The density of titanium alloy is generally around 4.51g/cm3, which is only 60% of steel. The strength 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, which can produce zero and components with high unit strength, good rigidity and light weight. At present, the aircraft engine components, skeleton, skin, fasteners and landing gear are all made of titanium alloy.
High thermal strength, using temperature several hundred degrees higher than aluminum alloy, in the medium temperature can still maintain the required strength, can work in the temperature of 450 ~ 500℃ for a long time these two types of titanium alloy in the range of 150℃ ~ 500℃ still have a high specific strength, and aluminum alloy at 150℃ specific strength decreased significantly. The working temperature of titanium alloy can reach 500℃, while that of aluminum alloy is below 200℃.
Good corrosion resistance. Titanium alloy works in humid atmosphere and seawater medium, and its corrosion resistance is far better than stainless steel. Especially strong resistance to pitting corrosion, acid corrosion and stress corrosion; To alkali, chloride, chlorine organic goods, nitric acid, sulfuric acid and other excellent corrosion resistance. But titanium has poor corrosion resistance to reducing oxygen and chromium salt media.
The mechanical properties of titanium alloys can be maintained at both low and ultra-low temperatures. Titanium alloys with good low temperature performance and very low interstitial elements, such as Ta7, can maintain a certain degree of plasticity at -253℃. Therefore, titanium alloy is also an important low temperature structural material.
High chemical activity, the chemical activity of titanium is high, with O, N, H, Co, Co2, water vapor, ammonia gas and so on in the atmosphere produce strong chemical reaction. When the carbon content is greater than 0.2%, hard TiC will be formed in titanium alloy. When the temperature is high, the hard surface layer of TiN can also be formed when it interacts with N. At above 600℃, titanium absorbs oxygen to form a very hard hardened layer. When hydrogen content rises, a embrittlement layer is also formed.
