Titanium alloys for large aviation forgings

Titanium alloy has been widely used in the aviation industry due to its high specific strength, specific rigidity, corrosion resistance, and other excellent properties, and it has significant effects on the weight reduction of aircraft structures and the improvement of the service life of parts. Especially for military aircraft, some important structural components such as wing spars, bulkheads, landing gears, etc. are widely processed by titanium alloy forgings, which have high weight, large size, and cross-sectional area.

At present, the main grades of titanium alloys for aviation are TC4, TC18, TC21, TA15, TB6 (Ti 1023 Titanium Thick Plate in the United States), and so on. Among them, TC18 is suitable for manufacturing large forgings due to the highest hardenability and is currently the most widely used in China. Russia developed Ti-55531 titanium alloy on the basis of TC18 alloy based on the demand of civil aircrafts such as Boeing and Airbus by reducing the content of easily segregated element Fe. Ti-55531 has higher strength, superior hardenability, and a wider processing window. It has been used in parts such as A380 aircraft suspension joints and landing gear struts.

The domestic C919 aircraft has also carried out the research and development of domestic materials, and the domestic heavy-duty helicopters are also using this material to develop the central part of the large helicopter hub. The data collected so far show that: Compared with TC21 and TC18, Ti-55531 has higher tensile strength, lower plasticity and fracture toughness, higher fatigue limit, and is suitable for long-life design.