Do you know all ten properties of titanium?

1, low density, high strength, specific strength The density of titanium is 4.51g/cm3, 57% of steel, titanium is less than twice as heavy as aluminium, and three times stronger than aluminium. Titanium alloy specific strength (strength / density ratio) is commonly used in industrial alloys in the largest (see Table 1), titanium alloy specific strength is stainless steel 3.5 times, aluminium alloys 1.3 times, magnesium alloys 1.7 times, so it is the aerospace industry is essential to the structure of the material. Table 1 Comparison of density and specific strength of titanium and other metals

2, excellent corrosion resistance The passivity of titanium depends on the presence of an oxide film, which is much better in oxidising media than in reducing media. High rate corrosion occurs in reducing media. Titanium does not corrode in some corrosive media, such as seawater, wet chlorine gas, chlorite and hypochlorite solutions, nitric acid, chromic acid, metal chlorides, sulphides and organic acids. However, in media that react with titanium to produce hydrogen (e.g. hydrochloric and sulphuric acids), titanium usually has a higher corrosion rate. However, if a small amount of oxidising agent is added to the acid, a passivation film is formed on the surface of titanium. Therefore, titanium is corrosion-resistant in strong sulphuric acid-nitric acid or hydrochloric acid-nitric acid mixtures, and even in hydrochloric acid containing free chlorine. The protective oxide film of titanium is often formed when the metal encounters water, even in small amounts of water or water vapour. If titanium is exposed to a strongly oxidising environment in the complete absence of water, rapid oxidation occurs and violent reactions, even spontaneous combustion, often occur. Such phenomena have occurred when titanium reacts with fuming nitric acid containing excess nitrogen oxide, and when titanium reacts with dry chlorine gas. So to prevent such reactions, there must be a certain amount of water.

3, good heat resistance Usually aluminium at 150 ℃, stainless steel at 310 ℃ that is the loss of the original performance, and titanium alloys at 500 ℃ or so still maintain good mechanical properties. When the aircraft speed reaches 2.7 times the speed of sound, the surface temperature of the aircraft structure reaches 230 ℃, aluminium alloys and magnesium alloys can not be used, while titanium alloys can meet the requirements. Titanium's heat resistance is good, it is used for aero-engine compressor discs and blades as well as aircraft fuselage skin.

4, good low-temperature performance Certain titanium alloys (such as Ti-5AI-2.5SnELI) strength with the lowering of the temperature increases, but the plasticity reduces not much, still have good ductility and toughness at low temperatures, suitable for use in ultra-low temperatures. Can be used in dry liquid hydrogen and liquid oxygen rocket engine, or in manned spacecraft for the use of ultra-low temperature containers and storage tanks.

5, non-magnetic Titanium is non-magnetic, it is used for submarine shells, will not cause the explosion of the mine.

6, thermal conductivity of small Titanium and other metal thermal conductivity comparison is shown in Table 2. Table 2 Comparison of titanium and other metal thermal conductivity Titanium's thermal conductivity is small, only for the steel of the 1 / 5, aluminium of 1 / 13, copper of 1/25. thermal conductivity Bad thermal conductivity is a disadvantage of titanium, but in some occasions you can use this feature of titanium.

7, low modulus of elasticity The modulus of elasticity of titanium is only 55% of that of steel, as a structural material, the low modulus of elasticity is a disadvantage.

8, tensile strength and yield strength is very close to the Ti-6AI-4V titanium alloy tensile strength of 960MPa, yield strength of 892MPa, only 58MPa difference between the two. 9, titanium and other metals thermal conductivity comparison 58MPa,

9, titanium is easy to be oxidised at high temperatures Titanium with a strong combination of hydrogen and oxygen, care should be taken to prevent oxidation and hydrogen absorption. Titanium welding should be carried out under argon protection to prevent contamination. Titanium tube and sheet to be heat-treated in a vacuum, titanium forgings heat treatment to control the micro-oxidative atmosphere.

10, low damping properties of titanium and other metal materials (copper, steel) made of the exact same shape and size of the bell, with the same force to each bell will find that the clock made of titanium oscillates up to the sound of the sound lasts for a long time, i.e., through the energy given to the bell by the knocking is not easy to disappear, so we say that titanium's Therefore, we say that titanium has low damping properties.