Application of Titanium on American Spacecraft

Titanium has been widely used in spacecraft since the United States. The development of the Mercury spacecraft began in 1972, and it was first launched in 1981 to put man into space. The mass of the ship is 2t, which is divided into three parts: base, airtight compartment and top. The pressure chamber has a volume of 1.4 m³, and the main structure is made of titanium alloy, which accounts for 80% of the total structure mass and weighs 168 kg. The amount of titanium used is about 240kg. Sealed compartments can accommodate astronauts. It has moderate mechanical strength, and some of the frame rings are made of Ti-6Al-4V alloy. Ti-6Al-4V is one of the popular titanium alloys. It is a well-integrated alloy. It not only has high mechanical properties, but also can be used for a long time at 480 C. It has high heat resistance, good weldability, excellent airtightness of the weld, and is very advantageous to adjust the pressure in cabin.

The Gemini spaceship was launched in 1984 and is an improvement of the Mercury spaceship. However, there are more titanium alloys and varieties available, sharing 7 types. The net mass of the titanium structures is about 570 kg, accounting for 84% of the net mass of the structures. The ship's inner wall is double-layered, welded with 0.25mm thick industrial pure titanium plates. The spacecraft must slow down when it returns to the atmosphere, a task performed by four round rockets loaded with solid fuel, each with two Ti-6Al-4V welded titanium alloy semispheres 1.0mm thick.

Apollo spacecraft is similar to Chang E-5, a lunar exploration project launched by the Chinese Space Administration in 2020. But Chang E-5 was not manned, while Apollo put a man on the moon, landed on the surface of the moon, and then returned to the earth. It consists of a ship hull and a large Saturn-V rocket, with a mass of 50t and a mass of 2900t. The ship contains a 7.65m³ command module, a mechanical module and a lunar landing module. The spacecraft and rocket structures share a total of 68 t of titanium. All brackets, fixtures and fasteners of the ship are titanium. The command cabin, mechanical cabin and landing module share 1190 kg of titanium.

The tower structure of the launch traction system is made of titanium alloy, and the liquid hydrogen containers and the cryogenic containers of the command and mechanical cabins and the lunar module are made of Ti-6Al-4V alloy. The lower portion of the lunar module requires greater plasticity and is therefore made of Ti-5Al-2.5Sn alloy. The Apollo spacecraft has more than 40 pressure vessels, of which about 85% are made of titanium alloy. Nitrogen tetroxide, helium, nitrogen and fuel containers are made of Ti-6Al-4V and Ti-5Al-2.5Sn alloy. The Ti-5Al-2.5Sn alloy is used for liquid hydrogen and supercritical helium containers because of its high ductility at -252.7 C.

The space shuttle is a means of communication between the ground and the space station, so it is also called a space ferry, which requires multiple uses, preferably up to 100 or more times. When it enters the atmosphere, the upper surface temperature of its body and wing can range from 180 to 815 degrees C. Therefore, components in some parts need to be made of heat-resistant titanium alloy, such as Ti/B-Al composite material for the upper body frame, tail wings, and wings. Wing sorghum and ribs are made of titanium alloy. The oil pressure fitting is a Ti-3Al-2.5V alloy seamless tube, which reduces the quality of the system by more than 40%. In order to reduce the susceptibility to fatigue fracture and improve the service life of the system, the shaping and assembly of various tube parts are automated.