1. Core Definition & Standard Compliance

1.1 Fundamental Overview

TC4 (Ti-6Al-4V) is an α-β titanium alloy—classified by its dual-phase microstructure (α-phase stabilized by aluminum, β-phase stabilized by vanadium)—that retains strength at elevated temperatures while maintaining ductility at cryogenic temperatures. Its naming and classification follow global conventions:

• Nomenclature Logic:

• "TC4": Chinese industrial designation ("T" = Titanium, "C" = Alloy, "4" = grade number, GB/T standard);

• "Ti-6Al-4V": Chemical composition-based name (6% aluminum, 4% vanadium);

• "ASTM Grade 5": Global commercial designation (the most specified titanium grade worldwide).

• Key Aliases: Ti6Al4V, Grade 5 Titanium, TC4 ELI (Extra Low Interstitial, medical-grade variant with reduced oxygen content).

• Equivalent Grades:

• ASTM: F136 (medical-grade), B265 (sheet/plate), B348 (bars);

• GB/T: TC4 (GB/T 3621), TC4 ELI (GB/T 3621);

• EN: 3.7165 (Ti-6Al-4V), 3.7164 (ELI variant);

• JIS: H4600 Ti-6Al-4V.

• Grade Variant: TC4 ELI (Extra Low Interstitial) – Oxygen content ≤0.13% (vs. ≤0.20% for standard TC4), enhanced ductility and biocompatibility for medical implants.

1.2 Core Standards

• Primary Standards: ASTM B265 (sheet/plate), ASTM F136 (medical ELI grade), GB/T 3621 (Chinese alloy standard), EN 10204 (European quality), JIS H4600 (Japanese);

• Quality Certifications: ISO 9001, ISO 13485 (medical), AS9100 (aerospace), NADCAP (aerospace manufacturing), and third-party certifications (SGS, BV, TÜV);

• Critical Requirements: Interstitial elements (O, N, C, H) strictly controlled—standard TC4: O ≤0.20%, N ≤0.05%, C ≤0.08%, H ≤0.015%; ELI grade: O ≤0.13%.

2. Chemical Composition & Alloy Design

TC4’s α-β dual-phase structure is engineered by precise aluminum and vanadium additions, delivering a balance of strength, ductility, and processability (mass fraction, %; per ASTM B265/GB/T 3621):

Core Alloy Advantage

The α-β dual-phase design is TC4’s defining strength:

• Aluminum stabilizes the α-phase (high strength, creep resistance) for elevated-temperature performance;

• Vanadium stabilizes the β-phase (ductility, toughness) for formability and weldability;

• Heat-treatable (annealing, solution aging) to tailor strength-ductility balance—outperforming pure titanium (TA1/TA2) by 2–3x in strength while retaining comparable corrosion resistance.

3. Mechanical & Physical Properties

TC4’s performance varies by heat treatment, with annealing (most common) and solution aging (for maximum strength) as key tempers. Below are typical values for 2–10mm thick sheet (ASTM B265 compliant):

3.1 Physical Properties

• Density: 4.43 g/cm³ (56% of steel, 2.7x denser than aluminum);

• Melting Point: 1649–1677°C (slightly lower than pure titanium due to alloy additions);

• Thermal Conductivity: 7.6 W/m·K (low—ideal for thermal insulation in aerospace);

• Electrical Conductivity: 2.3% IACS (poor conductor, suitable for electromagnetic shielding);

• Corrosion Resistance: Exceptional—resists seawater, chlorides, acids (HCl, H₂SO₄), and industrial chemicals; outperforms 304 stainless steel and aluminum in harsh environments;

• β-Transus Temperature: 980–1000°C (critical for heat treatment and hot working).

4. Production Process & Quality Control

TC4’s α-β structure requires precision manufacturing to optimize phase balance and minimize defects:

1. Raw Material Smelting:

• High-purity titanium sponge + aluminum-vanadium master alloy melted via Vacuum Arc Remelting (VAR, 2–3 melts) or Electron Beam (EB) melting to ensure uniform composition and low impurities;

• ELI grade uses ultra-low oxygen sponge and vacuum processing to control interstitial content.

2. Ingot Casting: Continuous casting into billets; homogenization annealing (920–950°C for 4–6 hours) to eliminate segregation and refine α-β phases.

3. Hot Working:

• Billets heated to 950–980°C (just below β-transus) for hot rolling/forging; ensures dual-phase microstructure and workability.

4. Cold Working: Precision cold rolling (3–5 passes) to target thickness (2–10mm); intermediate annealing (750–800°C) to relieve work hardening.

5. Heat Treatment (Temper Options):

• Annealing: 700–800°C for 1–2 hours (air cooling) – balances strength and ductility (most common for general use);

• Solution Aging: 920–950°C (solution) + water quenching + 500–550°C (aging for 4–8 hours) – maximizes strength for high-stress applications.

6. Surface Treatment:

• Pickling: HF-HNO₃ solution to remove oxide scale and α-case (brittle surface layer);

• Passivation: Forms a protective TiO₂ film to enhance corrosion resistance;

• Shot Peening: Improves fatigue life for aerospace components.

7. Quality Inspection:

• Ultrasonic Testing (UT, ASTM A609) for internal defects;

• Radiographic Testing (RT, ASTM E94) for critical aerospace/medical parts;

• Eddy Current Testing (ECT) for surface cracks;

• Chemical Testing: Spectrometric analysis (ASTM E1086) to verify alloy composition and interstitial content;

• Mechanical Testing: Tensile, bend, hardness, and fatigue tests (ASTM E466) for each batch;

• Non-Destructive Testing (NDT):

• Corrosion Testing: Salt spray (ASTM B117) and pitting corrosion (ASTM G48) tests;

• Microstructural Analysis: Optical microscopy to confirm α-β phase balance.

