Ti-3Al-2.5V (Grade 9) Titanium

Quick Answer

What is Ti-3Al-2.5V (Grade 9) titanium?
Grade 9 is an alpha-beta titanium alloy with approximately half the alloy content of Grade 5 (3% aluminium, 2.5% vanadium vs 6-4). It offers a middle-ground between the excellent formability of CP titanium grades and the high strength of Grade 5. Grade 9 is approximately 20% stronger than Grade 2 while being significantly more weldable and formable than Grade 5. It is the standard material for aerospace hydraulic and bleed-air tubing, and is widely used in marine, automotive, and sporting goods applications where a balance of strength, weight, and formability is needed.

Chemical Composition

Element	Weight %
Titanium (Ti)	balance
Aluminium (Al)	2.50–3.50
Vanadium (V)	2.00–3.00
Iron (Fe)	≤ 0.25
Oxygen (O)	≤ 0.15
Carbon (C)	≤ 0.08
Nitrogen (N)	≤ 0.03
Hydrogen (H)	≤ 0.015

Mechanical Properties

Property	Value
Density	4.48 g/cm³
Tensile Strength	620 MPa (min)
Yield Strength (0.2% offset)	515 MPa (min)
Elongation	15%
Hardness	30 HRC
Modulus of Elasticity	107 GPa
Max Service Temperature	350°C
Melting Point	1670°C

Machinability

Grade 9 machines more easily than Grade 5 due to its lower strength and reduced work-hardening tendency. It is comparable to annealed stainless steel in machinability. The alloy produces more manageable chips than Grade 5 and allows higher cutting speeds with acceptable tool life.

Recommended Cutting Parameters

Operation	Speed (SFM)	Feed (IPT)	DOC
Rough Milling	180–300	0.005–0.010	0.080–0.180
Finish Milling	250–400	0.003–0.006	0.010–0.050
Turning	250–400	0.006–0.014	0.050–0.150
Drilling	80–180	0.003–0.008	—

Key considerations:

• Carbide tooling recommended; coated carbide (AlTiN, TiAlN) improves tool life at higher speeds
• Standard coolant systems are adequate; high-pressure coolant prolongs tool life further
• Less prone to work hardening than Grade 5 — feed rates are less critical
• Excellent for tube machining (facing, chamfering, threading) — chip control still required
• Spring-back allowance needed for bending and forming operations

Typical Applications

• Aerospace: Hydraulic tubing (AMS 4945), bleed-air ducting, fuel lines, instrument lines, airframe structural tubing
• Marine: Seawater piping systems, hydraulic lines for subsea equipment, offshore platform instrumentation tubing
• Chemical Processing: Heat exchanger tubing, chemical transfer lines, pressure vessel internals
• Automotive: Exhaust components, roll cages, suspension springs, driveshafts
• Sporting Goods: Bicycle frames, golf club shafts, lacrosse stick shafts, tent poles
• Industrial: Heat exchanger tubing, condenser tubes, corrosion-resistant piping

Related Standards

• ASTM B265 — Titanium and Titanium Alloy Strip, Sheet, and Plate
• ASTM B348 — Titanium and Titanium Alloy Bars and Billets
• ASTM B861 — Titanium and Titanium Alloy Seamless Pipe (primary tube standard)
• AMS 4945 — Seamless Hydraulic Tubing (aerospace standard)
• ISO 5832-11 — Implants for Surgery — Ti-3Al-2.5V Alloy

Related Processes

• CNC Turning — Precision tube facing, chamfering, and threading for aerospace fittings
• CNC Milling — Clamp blocks, brackets, and fittings from bar or plate stock
• Welding — Excellent weldability; TIG welding with Grade 9 filler produces high-integrity joints
• Tube Bending & Hydroforming — Grade 9 has superior formability for complex bent-tube geometries
• Anodizing — Produces protective oxide; thinner coating than Grade 5 but sufficient for most environments
• Cold Forming — Suitable for swaging, flaring, and end-forming operations common in tube assemblies