Application of Titanium Materials in Large Passenger Aircraft
The A3XX passenger aircraft of Air Bus of Europe, the B77X aircraft of Boeing of the United States, the C919 of COMAC, and the CR929 aircraft produced by the Sino-Russian joint venture are all made of titanium materials. Structure.
The development of the C919 large passenger aircraft completely independently developed by China began in 2008. On November 2, 2015, the first prototype was rolled off the production line and tested at Shanghai Commercial Aircraft Co., Ltd. The first flight in May 2017 was carried out in November. After the first transfer flight, the second C919 large aircraft made its maiden flight at Shanghai Pudong Airport in December, marking that the domestic large aircraft has entered a new stage of comprehensive test flight. Although the materials used in the prototype are all foreign goods, they are mainly for the needs of obtaining airworthiness certificates. Since the second aircraft, the amount of domestic materials has been increasing batch by batch, year by year.
Titanium has been widely used in the manufacture of large civil aircraft. Some key parts of landing gear and wheels are forged with titanium alloy, and a small number of parts are forged with aluminum alloy. In the C919 large aircraft, the net mass of titanium alloy parts accounts for about 10% of the total net mass of the aircraft. Among the civil aircraft manufactured in China, the amount of titanium is the largest. Which parts are made of titanium: the nose, which uses Ti-6Al-4V ELI titanium forging; for suspension, Ti-6Al-4V alloy forgings, sheets and titanium alloy 55531 forgings are used; Ti-6Al-4V alloy forgings are used for tail wings; Ti-6Al- 4V alloy forgings and plates; Ti-6Al-4V ELI titanium forging for the center wing; Ti-6Al-4V alloy forging for the landing gear system.
Ti-6Al-4V (TC4, GB/T3620) is a medium-strength (>900MPa) α+β-type alloy, which was developed by the US Watertown (also translated as Watertown) Arsenal in 1954 and is widely used in aviation In the aerospace field, the output of semi-finished products accounts for 55%-65% of the world's total titanium production, which is used to produce various aerospace forgings and plates. Because of its excellent comprehensive performance, moderate price and early forming, it is the most studied. In-depth, used for the longest time, and the application field is the most extensive, so the alloy has maintained strong vitality since its birth 67 years ago. The grade of this alloy is TC4 in China, Ti-6Al-4V from American Titanium Company (Timet), RMI 6Al4V from American Active Metals Company, IMI318 from British Titanium Metal, BT6 from Russia and BT6 from Sumitomo Metals from Japan. ST-AI40, TA6V of France, LT31 of Krupp of Germany. TC4 alloy is applied in the annealed state and can be strengthened by heat treatment, but the weldability is poor. "ELI" in Ti-6Al-4V ELI means Extro-Low Interstitial titanium alloys are α and α+β titanium alloys suitable for use at low temperatures, their strength properties increase with decreasing temperature, Toughness decreases very little with temperature and can be used to make low temperature structural parts. The oxygen content of low-temperature titanium alloys is very low, from ordinary grade 0.2% oxygen to ≤0.12%, and can be used at extremely low temperatures (<77K). Typical alloys are Ti-5Al-2.5Sn (ELI) and Ti- 6AI-4V (ELI). Ti-5Al-2.5Sn ELI is an American alloy, which was introduced in the early 1960s and was successfully copied in China in the late 1970s. The grade is TA7 (Chinese military standard GJ B495). Ti-5Al-2.5Sn ELI alloys are particularly suitable for liquid fuel storage tanks operating at -255°C. These two titanium alloys are available in sufficient supply from China Baotai Group.
The A380 large passenger plane of European Airbus is the largest wide-body civil aircraft in the world, and it also consumes the most titanium materials. The net mass of titanium alloy parts accounts for about 10% of the total net mass of the whole aircraft, and the consumption of titanium materials for a single aircraft is about 65 tons. . The parts made of titanium alloy are mainly (see Figure 2): the pod, skin, attachment port of the engine, connecting ring wings, front bulkhead, shaft and wing between inner flaps, hinged track raceway , 3 stiffeners on the trailing edge, shaft parts and hinges, part of the engine hanger, propulsion parts, leading edge, front bracket, part of the landing gear, and the wing (strip) rail can be welded.