5. Core Applications

TC4’s unrivaled balance of strength, lightweight, corrosion resistance, and biocompatibility makes it the most versatile titanium alloy, spanning high-value industries:

5.1 Aerospace & Defense

• Aircraft structural components (wing spars, fuselage frames, landing gear parts);

• Jet engine components (blades, discs, casings) – retains strength at 300–400°C;

• Rocket/missile bodies and satellite structures – lightweight + high stiffness;

• Rationale: Strength-to-weight ratio 30% higher than steel; corrosion resistance to aviation fuels and harsh atmospheres.

5.2 Medical & Biomedical

• Orthopedic implants (hip/knee replacements, spinal fixation devices) – ELI grade;

• Dental implants and surgical instruments – biocompatibility (no tissue rejection);

• Cardiovascular devices (stents) – corrosion resistance in bodily fluids;

• Rationale: ELI grade’s low oxygen content + biocompatibility + fatigue resistance (matches human bone’s lifespan).

5.3 Advanced Manufacturing & 3D Printing

• Additive manufacturing (3D printing) – TC4 is the most widely used titanium powder for SLM/EBM processes;

• Custom components (aerospace prototypes, medical implants, tooling) – complex geometries without machining waste;

• Rationale: Excellent weldability and printability; retains high strength in as-printed or heat-treated states.

5.4 Marine & Offshore

• Ship propeller shafts, hull fittings, and offshore platform components;

• Deep-sea exploration equipment (submersible hulls) – resistance to seawater corrosion and pressure;

• Rationale: Outperforms stainless steel in saltwater (no pitting/corrosion after decades of use).

5.5 Automotive & Transportation

• High-performance automotive parts (exhaust systems, suspension components, racing engine parts);

• Electric vehicle (EV) battery enclosures and powertrain components – lightweight + crash resistance;

• Rationale: Reduces vehicle weight by 20–30% vs. steel, improving fuel efficiency/EV range.

5.6 Industrial & Chemical Processing

• Chemical reactor vessels, heat exchangers, and pipelines – resistance to corrosive acids/bases;

• Oil and gas downhole tools – withstands high pressure/temperature and sour gas (H₂S);

• Rationale: Durability in extreme industrial environments (no replacement for 20+ years).

6. Comparison with Similar Alloys

7. Cost & Pricing Considerations (2025 Q4 Data)

TC4’s premium performance and complex manufacturing result in a higher price than steel or aluminum, with variations by grade (standard vs. ELI) and form:

7.1 Key Pricing Drivers

• Alloy Complexity: Aluminum-vanadium master alloy accounts for 30–40% of cost;

• Manufacturing Process: VAR/EB melting adds 15–20% vs. pure titanium; 3D printing powder costs 50–80% more than sheet;

• Grade Variant: ELI grade commands 20–30% premium due to ultra-low oxygen control;

• Certification: Aerospace (AS9100) or medical (ISO 13485) certification adds 10–15%;

• Order Volume: Bulk orders (≥500kg) unlock 15–25% discounts vs. small orders (<50kg).

7.2 Cost Optimization Strategies

• Choose Standard TC4: Use non-ELI grade for industrial applications (saves 20–30% vs. ELI);

• Bulk Purchasing: Partner with manufacturers for annual supply agreements (locks in pricing);

• Optimize Form: Select sheet/plate over 3D printing powder for simple geometries (reduces cost by 50%);

• Domestic Sourcing: Chinese-manufactured TC4 offers 30–40% cost savings vs. Western suppliers with comparable quality.

8. Supply Chain & Value-Added Services

• Minimum Order Quantity (MOQ): 50kg (standard sheet); 10kg (ELI grade); 1kg (3D printing powder);

• Delivery Lead Time: 20–35 days (stock standard TC4); 35–50 days (ELI grade); 45–60 days (custom 3D printing powder);

• Packaging: Vacuum-sealed plastic + wooden crates (prevents oxygen absorption); medical/3D printing products double-packaged in sterile environments;

• Value-Added Services:

• Precision machining (CNC milling/turning);

• 3D printing powder customization (particle size 15–45μm);

• Heat treatment (solution aging for high strength);

• Certification support (AS9100, ISO 13485, NADCAP);

• Third-party testing (SGS/BV/TÜV) for critical applications;

• Global Supply Hubs: Core production bases in China (Baoji, Shanghai), USA (Pennsylvania, California), and Europe (Germany, UK); 3D printing powder hubs in Singapore and the Netherlands.

9. Conclusion

TC4 titanium alloy (Ti-6Al-4V) stands as the gold standard for high-performance materials, balancing exceptional strength-to-weight ratio, corrosion resistance, biocompatibility, and processability. Its α-β dual-phase design makes it adaptable to diverse heat treatments and manufacturing methods—from traditional rolling/forging to advanced 3D printing—enabling its dominance in aerospace, medical, marine, and industrial sectors.

While TC4 commands a premium over conventional materials, its long service life (20–50 years), low maintenance costs, and performance in extreme environments justify the investment for high-value applications. The standard grade excels in industrial and aerospace use, while the ELI variant is indispensable for medical implants. Backed by global standards, strict quality control, and a mature supply chain, TC4 remains the most versatile and widely adopted titanium alloy—trusted by engineers and buyers worldwide for its uncompromised reliability and performance.