TA7 (Ti-5Al-2.5Sn) Alpha Titanium Alloy

TA7 is a Chinese α-type titanium alloy of nominal composition Ti-5Al-2.5Sn, corresponding directly to international Ti-5Al-2.5Sn / UNS R54520 / AMS 4924 (the low-interstitial ELI grade is used for cryogenic service). It offers relatively high strength, good weldability, good high-temperature performance up to about 500 °C and good corrosion resistance, and is widely used for aerospace engine cases and corrosion-resistant industrial equipment.

Overview

• Material: TA7 — Ti-5Al-2.5Sn α-type titanium alloy
• International equivalent: Ti-5Al-2.5Sn / UNS R54520 / AMS 4924
• Available forms: Bar, plate, sheet, tube, forgings and castings

Chemical Composition (wt%)

Other elements: each ≤ 0.10 %, total ≤ 0.40 %.

Physical Properties

Mechanical Properties

Key Features

• Relatively high strength capable of carrying substantial loads;
• Good corrosion resistance in a range of media;
• Low density supporting lightweight design;
• Good high-temperature properties, retaining strength and stability below about 500 °C;
• Good weldability for ease of fabrication.

Fabrication & Heat Treatment

• Melting: at least two vacuum arc remelts (VAR); Al and Sn are added as an Al-Sn master alloy; the consumable electrode is welded by argon-arc / plasma welding.
• Casting: graphite-machined, graphite-rammed, permanent-mould and investment-casting processes.
• Hot working: forge with a 1 h hold at about 1177 °C; working temperature not below 1010 °C; solution treatment after hot working.
• Cold working: cold rolled and cold drawn, with annealing after cold reduction.
• Welding: TIG and MIG welding under inert-gas shielding; good low-temperature toughness; brazing is rarely used; argon-arc, spot and seam welding are common. (Note: the source text contradicts itself on TIG during consumable-electrode preparation — normal TIG/MIG fabrication welding is fine.)
• Annealing: sheet 700–800 °C for 10–120 min, air cool; bar and forgings 750–850 °C for 0.5–4 h, air cool; castings 600–700 °C for 1–2 h, air or furnace cool.
• Stress-relief annealing: 540–650 °C for 15–360 min, air or furnace cool.
• HIP (castings): 100–140 MPa argon at 910 ±10 °C for 2–2.5 h, furnace cool to below 300 °C.

Typical Applications

• Aerospace: engine adapters, front-case shells, seal-holder housings, liners, brackets and panels;
• Chemical industry: vessels, piping and valves;
• Marine engineering: offshore-platform components and seawater-treatment equipment;
• Medical: artificial joints and bone-fixation devices.

Limitations

• Difficult to machine; hot working can pick up hydrogen, oxygen, nitrogen and carbon contamination;
• Relatively high production cost.

For detailed datasheets, mill certificates (EN 10204 3.1) or inquiries on specific sizes and tolerances, please contact our sales & engineering team.