Titanium alloy has high strength, low density, good mechanical properties, toughness and corrosion resistance. In addition, titanium alloys have poor process performance and are difficult to cut. In hot processing, it is very easy to absorb impurities such as hydrogen, oxygen, nitrogen, and carbon. There is also poor abrasion resistance and complex production processes. Industrial production of titanium began in 1948. The development of the aviation industry requires the titanium industry to develop at an average annual growth rate of about 8%. The world's annual output of titanium alloy processing materials has reached more than 40,000 tons, with nearly 30 titanium alloy grades. The most widely used titanium alloys are Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (TA7) and industrial pure titanium (TA1, TA2 and TA3).
Titanium alloy is mainly used for the production of aircraft engine compressor components, followed by the structural parts of rockets, missiles and high-speed aircraft. In the mid-1960s, titanium and its alloys have been used in general industry to make electrodes in the electrolysis industry, condensers in power stations, heaters for petroleum refining and seawater desalination, and environmental pollution control devices. Titanium and its alloys have become a kind of corrosion-resistant structural materials. In addition, it is also used to produce hydrogen storage materials and shape memory alloys.
China began research on titanium and titanium alloys in 1956; in the mid-1960s, industrialized production of titanium materials began and developed into TB2 alloys.
Titanium alloy is a new important structural material used in the aerospace industry. Its specific gravity, strength and service temperature are between aluminum and steel, but it is stronger than aluminum and steel and has excellent seawater corrosion resistance and ultra-low temperature performance. In 1950, the United States used it for the first time on the F-84 fighter bomber as non-load bearing components such as rear fuselage heat shields, wind deflectors, and tail covers. Since the 1960s, the use of titanium alloy moved from the rear fuselage to the middle fuselage, partially replacing structural steel to make important load-bearing components such as bulkheads, beams, and flap slides. The amount of titanium alloy used in military aircraft has increased rapidly, reaching 20% to 25% of the weight of the aircraft structure. Since the 1970s, civilian aircraft began to use titanium alloys in large quantities. For example, Boeing 747 passenger aircraft used more than 3,640 kilograms of titanium. Aircraft with a Mach number greater than 2.5 use titanium to replace steel to reduce structural weight. For another example, the US SR-71 high-altitude and high-speed reconnaissance aircraft (flying Mach number 3, flying height 26212 meters), titanium accounts for 93% of the weight of the aircraft structure, so-called "all-titanium" aircraft. When the thrust-to-weight ratio of the aero engine increases from 4-6 to 8-10, and the compressor outlet temperature increases from 200-300°C to 500-600°C, the original low-pressure compressor discs and blades made of aluminum must Use titanium alloy instead, or use titanium alloy instead of stainless steel to make high-pressure compressor discs and blades to reduce structural weight. In the 1970s, the amount of titanium alloy used in aero engines generally accounted for 20% to 30% of the total weight of the structure. It was mainly used to manufacture compressor components, such as forged titanium fans, compressor discs and blades, cast titanium compressor casings, and intermediaries. Case, bearing housing, etc. The spacecraft mainly uses the high specific strength, corrosion resistance and low temperature resistance of titanium alloys to manufacture various pressure vessels, fuel tanks, fasteners, instrument straps, structures and rocket shells. Artificial earth satellites, lunar modules, manned spacecraft and space shuttles also use titanium alloy sheet welded parts.