Aerospace boosts the development of titanium industry
The titanium industry is rising with the development of aerospace industry. Without titanium alloy, there would be no prosperous aerospace industry today, which is no exaggeration. One generation of materials and one generation of equipment, if there is no high-temperature titanium alloy, it will not be possible to build a powerful aeroengine, and supersonic aircraft will be difficult to come out.
Titanium has a series of advantages. The first is that the density is moderate, 4.51g/cm3, which is 57% of steel. It is only a little larger than half of steel, a little smaller than twice that of aluminum, but its strength is 3 times higher than that of aluminum. Among common structural alloys, titanium alloy has a higher specific strength zui, 3.5 times that of stainless steel, 1.3 times that of aluminum alloy, and 1.7 times that of magnesium alloy. This only makes it an indispensable material for aerospace structural parts.
Titanium also has the performance advantages of "four highs and one none". High corrosion resistance, high heat resistance, high yield strength and low temperature performance. Titanium has high corrosion resistance in seawater, wet chlorine, chlorite, nitric acid, chromic acid, metal chloride, sulfide and organic acid; Titanium alloys still have high mechanical properties at 500 ℃. Some titanium alloys have both high mechanical properties and high plasticity and toughness at low temperatures; Titanium alloy has very high yield strength, for example, the tensile strength of Ti-6AL-4V alloy is 960MPa, and the yield strength is 892MPa, only 58MPa difference; Titanium and titanium alloys are nonmagnetic, nonmagnetic and have high strength properties. They are excellent materials for making deep-sea submarine shells.
Of course, titanium and titanium alloys are not materials that combine advantages. They also have four disadvantages: first, they have low thermal conductivity, which is only 1/5 of that of steel. That is, the heat conduction is slow, and the heating time is long, and the cooling time is long after being heated; Second, the elastic modulus is small. Its elastic modulus is only 55% of that of iron, and its anti deformation ability is not as good as that of steel. As a structural material, small elastic modulus is not a good thing; Third, titanium is highly active, easy to oxidize at high temperatures, and easy to combine with hydrogen and oxygen to form hydrogen embrittlement. Therefore, argon must be used for protection during welding. Titanium tubes and sheets should be heat treated in vacuum, and forgings can be heat treated in micro oxidation atmosphere; The damping resistance of titanium and titanium alloys is low, which is also its disadvantage.
In 1950, the United States used industrial pure titanium to manufacture the rear fuselage heat shield, wind deflector, tail cover and other non load-bearing parts of the F84 fighter bomber, which was the first time titanium was used in aircraft. Since then, the application of titanium alloys in aerospace and spacecraft has been increasing year by year, and more applications have been made in marine ships, weapons lightweight and other aspects. With the wide application of titanium, it also promotes the research and development of titanium alloys in the field of material research. Many titanium alloys with high strength, high elasticity, good weldability and comprehensive properties have been developed and produced, overcoming the performance shortcomings of pure titanium metal, and meeting the requirements for materials under different working environments and stress conditions. At present, 100 brands of titanium alloys have been successfully researched and applied under the conditions of high temperature, high strength and high comprehensive performance requirements such as aerospace. The R&D and application of titanium products of various alloy brands have greatly promoted the use of titanium metal and promoted the development of titanium industry.
China's titanium industry started in the 1960s. In 1995, the sponge titanium plant was built in Zunyi, and the titanium metal smelting and processing plant was built in Baoji. At the initial stage, the annual output of titanium materials increased from tens of tons to 90, and the total output of titanium processing materials was about 500 tons. During this period, China solved the problem of whether it produced titanium materials by itself. After 2000, with the development of national defense and economic society in China, titanium and titanium alloys have been widely used in aerospace, ships, petrochemical industry, weapons and equipment, which has promoted the rapid development of titanium industry. By 2020, the sales volume of titanium materials in China will reach 80000 tons, and the use of sponge titanium will reach 120000 tons. In the past two decades, China's titanium industry has been in a leading position in the history of the world's titanium industry, providing advanced titanium alloy materials for our national defense industry.
