Material Family

Titanium Alpha-Beta Alloy (Ti-6Al-4V, ELI variant available)

The workhorse high-strength titanium alloy, heat-treatable.

Common Designations

UNS R56400, Ti-6Al-4V, Grade 5, W.Nr. 3.7164/3.7165, TC4 (China)

The global standard for high-strength titanium components. "ELI" (Extra Low Interstitial) grade exists for high fracture toughness.

Key Characteristics

High Strength-to-Weight Ratio, Excellent Fatigue Strength, Good Corrosion Resistance.

The primary choice where strength, lightness, and durability are critical.

Chemical Composition (Typical wt.%)

Ti: Balance
Al: 5.5 - 6.75
V: 3.5 - 4.5
Fe: ≤ 0.40
O: ≤ 0.20
C: ≤ 0.08
N: ≤ 0.05
H: ≤ 0.015

Aluminum (Al) increases strength and stability. Vanadium (V) enhances hardenability and ductility.

Mechanical Properties (Annealed Plate, Room Temp - Typical)

Tensile Strength (Rm): 895 - 1000 MPa
Yield Strength (Rp0.2): 828 - 930 MPa
Elongation (A): 10 - 15%
Fatigue Strength: Very High

Strength is approximately double that of CP Grade 2, with a density of only 4.43 g/cm³.

Physical Properties

Density: 4.43 g/cm³
Melting Point: ~1650 °C
Elastic Modulus: 114 GPa
Service Temperature: Up to ~315°C (600°F) for long-term structural use.

Excellent specific strength (strength/density ratio), superior to many steels and aluminum alloys.

Key Corrosion Resistance

• Excellent resistance similar to CP titanium in oxidizing and chloride environments (seawater, chlorides, nitric acid).
• Immune to chloride stress corrosion cracking (Cl-SCC).• Good resistance to mild reducing acids when anodized or in presence of oxidants.

• ⚠️ Can be susceptible to crevice corrosion in hot (>70°C) brines; anodizing improves resistance.

Slightly less corrosion-resistant than pure grades in some media but still outstanding for most applications.

Heat Treatment

Not a precipitation-hardening alloy. Its primary condition is mill annealed. Can be solution treated and aged (STA) for higher strength (~1170 MPa UTS), but with reduced ductility and toughness.

Most plate is supplied and used in the annealed condition for optimal combination of properties.

Key Standards (Plate)

ASTM B265 / ASME SB-265 (Grade 5), AMS 4911 (Aerospace, most common), MIL-T-9046

AMS 4911 is the leading aerospace procurement specification for annealed sheet/plate.

Formability & Welding

Fair formability (hot forming preferred for complex shapes). Weldable using GTAW with proper technique and argon shielding, but weld strength is typically lower than base metal.

Fabrication requires more expertise than with CP titanium grades.

Typical Applications

• Aerospace: Airframe structural components, landing gear, engine mounts, fan blades, fasteners.
• Medical: Orthopedic implants (hips, knees, spinal), surgical tools (ELI grade used).
• Marine: High-stress submarine hulls, propulsion components, deep-sea pressure vessels.
• Automotive & Racing: Connecting rods, valves, springs for high-performance engines.
• Industrial: Turbine blades, high-pressure valves, and critical fatigue-resistant parts.

The dominant material for high-integrity structural applications across advanced engineering sectors.