High strength: The density of titanium alloy is generally about 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 greater than other metal structural materials, and parts and components with high unit strength, good rigidity and light weight can be produced. At present, titanium alloys are used in aircraft engine components, skeletons, skins, fasteners and landing gear.
High thermal strength: The use temperature is several hundred degrees higher than that of aluminum alloy. It can still maintain the required strength at medium temperature and can work for a long time at a temperature of 450 to 500°C. Titanium alloy still has a high specific strength in the range of 150℃～500℃, while the specific strength of aluminum alloy decreases obviously at 150℃. The working temperature of titanium alloy can reach 500℃, while that of aluminum alloy is below 200℃.
Good corrosion resistance: Titanium alloy works in moist atmosphere and sea water, and its corrosion resistance is far better than stainless steel; it has strong resistance to pitting, acid corrosion and stress corrosion; it is organic to alkali, chloride and chlorine. Products, nitric acid, sulfuric acid, etc. have excellent corrosion resistance. However, titanium has poor corrosion resistance to media with reducing oxygen and chromium salts.
Good low temperature performance: Titanium alloy can still maintain its mechanical properties at low and ultra-low temperature. Titanium alloys with good low temperature performance and extremely 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: Titanium has high chemical activity, and produces a strong chemical reaction with O, N, H, CO, CO2, water vapor, ammonia, etc. in the atmosphere. When the carbon content is greater than 0.2%, it will form hard TiC in the titanium alloy; when the temperature is high, it will also form a hard surface layer of TiN titanium alloy products when it interacts with N; when the temperature is above 600℃, titanium absorbs oxygen to form a high hardness The hardened layer; the increase in hydrogen content will also form an embrittlement layer. The depth of the hard and brittle surface layer produced by absorbing gas can reach 0.1～0.15 mm, and the hardening degree is 20%～30%. Titanium also has a high chemical affinity and is easy to adhere to the friction surface.
