Ti-6Al-4V alloy is widely used as the shell material of the first-stage rocket engine in the United States. The alloy is also used in: giant cylindrical liquid rocket containers; multiple spherical and oval engine casings for intercontinental ballistic missiles and "Minuteman" missiles, etc. On the other hand, because Ti-6Al-4VELI and Ti-5Al-2.5SnELI alloys have a low content of interstitial elements, especially oxygen, and can be used at ultra-low temperatures, these alloys are used as liquid hydrogen containers for rockets and missiles, and for "Mercury" spacecraft And the airtight module of the "Gemini" spacecraft, and the main structural parts of the "Apollo" spacecraft that successfully landed on the moon.
In addition to the use of industrial pure titanium, Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-6Al-4VELI, and Ti-5Al-2.5SnELI in titanium and titanium alloys used in the aerospace industry, there is also Ti-7Al-4Mo, Ti-3Al-2.5V, Ti-13V-1Cr-Ti-15V-3Cr-3Sn-3Al, and Ti/B-Al composite materials.
The space shuttle is the earliest manned spaceship in the world that can be used repeatedly. Development began in 1972, and the first flight was successful in 1981. The spaceship consists of an aircraft with small wings, a 47m long external fuel container, and 2 solid fuel rocket boosters totaling 500t.
The orbital spacecraft is 37m long and weighs about 68t. This size is roughly the same as the jet transport aircraft DC-9. It is the largest manned spacecraft so far. Its cargo compartment is 18m long and 5m in diameter and can transport 29.5t of cargo to Earth orbit.
The space shuttle can be launched like a rocket, and like a spaceship, it can fly in an orbit with a maximum altitude of 1000km and can glide and land like an airplane without thrust. This space shuttle is essentially a space transport ship, so one of the parameters for judging its usefulness is the amount of payload transported between the earth and the earth's orbit. To maximize this payload, titanium alloys are an important material for aerospace motor components.
The design life of the orbiting spacecraft is 100 flights, and each flight stays in space for 7 to 30 days. The spacecraft is manned, so it is designed to adapt to the space environment (vacuum, extreme temperature difference on the orbit, heat when re-entering the atmosphere, etc.), and is used repeatedly.
1. High-pressure vessel
Titanium alloys are used in many places because they can reduce the overall weight of spacecraft orbiting vehicles. The main use part of titanium is the high-pressure container filled with the necessary fuel and gas. The lightweight titanium alloy container was successfully developed on NASA's Gemini spacecraft and Apollo spacecraft, using Ti-6Al-4V alloy. The iron pressure vessel on the Apollo spacecraft has actually used an unprecedented design with a safety factor of 1.5, which was previously designed with a safety factor of about 4. In order to further reduce the weight of the high-pressure storage container of the orbiting space shuttle, the method of adding white sparrow fiber to the surface of the thin-walled titanium container is adopted.
Pressure vessel for storing compressed gas. The "Prowler" satellite and booster share 14 titanium containers, reducing the mass by 272kg.
A pressure vessel for storing liquid propellants. About 50 pressure vessels were used on the "Apollo" spacecraft, 85% of which were made of titanium. Hercules Ⅲ transition stage engine, the weight is reduced by 35% after switching to a titanium alloy propellant tank.
2. Engine housing
Solid fuel rocket motor case. The second-stage rocket engine of the "Minuteman" intercontinental missile uses Ti64 alloy to reduce the weight by 30% to 40%.
Liquid fuel rocket motor case. The pressure shell of the combustion chamber of the "Apollo" lunar module descending engine is made of Ti64 alloy.
3. Various structural parts
There are 7 types of titanium alloy grades used in the "Gemini" spacecraft, and 570kg of titanium parts are used, accounting for 84% of the structural weight. The brackets, fixtures, and fasteners of the "Apollo" spacecraft are all made of titanium, using a total of 68t titanium.
4. Hydraulic piping
The oil pressure piping of the space shuttle uses seamless pipes made of Ti-3Al-2.5V alloy. Due to the use of this alloy, the weight can be reduced by more than 40%. In order to reduce the sensitivity to fatigue fracture and improve the actual life of the system, various The assembly of tubes uses automatic forming.
