Applications of Titanium Alloys in aerospace

The application of titanium in the aerospace industry mainly uses its low density, high strength, high temperature resistance, corrosion resistance and other properties.

The application of titanium in the space industry has also achieved the purpose of reducing launch weight, increasing range and saving costs, and is a popular material in the space industry. In the rocket, missile and space industry can be used as pressure vessels, fuel tanks, rocket engine shell, rocket nozzle sleeve, satellite shell, manned spacecraft cabin (skin and structural skeleton), landing gear, lunar module, propulsion system, etc.

In the United States, Ti-6Al-4V alloy is widely used for the shell material of the first stage rocket engine. The alloy is also used in giant cylindrical liquid rocket vessels; Intercontinental ballistic missiles, "Minuteman" missiles and a number of spherical and elliptical engine housing. On the other hand, Ti-6Al-4VELI and Ti-5Al-2.5SnELI alloys have low interstitial elements, especially oxygen, and can be used at ultra-low temperatures, so these alloys are used as liquid hydrogen containers for rockets and missiles, as well as sealed compartments for Mercury spacecraft and Gemini spacecraft. And the main structural components of the Apollo spacecraft that successfully landed on the moon.

In addition to the titanium and titanium alloys used in the aerospace industry, industrial pure titanium, Ti-6Al-4V, Ti-5al-2.5SN, Ti-6Al-4VELI and Ti-5Al-2.5SnELI are used. There are also Ti-7al-4Mo, Ti-3al-2.5V, Ti-13V-1CR-Ti-15V-3CR-3SN-3Al and Ti/B-Al composites.

The space shuttle is the world's first manned spacecraft that can be used repeatedly. Development began in 1972 and the first flight was successful in 1981. The spacecraft consists of a small winged vehicle, a 47m-long external fuel vessel and two solid-fuel rocket boosters totaling 500 tons.

Orbital spacecraft, 37m long, weighs about 68t, the size of the jet transport DC-9 is roughly the same, is the largest manned spacecraft to date, its cargo bay length of 18m, diameter of 5m, can transport 29.5 tons of cargo to Earth orbit.

The space shuttle can be launched like a rocket and fly like a spaceship in an orbit at a maximum altitude of 1,000 kilometers, and glide to land like an airplane without thrust. The shuttle is essentially a space transport vehicle, so one of the parameters to judge its usefulness is the payload it can carry to and from Earth and Earth orbit. In order to maximize this effective load, titanium alloy has become an important material for aerospace motor components.

The design life of the orbiting spacecraft is 100 flights, 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 differences in orbit, heat during re-entry into the atmosphere, etc.), and repeated use.

01 High Pressure vessel

Titanium alloys are used in many places because they reduce the total weight of spacecraft orbiting orbiters. The main use of titanium is the high pressure vessel into which the necessary fuels and gases are loaded. Lightweight titanium alloy container, developed successfully on NASA's Gemini spacecraft and Apollo spacecraft, using Ti-6Al-4V alloy. The iron pressure vessel on the Apollo spacecraft has actually used the unprecedented design of a safety factor of 1.5, which was previously designed with a safety factor of about 4. In order to make the high pressure storage container of the orbital space shuttle further lightweight, the method of adding white bird fiber (aromatic organic fiber produced by DuPont Company in the United States) on the surface of the thin-walled titanium container is adopted.

A pressure vessel for storing compressed gas. The Prowler satellite and booster shared 14 titanium containers, with a total mass reduction of 272kg.

Pressure vessel for storing liquid propellant. Of the 50 or so pressure vessels used on the Apollo spacecraft, 85 percent were made of titanium. The weight of Hercules III transition engine was reduced by 35% after switching to titanium propellant tank.

02 Engine Housing

Solid fuel rocket motor housing. "Minuteman" intercontinental missile second stage rocket engine using Ti64 alloy weight reduction of 30% to 40%.

Liquid fuel rocket motor housing. The pressure shell of the combustion chamber of the Apollo lunar module descent engine is made of Ti64 alloy.

03 Various structural parts

Titanium alloys are also widely used in various structural parts. The pressure chamber of the Mercury spacecraft is mainly titanium, which accounts for 80% of the weight of the cabin. "Gemini" spacecraft used seven titanium alloy grades, the use of titanium parts 570kg, accounting for 84% of the weight of the structure. The brackets, clamps and fasteners of the Apollo spacecraft are all made of titanium, using a total of 68 tons of titanium.

04 Oil pressure piping

The space shuttle oil pressure piping is made of Ti-3Al-2.5V alloy seamless pipe, due to the use of the alloy, the weight can be reduced about more than 40%, in order to reduce the sensitivity to fatigue fracture and improve the actual life of the system, various pipe assembly using automatic forming.