Ti-15V-3Cr-3Sn-3Al (Ti-15-3)
Introduction to Ti-15V-3Cr-3Sn-3Al (Ti-15-3)
Ti-15V-3Cr-3Sn-3Al, commonly referred to as Ti-15-3, is a metastable beta-titanium alloy developed for aerospace and high-performance industrial applications. It is known for its high strength-to-weight ratio, excellent cold formability, and outstanding toughness after heat treatment. Ti-15-3 is particularly suited for roll-forming, superplastic forming, and cold deep drawing in addition to precision CNC machining.
Due to its excellent machinability in the solution-treated condition, Ti-15-3 is an ideal choice for producing high-performance CNC machined titanium parts. These parts, manufactured through advanced CNC machining services, are often found in aerospace frames, engine supports, and precision components requiring high strength and fatigue resistance.
Chemical, Physical, and Mechanical Properties of Ti-15V-3Cr-3Sn-3Al (Ti-15-3)
Chemical Composition (Typical)
Element | Composition Range (wt.%) | Key Role |
|---|---|---|
Titanium (Ti) | Balance | Provides structural base and corrosion resistance |
Vanadium (V) | 14.0–16.0 | Beta stabilizer, enhances strength and hardenability |
Chromium (Cr) | 2.5–3.5 | Improves oxidation resistance and creep properties |
Tin (Sn) | 2.5–3.5 | Contributes to thermal stability and strength |
Aluminum (Al) | 2.5–3.5 | Enhances fatigue resistance and phase control |
Oxygen (O) | ≤0.13 | Increases strength; must be controlled for ductility |
Hydrogen (H) | ≤0.015 | Limited to avoid embrittlement |
Carbon (C) | ≤0.08 | Residual element |
Iron (Fe) | ≤0.30 | Residual element |
Physical Properties
Property | Value (Typical) | Test Standard/Condition |
|---|---|---|
Density | 4.66 g/cm³ | ASTM B311 |
Melting Range | 1590–1650°C | ASTM E1268 |
Thermal Conductivity | 6.6 W/m·K at 100°C | ASTM E1225 |
Electrical Resistivity | 1.68 µΩ·m at 20°C | ASTM B193 |
Thermal Expansion | 8.6 µm/m·°C | ASTM E228 |
Specific Heat Capacity | 550 J/kg·K at 20°C | ASTM E1269 |
Elastic Modulus | 105 GPa | ASTM E111 |
Mechanical Properties (Solution Treated + Aged)
Property | Value (Typical) | Test Standard |
|---|---|---|
Tensile Strength | 1000–1200 MPa | ASTM E8/E8M |
Yield Strength (0.2%) | 950–1150 MPa | ASTM E8/E8M |
Elongation | ≥8% | ASTM E8/E8M |
Hardness | 330–360 HB | ASTM E10 |
Fatigue Resistance | High | ASTM E466 |
Cold Formability | Excellent | ASTM F1162 |
Key Characteristics of Ti-15V-3Cr-3Sn-3Al (Ti-15-3)
High Strength and Lightweight: Ti-15-3 provides tensile strengths over 1000 MPa at nearly half the weight of steel, ideal for structural aerospace components.
Excellent Cold Workability: Unlike most titanium alloys, Ti-15-3 can be cold-formed into complex geometries without cracking, reducing fabrication steps.
Superior Fatigue Resistance: Maintains mechanical properties under cyclic loading, particularly useful for aircraft skin and bracket components.
Good Heat Treatability: Fully heat treatable to fine-tune strength, toughness, and fatigue life.
CNC Machining Challenges and Solutions for Ti-15-3 Titanium
Machining Challenges
Tool Wear: While more machinable than alpha or alpha-beta alloys, Ti-15-3 still causes abrasive wear on uncoated tools under dry or poor lubrication conditions.
Low Thermal Conductivity: Heat concentrates in the tool-workpiece interface, leading to premature tool degradation without high coolant pressure.
Elastic Recovery: With 105 GPa modulus, springback after cutting affects dimensional precision in tight-tolerance parts.
Work Hardening: Requires sharp tools and appropriate feeds to minimize hardening and surface roughness.
Optimized Machining Strategies
Tool Selection
Parameter | Recommendation | Rationale |
|---|---|---|
Tool Material | Carbide (K20/K30 grade) | Provides durability against wear and heat |
Coating | AlTiN or TiCN | Resists oxidation and galling |
Geometry | Positive rake, honed edge | Reduces stress concentration and burr formation |
Cutting Speed | 25–50 m/min | Balances heat and material removal |
Feed Rate | 0.10–0.25 mm/rev | Supports clean shearing with minimal vibration |
Coolant | Through-tool emulsion ≥100 bar | Ensures thermal management and tool life |
Ti-15V-3Cr-3Sn-3Al (Ti-15-3) 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 | 40–55 | 0.05–0.10 | 0.2–0.5 | 100–150 |
Surface Treatment for Ti-15-3 Titanium Parts
Hot Isostatic Pressing (HIP) enhances fatigue strength and removes internal voids, increasing structural integrity.
Heat Treatment involves solution treating at ~800°C followed by aging at 480–540°C for maximum strength and ductility.
Superalloy Welding enables reliable assembly with post-weld heat treatment to restore material properties.
Thermal Barrier Coating (TBC) offers protection in high-temperature cyclic environments, especially in aerospace systems.
CNC Machining supports ±0.01 mm tolerances for aircraft brackets, control linkages, and structural ribs.
Electrical Discharge Machining (EDM) provides precise micro-feature creation on aged or hard-machined components.
Deep Hole Drilling allows straight bores with Ra ≤1.6 µm and L/D >30:1 for aerospace and tooling applications.
Material Testing includes microstructure validation, hardness profiling, fatigue testing, and NDT per AMS standards.
Material Testing and Analysis
Ti-15-3 parts undergo fatigue testing, phase structure validation (via SEM/XRD), tensile testing post-aging, and ultrasonic NDT to verify material performance for flight-ready and high-load components.
Industry Applications of Ti-15V-3Cr-3Sn-3Al (Ti-15-3)
Aerospace: Aircraft frames, brackets, actuators, and formed skins benefiting from high fatigue resistance and cold formability.
Defense: Lightweight, high-strength structural members and missile casing components.
Industrial Equipment: Load-bearing arms and dynamic components in advanced automation.
Power Generation: Rotating structures and fittings exposed to thermal and vibrational fatigue.
FAQs
What makes Ti-15-3 ideal for cold forming and deep drawing in aerospace?
How does Ti-15-3 compare to Ti-6Al-4V in terms of machinability and fatigue performance?
What heat treatments optimize strength and ductility in Ti-15V-3Cr-3Sn-3Al components?
What CNC machining tolerances are achievable with Ti-15-3 for aerospace brackets?
Which industries benefit most from Ti-15-3’s cold formability and fatigue strength?
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