TA15 Titanium Alloy
TA15 is a typical near-α titanium alloy (α-type alloy with a small amount of β-stabilizing elements) developed in China, primarily designed for high-temperature structural applications. It combines excellent heat resistance, good weldability, and stable mechanical properties, making it widely used in aerospace and aviation fields. Below is a detailed overview:
1. Basic Information
Alloy Type: Near-α titanium alloy (main matrix is α phase, with a small volume fraction of β phase).
Core Characteristics:
Excellent high-temperature stability (long-term service temperature up to 500°C).
Good weldability and formability, suitable for manufacturing large integral structures.
Balanced strength and toughness, with stable performance at both room and elevated temperatures.
Lower density (≈4.5 g/cm³) compared to steel, offering significant lightweight advantages.
2. Chemical Composition (mass fraction, %)
TA15’s composition is optimized for heat resistance and processability, with key elements as follows:
Element Content Range Function
Titanium (Ti) Balance Matrix element
Aluminum (Al) 5.0 – 6.5% Strengthens the α phase, improves heat resistance and strength
Zirconium (Zr) 1.5 – 2.5% Enhances high-temperature creep resistance and refines grains
Molybdenum (Mo) 0.5 – 1.0% Introduces a small amount of β phase, improving toughness and weldability
Vanadium (V) 0.3 – 0.8% Stabilizes β phase, enhances processability
Iron (Fe) ≤0.30% Controlled impurity (excess reduces toughness)
3. Key Properties
(1) Mechanical Properties (typical values)
Tensile Strength (room temperature): 850 – 950 MPa.
Yield Strength (room temperature): 750 – 850 MPa.
Elongation: 10 – 15% (good plasticity, suitable for forming complex shapes).
Impact Toughness: ≥35 J/cm² (excellent fracture resistance).
Hardness (HRC): 30 – 35.
(2) High-Temperature Performance
Service Temperature: Long-term stable service at 450 – 500°C (higher than TC4’s 300°C, suitable for high-temperature components).
Creep Resistance: Low creep deformation under long-term high-temperature load (critical for engine or hot-end structural parts).
(3) Other Properties
Density: ~4.5 g/cm³ (lightweight advantage for aerospace).
Corrosion Resistance: Good in atmospheric, seawater, and most chemical environments (similar to pure titanium).
Weldability: Excellent weldability via TIG or electron beam welding, with welded joints retaining ~90% of base metal strength.
4. Heat Treatment
TA15’s properties can be adjusted through heat treatment, with common processes:
Annealing: Heat to 750 – 800°C, hold for 2 – 4 hours, then air cool. Improves plasticity and reduces internal stress (used for workpieces after forming or welding).
Solution + Aging: Less commonly used than annealing, as TA15 relies more on solid-solution strengthening from Al and Zr rather than heat treatment strengthening.
5. Processability
Forming: Good hot formability (e.g., forging, rolling) at 800 – 900°C; cold forming is possible but may require intermediate annealing to prevent cracking.
Machining: Moderate machinability, requiring sharp carbide tools and coolant to avoid high-temperature oxidation (which can embrittle the material).
Surface Treatment: Can be anodized, coated with heat-resistant layers, or shot-peened to improve fatigue resistance.
6. Applications
TA15 is widely used in high-temperature and structural components, especially in:
Aerospace: Aircraft fuselages, wing spars, engine casings, and high-temperature ducts (due to heat resistance and weldability for large integral structures).
Aero-Engines: Compressor disks, blades, and combustion chamber parts (withstanding 450 – 500°C operation).
Marine Engineering: High-strength, corrosion-resistant parts for submarines or offshore equipment.
7. Comparison with Similar Alloys
Property TA15 TC4 (Ti-6Al-4V) TA12 (Near-α)
Tensile Strength 850-950 MPa 900-1100 MPa 800-900 MPa
Service Temp 450-500°C 300°C 500-550°C
Weldability Excellent Good Good
Cost Medium Medium Higher
Note: TA15 balances heat resistance, strength, and weldability, making it ideal for medium-to-high temperature structural parts requiring integral welding.
Summary
TA15 is a high-performance near-α titanium alloy with excellent heat resistance, good weldability, and balanced mechanical properties. Its ability to withstand 450 – 500°C while maintaining strength and formability makes it a critical material in aerospace and aero-engine manufacturing, supporting the development of high-temperature, lightweight structural components.