HRC |
| Max service temp (°C) | 700 | 400 |
| Machinability | ●●●●● | ●●●●● |
| Corrosion resistance | ●●●●● | ●●●●● |
| Relative cost | ●●●●● | ●●●●● |
| Thermal cond. (W/m·K) | 11.4 | 6.7 |
| Typically used for | High-strength hot turbine parts | Aerospace & medical — best strength-to-weight |
Which should you choose?
Choose Inconel 718 when…
- Parts run hot: 718 holds useful strength to ~700 C max service, well beyond Ti-6Al-4V's ~400 C ceiling
- You need the highest raw strength: 1375 MPa tensile / 1100 MPa yield vs Ti's 1000 / 910 MPa
- Building turbine discs, hot fasteners, exhaust and combustion hardware
- Creep and oxidation resistance at elevated temperature are gating requirements
- The application can tolerate the higher density (8.19 g/cc) in exchange for hot strength
- Cryogenic-to-hot cycling demands a single alloy with stable mechanical behavior
Choose Ti-6Al-4V Grade 5 when…
- Weight is the priority: 4.43 g/cc is roughly 46% lighter than Inconel 718
- You want the best strength-to-weight ratio for airframe, brackets, and structural parts
- Corrosion immunity is critical: Ti rates 5/5 vs 718's 4.5/5, including seawater and body fluids
- Designing medical implants or instruments needing biocompatibility
- Service stays at or below ~400 C, where Ti's temperature limit is not a constraint
- You can leverage Ti's lower density to cut fuel or inertial loads system-wide
Key differences that matter
- Density gap is decisive: Ti-6Al-4V (4.43 g/cc) is nearly half the mass of Inconel 718 (8.19 g/cc) for the same volume.
- Inconel 718 wins on absolute and hot strength: 1375 MPa tensile and a ~700 C service ceiling vs Ti's 1000 MPa and ~400 C.
- Ti-6Al-4V edges corrosion resistance (5/5 vs 4.5/5), the basis for its medical and marine use.
- Both rate at the bottom for machinability (718 at 1/5, Ti at 1.5/5) and demand rigid setups, sharp tooling, and slow feeds.
- Both sit at the maximum cost tier (5/5); neither is a budget choice and material plus machining drive part price.
- Thermal conductivity is low for both (718 ~11.4, Ti ~6.7 W/m-K), so machining heat concentrates at the cutting edge.
- On strength-to-weight, Ti leads at room temperature; on strength-at-temperature, 718 pulls decisively ahead.
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Open the Material SelectorGet a Quote →Frequently asked questions
Why is Inconel 718 chosen over titanium for turbine parts?
Titanium loses strength and oxidation resistance well before Inconel's limits. Inconel 718 retains high strength to roughly 700 C and resists creep and oxidation in hot gas paths, while Ti-6Al-4V is generally limited to about 400 C. For combustor and turbine hardware, that temperature margin is the deciding factor.
Which is lighter, Inconel 718 or Ti-6Al-4V?
Ti-6Al-4V is far lighter. Its density is 4.43 g/cc versus 8.19 g/cc for Inconel 718, so a titanium part weighs roughly 46% less than the same geometry in Inconel. That weight saving is the main reason titanium dominates airframe structure where temperatures stay moderate.
Are both alloys hard to machine?
Yes, both are among the most difficult metals to machine. Inconel 718 rates 1/5 and Ti-6Al-4V 1.5/5 in our data. Both work-harden, hold heat at the cutting edge due to low thermal conductivity, and require rigid fixturing, sharp carbide tooling, and conservative feeds and speeds.
Which costs more, Inconel 718 or Ti-6Al-4V?
Both sit at the top cost tier (5/5), so neither is inexpensive. Final part cost is usually driven more by machining difficulty, tool wear, and cycle time than by the raw stock. Treat both as premium choices justified only when their performance is genuinely required.
Property values are typical/nominal figures for early-stage guidance only and vary by temper, grade, supplier and heat treatment. Confirm critical specifications against a certified datasheet or with an mfgiq engineer before production.