Application of titanium alloy in American fighter F22
F-22 fighter, a tactical fighter designed by the Lockheed Corporation, The Boeing Company and General Electric Company, is the representative fourth-generation fighter in the world. In combination of the stealth, the high mobility and the agility, and non-supersonic cruise, the F-22 fighter will serve as the main air force aircraft for the United States Air Force after 2000.
For the material selection, the main considerations are:
(1) The weight loss requirements brought by unconventional maneuver;
(2) Anti-continuous heating requirements caused by supersonic cruise;
(3) The main air-control aircraft led by stealth.
At the stage of engineering manufacturing and development, the proportion of titanium has increased to 41%.
F-22 mainly uses two kinds of titanium alloy: Ti-62222 (Ti-6AL-2Sn-2Zr-2Cr-2Mo) and Ti-6AL-4V, of which Ti-6AL-4V has alloy forged and cast products and Ti-6AL-4VELI alloy is used in the β annealing conditions. In addition, Ti-6AL-4V liquid pipe is also used; Ti-62222 has only the forging product. In the rear fuselage section of the F-22, the structural quality of titanium is 55%, mostly heat-resistant titanium alloy, in which Ti-6AL-4VELI Wyman is used. Engine compartment frame provided by Wyman·GordonCo, is monolithic Ti-6AL-4V forging, length of 3.8m, width of 7m, weight of 1590kg and projection area more than 5 square meters. The 30% complex medium fuselage section is titanium, having four forged titanium alloy integral bearing frame provided by Wyman·GordonCo, of which the largest weight is 2770kg, projection area is 5.5 square meters. Carbon accounts for 42% in the wing structure and the main wing beam is made by cutting titanium alloy forging. One of the innovations in the F-22 is to use the titanium alloy to manufacture complex parts of the main load-carrying structure, in adoption of hot-isostatic pressing technology that use a complex-shaped casting to replace multiple-piece assembly such as flaps, flaperon, rudder brake shell, connected wing on the body and lateral joints of the fuselage and inlet frame.
F-22 engine also uses a flame retardant titanium alloyC developed by the United States, which is used for high-pressure compressor receiver, afterburner cylinder and tail nozzle.