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Titanium (Ti-6Al-4V) vs Inconel 718: Complete Comparison

Compare Ti-6Al-4V (Grade 5) vs Inconel 718 for CNC machining. Mechanical properties, temperature resistance, cost, machinability, and application recommendations for aerospace and high-temperature components.

Ti-6Al-4V (Grade 5)vsInconel 718

Quick Answer

Choose Ti-6Al-4V for lightweight structural applications requiring high strength-to-weight ratio and corrosion resistance up to 400°C. Choose Inconel 718 for extreme-temperature applications up to 700°C where oxidation and creep resistance are critical. Ti-6Al-4V is lighter (4.43 vs 8.19 g/cm³) and easier to machine; Inconel 718 maintains strength at higher temperatures.

Quick Answer

Choose Ti-6Al-4V for lightweight structural applications (density 4.43 vs 8.19 g/cm³) with service temperatures up to 400°C. Choose Inconel 718 for extreme-temperature environments up to 700°C. Ti-6Al-4V is significantly easier to machine; Inconel 718 costs more and requires specialized tooling.

Side-by-Side Comparison

Property Ti-6Al-4V (Grade 5) Inconel 718
Density 4.43 g/cm³ 8.19 g/cm³
Ultimate Tensile Strength 950 MPa 1,275 MPa
Yield Strength (0.2%) 880 MPa 1,034 MPa
Max Service Temperature 400°C 700°C
Thermal Conductivity 6.7 W/m·K 11.4 W/m·K
Modulus of Elasticity 114 GPa 200 GPa
Hardness 36 HRC 40-44 HRC
Relative Machinability Moderate Difficult
Relative Cost $$ $$$$

Mechanical Properties

Ti-6Al-4V Advantages

  • 85% better strength-to-weight ratio (tensile/density)
  • Lower density (4.43 vs 8.19 g/cm³) — 46% lighter
  • Excellent corrosion resistance

Inconel 718 Advantages

  • 34% higher tensile strength (1,275 vs 950 MPa)
  • Service temperature to 700°C vs 400°C
  • Higher modulus (200 vs 114 GPa) — stiffer

Manufacturability

Aspect Ti-6Al-4V Inconel 718
Machinability Moderate Difficult to Very Difficult
Recommended Tooling Carbide (AlTiN coated) Ceramic or carbide (TiAlN coated)
Cutting Speed (milling) 40-90 m/min 20-40 m/min
Work Hardening Moderate Severe
Coolant Required (70+ bar) Required (high pressure)

Cost Analysis

Factor Ti-6Al-4V Inconel 718
Raw Material (per kg) $$ $$$$
Machining Time Baseline 2-3x longer
Tool Wear Moderate High (frequent tool changes)

Choose Ti-6Al-4V When

  • Weight reduction is critical (airframe structures, aerospace)
  • Service temperature is below 400°C
  • Corrosion resistance in seawater or chemical environments
  • Cost is a consideration

Choose Inconel 718 When

  • Operating temperature exceeds 400°C
  • Creep resistance is required at high temperatures
  • Extreme strength is needed at temperature
  • Highly corrosive + high-temperature environments

Selection Decision Framework

If temperature > 400°C → Inconel 718
If weight reduction critical → Ti-6Al-4V
If maximum strength at temperature → Inconel 718
If cost-sensitive → Ti-6Al-4V
If cryogenic application → Ti-6Al-4V
If creep resistance at 700°C → Inconel 718
  • Ti-6Al-4V: ASTM B265, ASTM B348, AMS 4928
  • Inconel 718: AMS 5662, AMS 5663, ASTM B637