TA7 Alloy Composition

TA7 is a medium-strength, single-phase α-type titanium alloy with the nominal composition Ti-5Al-2.5Sn (5% aluminum, 2.5% tin). It exhibits excellent overall properties from cryogenic temperatures up to 500°C, including high specific strength, good plasticity, low notch sensitivity, and excellent weldability. Consequently, TA7 is widely used in aerospace for manufacturing structural components for low-temperature service, casings, panels, and fasteners.

A key characteristic of TA7 is its relatively narrow forging temperature window. Inadequate process control during hot working can easily lead to cracking. Furthermore, its microstructure and mechanical properties are highly sensitive to the forging temperature range and deformation, often resulting in defects like unqualified microstructure or substandard mechanical properties and a relatively low final yield rate.

With advancements in material preparation technologies, improved versions like TA7 ELI (Extra Low Interstitial) alloy have emerged. Advanced forming processes such as Selective Laser Melting (SLM) can further enhance material density and mechanical properties. Research shows that TA7 ELI alloy produced with optimized parameters can achieve a density of 99.89%, a tensile strength exceeding 1050 MPa, and an elongation of 15%.

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Chemical Composition Analysis
The chemical composition of TA7 alloy is strictly defined by the national standard GB/T 3620.1 "Designation and Chemical Composition of Titanium and Titanium Alloys".

Main Elements: Titanium (Ti) as the base, Aluminum (Al): 4.0-6.0%, Tin (Sn): 2.0-3.0%.

Key Impurity Limits (max): Iron (Fe) 0.30%, Silicon (Si) 0.15%, Carbon (C) 0.10%, Nitrogen (N) 0.05%, Hydrogen (H) 0.015%, Oxygen (O) 0.20%. Controlling interstitial elements (O, N, H) is crucial as they significantly affect plasticity and toughness. Requirements are even stricter for the TA7 ELI version.

Applicable Standards
The quality control and manufacturing of TA7 alloy materials follow a series of national standards.

GB/T 3620.1: Specifies the alloy designation and chemical composition limits.

GB/T 6612-1986: Specifically for TA7 alloy sheets, defining product conditions, specifications, and mechanical property requirements. Sheets are categorized by manufacturing method (hot-rolled, cold-rolled) and supply condition (e.g., hot-worked (R), annealed (M), cold-worked (Y)).

Room Temperature Mechanical Properties
TA7 exhibits a balanced combination of strength and plasticity at room temperature. According to GB/T 6612-1986, properties vary with sheet thickness.

For sheets 0.8-1.5 mm thick: Tensile strength (σb) ≥ 765 MPa, Yield strength (σ0.2) ≥ 685 MPa, Elongation (δ5) ≥ 20%.

For sheets 1.6-2.0 mm thick: Elongation ≥ 15%.

For sheets 2.1-10.0 mm thick: Elongation ≥ 12%.

Hardness Characteristics
While conventional TA7 hardness data is not directly provided, it is noted that TA7 ELI alloy formed by SLM exhibits high strength. The hardness of titanium alloys is generally influenced by microstructure, treatment condition, and test method. Hardness testing is often used as a quick, non-destructive method for quality control.

Mechanical Properties Under Special Processes
Advanced manufacturing processes can significantly enhance TA7's mechanical properties.

Selective Laser Melting (SLM): TA7 ELI alloy under optimized parameters (280 W laser power, 1000 mm/s scan speed) showed a tensile strength > 1050 MPa and 15% elongation in the as-deposited state.

Powder Metallurgy (P/M): TA7 ELI alloy prepared via P/M and Hot Isostatic Pressing (HIP: 1000°C, 130 MPa, 3 h) achieved a relative density up to 99.5% and a fine equiaxed grain structure (average grain diameter ~40 μm).

Density and Microstructural Characteristics

Density: Approximately 4.42 g/cm³. This low density contributes to its high specific strength (~172) and specific stiffness (~25,071).

Microstructure: A single-phase α-type alloy. This structure provides good microstructural stability and weldability but also results in relatively poorer plasticity and a narrow hot-working range.

Thermal Stability and Operational Temperature Range
TA7 maintains excellent mechanical properties from cryogenic temperatures up to 500°C. It shows good toughness at low temperatures and, as a single-phase α alloy, offers better creep resistance than α+β alloys at elevated temperatures.

Elastic Modulus: ~110,815 MPa

Poisson's Ratio: ~0.41

Main Application Areas

Aerospace Structural Components: Widely used for low-temperature structural parts, casings, panels, and fasteners in spacecraft and aero-engines (e.g., cryogenic propellant tanks, compressor casings).

Components Made by Special Processes: TA7 ELI alloy is suitable for manufacturing complex-shaped parts via SLM (e.g., lightweight brackets, custom medical implants) and Powder Metallurgy/HIP for near-net-shape parts.

Key Factors for Selection

Material State and Specification: Choose the appropriate manufacturing method (hot-rolled/cold-rolled) and supply condition (R, M, Y) based on the final application (further forming required vs. direct structural use).

Performance Balance: Balance strength, plasticity, toughness, and fatigue performance according to the component's criticality.

Process Suitability: Account for its narrow forging window. For complex parts, consider near-net-shape processes like additive manufacturing or powder metallurgy to reduce machining difficulty.

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Our factory operates a dedicated production facility equipped with modern machinery for processing titanium. We have a complete set of equipment including forging presses, hot and cold rolling mills, tube drawing and welding lines, bar & wire drawing machines, and surface treatment units. This allows us to control the production process from raw material to finished products such as sheets, plates, tubes, bars, and wires. Our workshop is capable of handling large-volume orders while maintaining consistent quality across our product range.

Our packaging is designed for maximum security and international standards. We use tailored wooden crates for heavy plates and bars, with internal waterproof wrapping and blocking to prevent movement. Tubes and coils are securely packed in wooden boxes with reinforced edges and protective end caps. For smaller items like wires and strips, we use standard export cartons with inner plastic and moisture-proof sealing. All packages are clearly marked with product details, weight, and handling instructions to ensure safe arrival. We can also customize packing methods, such as palletization or container optimization, based on specific shipping and customer requirements.

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