Ti-6. 5Al-1Mo-1V-2Zr (TA15)

Ti-6.5Al-1Mo-1V-2Zr (TA15) is a near-alpha titanium alloy designed for CNC-machined aerospace and structural components requiring fatigue resistance, weldability, and thermal performance.

Introduction to Ti-6.5Al-1Mo-1V-2Zr (TA15)

Ti-6.5Al-1Mo-1V-2Zr, commonly known as TA15, is a high-strength alpha + beta titanium alloy widely used in aerospace, defense, and power engineering industries. It offers excellent weldability, high fatigue strength, and good creep resistance at elevated temperatures, making it ideal for structural components operating in demanding conditions.

TA15 exhibits a superior strength-to-weight ratio and stability under thermal loads. These attributes make it well-suited for critical CNC machined titanium parts, particularly when produced with high-precision CNC machining services that deliver tight tolerances and consistent quality for aerospace structures, engine mounts, and support frames.

Chemical, Physical, and Mechanical Properties of Ti-6.5Al-1Mo-1V-2Zr (TA15)

Chemical Composition (Typical)

Element	Composition Range (wt.%)	Key Role
Titanium (Ti)	Balance	Base element providing corrosion and structural strength
Aluminum (Al)	6.0–7.0	Alpha stabilizer that improves high-temperature strength
Molybdenum (Mo)	0.8–1.2	Beta stabilizer, enhances creep and fatigue resistance
Vanadium (V)	0.8–1.2	Increases strength and phase stability
Zirconium (Zr)	1.8–2.2	Promotes creep resistance and thermal stability
Oxygen (O)	≤0.15	Improves strength but affects ductility
Iron (Fe)	≤0.30	Residual element
Hydrogen (H)	≤0.015	Kept low to prevent embrittlement

Physical Properties

Property	Value (Typical)	Test Standard/Condition
Density	4.52 g/cm³	ASTM B311
Melting Range	1600–1650°C	ASTM E1268
Thermal Conductivity	7.0 W/m·K at 100°C	ASTM E1225
Electrical Resistivity	1.65 µΩ·m at 20°C	ASTM B193
Thermal Expansion	8.6 µm/m·°C	ASTM E228
Specific Heat Capacity	560 J/kg·K at 20°C	ASTM E1269
Elastic Modulus	115 GPa	ASTM E111

Mechanical Properties (Solution Treated + Aged)

Property	Value (Typical)	Test Standard
Tensile Strength	1000–1150 MPa	ASTM E8/E8M
Yield Strength (0.2%)	900–1050 MPa	ASTM E8/E8M
Elongation	≥8%	ASTM E8/E8M
Hardness	330–370 HB	ASTM E10
Creep Resistance	Excellent	ASTM E139
Fatigue Resistance	High	ASTM E466

Key Characteristics of Ti-6.5Al-1Mo-1V-2Zr (TA15)

High Structural Strength: With tensile strength >1000 MPa and fatigue strength suitable for aerospace-grade parts, TA15 is ideal for heavily loaded airframe structures.
Thermal and Oxidation Resistance: The alloy maintains structural integrity up to 500°C, resisting deformation and oxidation during prolonged service.
Good Weldability: TA15 can be welded using conventional methods with minimal impact on mechanical properties when followed by proper post-weld heat treatment.
Excellent Fatigue Life: Near-alpha microstructure supports long service in dynamic applications such as helicopter rotors and aircraft engine mounts.

CNC Machining Challenges and Solutions for TA15 Titanium

Machining Challenges

Low Thermal Conductivity: Like other titanium alloys, TA15 builds up heat at the tool–chip interface, increasing tool wear and thermal distortion.
Work Hardening and Elastic Recovery: This alloy rapidly works, hardens, and exhibits spring back due to its 115 GPa elastic modulus, affecting precision finishing.
Tool Adhesion: TA15 tends to adhere to cutting tools under insufficient cooling or poor tool geometry, leading to galling and surface damage.
Edge Notching and Chip Control: Continuous chip formation and notch wear require optimized cutting geometry and coolant strategy.

Optimized Machining Strategies

Tool Selection

Parameter	Recommendation	Rationale
Tool Material	Fine-grain carbide or PVD-coated inserts	Wear resistance and temperature stability
Coating	AlTiN or TiSiN (≥4 µm)	Prevents galling and improves tool longevity
Geometry	Positive rake, rounded edge	Reduces heat and cutting force
Cutting Speed	20–50 m/min	Controls thermal load
Feed Rate	0.10–0.25 mm/rev	Maintains chip thickness
Coolant	Emulsion coolant, ≥100 bar	Enhances cooling and chip evacuation

Ti-6.5Al-1Mo-1V-2Zr (TA15) Cutting Parameters (ISO 3685 Compliance)

Operation	Speed (m/min)	Feed (mm/rev)	Depth of Cut (mm)	Coolant Pressure (bar)
Roughing	20–30	0.15–0.20	2.0–3.0	80–100 (Through-tool)
Finishing	45–60	0.05–0.10	0.2–0.5	100–150

Surface Treatment for TA15 Titanium Parts

Hot Isostatic Pressing (HIP) enhances structural integrity and fatigue resistance, especially in airframe or turbine components.

Heat Treatment typically includes aging between 500–600°C to optimize phase distribution and creep resistance.

Superalloy Welding is effective with beta-compatible filler and post-weld stress relief to avoid alpha-case formation.

Thermal Barrier Coating (TBC) protects TA15 parts exposed to heat or oxidative environments, especially in exhaust systems.

CNC Machining supports the manufacture of structural components with tolerances as tight as ±0.01 mm.

Electrical Discharge Machining (EDM) enables micro-feature creation on hardened TA15 without thermal warping.

Deep Hole Drilling is ideal for precision bores and cooling channels, achieving Ra ≤ 1.6 µm and L/D > 30:1.

Material Testing includes mechanical, metallographic, creep, and non-destructive testing for QA in aerospace and defense.

Material Testing and Analysis

TA15 alloy components are validated through tensile and creep testing, fatigue analysis, phase microstructure evaluation (SEM/XRD), and ultrasonic or eddy current NDT based on AMS or GB standards.

Industry Applications of Ti-6.5Al-1Mo-1V-2Zr (TA15)

Aerospace: Ideal for structural airframe parts, engine pylons, and support beams requiring high fatigue resistance.
Defense: Used in missile components, rotor systems, and armored aerospace systems.
Power Generation: Applied in turbine disks, ducting, and pressure containment housings under thermal stress.
Industrial Equipment: Supports dynamic equipment exposed to cyclic stress and oxidation, such as heat exchanger housings.