Material Family

Titanium Alpha-Beta Alloy (Ti-6Al-4V)

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

Common Supply Conditions

1. Mill Annealed (MA): The standard condition offering a good balance of strength, ductility, and toughness. 2. Solution Treated & Aged (STA): For maximum strength, but with reduced ductility.

Most pipe is supplied and used in the Mill Annealed condition. STA is for specialized high-stress applications.

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

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

Mechanical Properties (Mill Annealed, Room Temp)

Tensile Strength (Rm): 895 - 1000 MPa
Yield Strength (Rp0.2): 828 - 930 MPa
Elongation (A): 10 - 15%
STA Condition (Typical): UTS ~1100-1200 MPa

Strength is approximately double that of CP Grade 2 pipe, 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.

Key Standards (Pipe)

Seamless Pipe: ASTM B861 / ASME SB-861 (Grade 5)
Welded Pipe: ASTM B862 / ASME SB-862 (Grade 5)
Aerospace: AMS 4945 (Seamless Tube)

ASTM B861/B862 are the primary commercial specs. AMS 4945 is a key aerospace procurement standard.

Common Sizes & Forms

OD Range: Typically from small tubing (1/8") to larger pipe (up to 12" NPS).
Wall Thickness: Light to heavy walls; often used as thin-walled tubing for hydraulic lines or heavy-walled pipe for structural components.
Forms: Both Seamless (SMLS) and Welded are available.

Seamless is preferred for high-pressure aerospace applications; welded can be used for large-diameter, low-pressure structural pipe.

Fittings & Fabrication

Compatible with ASTM B363 wrought fittings. Fair formability (hot forming preferred for complex shapes). Weldable using GTAW with strict argon shielding, but weld strength is typically lower than base metal.

Fabrication requires more expertise than with CP titanium grades. Post-weld heat treatment may be used for critical applications.

Typical Applications

• Aerospace: Aircraft hydraulic tubing, fuel lines, pneumatic systems, engine components, structural frames.
• Marine: High-stress submarine hull piping, propulsion shafts, heat exchanger tubing for high-pressure systems.
• Medical: Surgical implant components (e.g., trauma rods), instrument housings.
• Oil & Gas: Downhole instrumentation housings, high-pressure valve components.
• Racing & Automotive: High-performance hydraulic lines, exhaust systems, suspension components.

The dominant material for high-integrity, lightweight structural piping in advanced engineering sectors.