Beta 21S (Ti-15Mo-3Al-2.7Nb-0.2Si) is a metastable β-type titanium alloy, renowned for its excellent oxidation resistance and outstanding cold-working capabilities. Its production, performance, and applications in sheet form are summarized below.
The production and processing of Beta 21S sheets possess the following key characteristics: Excellent cold-working performance is one of its core advantages. This alloy exhibits good room-temperature plasticity in the solution-treated state, making it ideal for cold rolling, cold bending, and other forming operations. It can produce foils with a thickness of 0.064 mm, and the total cold-rolling deformation can reach 72%~85% without intermediate annealing. This makes it easy to manufacture complex aircraft sheet metal parts. Key Points of Cold Rolling Process: To obtain the ideal fine-grained structure in subsequent heat treatment, the cold-rolling deformation needs to be controlled within a certain range. Studies have shown that a deformation of more than 55% is required to obtain a fine-grained structure below 30 μm after subsequent solution treatment (e.g., 845℃/10min). Weldability: This alloy can be joined using any welding method suitable for titanium alloys.
Aging temperature is key to property control: lower aging temperatures result in higher strength and lower plasticity; conversely, higher aging temperatures decrease strength and improve plasticity. For example, after 50% cold rolling deformation and aging, the strength can reach up to 1770 MPa, while optimized heat treatment can stably achieve ultra-high strengths above 1300 MPa, while maintaining elongation above 10%.
Beta 21S's oxidation resistance is a hallmark feature. After exposure to 815°C for 48 hours, its oxidation rate is only 1% of that of another β-titanium alloy, Ti-15-3. This allows it to maintain excellent thermal stability and creep resistance within a temperature range of 500°C to 590°C.
Due to its comprehensive performance advantages, Beta 21S sheets are primarily used in the aerospace field: aircraft engine components: used to manufacture nacelle components and wind deflectors for Boeing 777 aircraft engines, utilizing its high strength and heat resistance. Airframe structural components: Suitable for aircraft structural components, honeycomb structures, fasteners, and hydraulic lines with temperature requirements. Aerospace hot-end structures: Originally developed as an antioxidant matrix for metal matrix composites (MMC) in the National Aeronautics and Space Program (NASP), it can be used in high-temperature components of the Space Shuttle.
Beta21S (Ti-15Mo-3Nb-3Al-0.2Si) metastable β-titanium alloy sheet possesses excellent cold-forming capabilities. In the solution-treated state, it can achieve large deformation stamping and bending. After aging treatment, it achieves ultra-high strength. Its long-term service temperature can reach 540℃. It exhibits excellent high-temperature oxidation and creep resistance and is resistant to corrosion from aerospace Skydrol hydraulic media. It is widely used in aero-engine exhaust nozzle components, thrust reversers, cabin thermal insulation thin walls, and hydraulic system components. It can also be rolled into ultra-thin foil as a matrix for silicon carbide fiber-reinforced titanium matrix composites, making it a core material for high-end lightweight high-temperature structures in aerospace.
