Ti-6Al-4V (Grade 5) Titanium

Quick Answer

What is Ti-6Al-4V (Grade 5) titanium?
Ti-6Al-4V is an alpha-beta titanium alloy containing 6% aluminium and 4% vanadium. It is the most commonly specified titanium alloy, accounting for approximately 50% of global titanium consumption. Grade 5 offers an outstanding strength-to-weight ratio, excellent corrosion resistance, and proven biocompatibility, making it the default choice for aerospace structures, medical implants, and high-performance industrial components.

Chemical Composition

Element	Weight %
Titanium (Ti)	balance
Aluminium (Al)	5.50–6.75
Vanadium (V)	3.50–4.50
Iron (Fe)	≤ 0.40
Oxygen (O)	≤ 0.20
Carbon (C)	≤ 0.08
Nitrogen (N)	≤ 0.05
Hydrogen (H)	≤ 0.015

Mechanical Properties

Property	Value
Density	4.43 g/cm³
Tensile Strength	950 MPa (min)
Yield Strength (0.2% offset)	880 MPa (min)
Elongation	14%
Reduction of Area	36%
Hardness	36 HRC
Modulus of Elasticity	114 GPa
Max Service Temperature	400°C
Melting Point	1660°C
Fatigue Strength (10⁷ cycles)	510 MPa

Machinability

Grade 5 titanium is more challenging to machine than aluminium or steel due to its low thermal conductivity (7 W/m·K), high chemical reactivity, and work-hardening characteristics. Successful machining requires rigid setups, sharp carbide tooling, and generous coolant application.

Recommended Cutting Parameters

Operation	Speed (SFM)	Feed (IPT)	DOC
Rough Milling	150–250	0.004–0.008	0.100–0.200
Finish Milling	200–300	0.003–0.005	0.010–0.050
Turning	200–350	0.005–0.012	0.050–0.150
Drilling	50–120	0.002–0.006	—
Tapping	20–40	—	—

Key considerations:

• Use micro-grain carbide or PCD tooling with honed edges
• High-pressure coolant (1000+ PSI) directed at the cutting zone is critical
• Climb milling preferred to reduce work hardening
• Rigid fixturing with minimal overhang; titanium spring-back requires compensation
• Peel milling and trochoidal toolpaths improve tool life in deep cavities
• Avoid dwell or rubbing — feed must be maintained to prevent work hardening

Typical Applications

• Aerospace: Airframe structural components, landing gear, engine brackets, fan blades, fasteners
• Medical: Orthopaedic implants (hips, knees, trauma plates), surgical instruments, dental implants
• Semiconductor: Vacuum chamber components, wafer handling end-effectors, chamber liners
• Automotive: Connecting rods, valves, exhaust systems, springs
• Marine: Propeller shafts, seawater piping, underwater connectors
• Energy: Oil and gas downhole tooling, geothermal components, subsea hardware
• Defence: Armour plating, missile components, structural aircraft parts

Related Standards

• ASTM B265 — Titanium and Titanium Alloy Strip, Sheet, and Plate
• ASTM B348 — Titanium and Titanium Alloy Bars and Billets
• ASTM F136 — Wrought Ti-6Al-4V ELI for Medical Implants (surgical implant grade)
• AMS 4911 — Titanium Alloy Sheet, Strip, and Plate (aerospace)
• AMS 4928 — Titanium Alloy Bars, Wire, Forgings, and Rings (aerospace)
• ISO 5832-3 — Implants for Surgery — Ti-6Al-4V Wrought Alloy

Related Processes

• 5-Axis CNC Machining — Complex aerospace and medical geometries from solid billet
• CNC Milling & Turning — Standard precision machining with dedicated titanium toolpaths
• Wire EDM — Suitable for Grade 5; slower than steel but produces excellent surface finish
• Additive Manufacturing (DMLS) — Grade 5 is the most common titanium alloy for powder-bed fusion
• Welding — TIG and laser weldable; requires inert gas shielding and stress relief
• Heat Treatment — Solution treatment and aging (STA) can increase strength to 1170 MPa