Titanium is a new metal, the performance of titanium is related to the content of carbon, nitrogen, hydrogen, oxygen and other impurities, the purest titanium iodide impurity content does not exceed 0.1%, but its strength is low, high plasticity. 99.5% of industrial pure titanium performance is: the rho = 4.5 g/cm3 density, melting point is 1725 ℃, coefficient of thermal conductivity of lambda = 15.24 W/(m.K), tensile strength of sigma b = 539 MPa, elongation delta = 25%, reduction of area bits = 25%, elastic modulus E = 1.078 x 105 MPa, hardness HB195.
1. High strength
The density of titanium alloy is generally about 4.51g/ cm3, and titanium alloy is only 60% of that of steel. The density of pure titanium is close to that of ordinary steel. Some high-strength titanium alloys exceed the strength of many alloy structural steels. Therefore, the specific strength (strength/density) of titanium alloy is much higher than that of other metal structural materials, as shown in table 7-1. Parts with high unit strength, good rigidity and light weight can be made. Aircraft engine components, skeleton, skin, fasteners and landing gear are all made of titanium alloy.
2. High thermal strength
The use temperature is several hundred degrees higher than aluminum alloy, in the medium temperature can still maintain the required strength, can work in 450 ~ 500℃ temperature for a long time these two kinds of titanium alloy in the range of 150℃ ~ 500℃ still have a very high specific strength, and aluminum alloy at 150℃ than the strength decreased significantly. The working temperature of titanium alloy can reach 500℃, while that of aluminum alloy is below 200℃.
3. Good resistance to corrosion
The corrosion resistance of titanium alloy is much better than that of stainless steel. It is especially resistant to pitting, acid and stress corrosion. Good corrosion resistance to alkali, chloride, chlorine, nitric acid, sulfuric acid, etc. However, titanium has poor corrosion resistance to medium with reducing oxygen and chromium salt.
4. Good low temperature performance
Titanium alloy can maintain its mechanical properties at low and ultra-low temperatures. Titanium alloys with good low temperature performance and very low clearance elements, such as TA7, can maintain a certain plasticity at -253℃. Therefore, titanium alloy is also an important low temperature structural material.
