1. The specific strength of titanium tube is high. The density of titanium alloy is generally about 4.5g/cm3, only 60% of that 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 far greater than that of other metal structural materials, which can produce parts and components with high unit strength, good rigidity and light weight. At present, titanium alloy is used for engine components, framework, skin, fasteners and landing gear of aircraft.
2. The thermal strength of titanium tube is high. The service temperature is several times higher than that of aluminum alloy, and the required strength can still be maintained at medium temperature. The two titanium alloys can work at 450~500 ℃ for a long time. They still have high specific strength in the range of 150 ℃~500 ℃, while the specific strength of aluminum alloy decreases significantly at 150 ℃. The working temperature of titanium alloy can reach 500 ℃, while that of aluminum alloy is below 200 ℃.
3. Titanium tube has good corrosion resistance. The corrosion resistance of titanium alloy is much better than that of stainless steel when it works in humid atmosphere and seawater; The resistance to pitting, acid corrosion and stress corrosion is particularly strong; It has excellent corrosion resistance to alkali, chloride, chlorine organic substances, nitric acid, sulfuric acid, etc. However, titanium has poor corrosion resistance to reducing oxygen and chromate media.
4. Titanium tube has good low-temperature performance. Titanium alloy can still maintain its mechanical properties at low and ultra-low temperatures. Titanium alloys with good low-temperature performance and very low interstitial elements, such as TA7, can maintain certain plasticity at - 253 ℃. Therefore, titanium alloy is also an important low-temperature structural material.
5. Titanium tube has high chemical activity. The chemical activity of titanium is large, and it has 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%, hard TiC will be formed in titanium alloy; When the temperature is high, the hard surface of TiN will also be formed by the interaction with N; At above 600 ℃, titanium absorbs oxygen to form a hardened layer with high hardness; The embrittlement layer will also be formed when the hydrogen content increases. The chemical affinity of titanium is also large, and it is easy to adhere to the friction surface.
6. Titanium tube has low thermal conductivity and elastic modulus. The thermal conductivity and elastic modulus of titanium are small. The elastic modulus of titanium alloy is about 1/2 of that of steel, so its rigidity is poor and it is easy to deform. It is not suitable to make slender rods and thin-walled parts. During cutting, the rebound amount of the machined surface is large, about 2~3 times of that of stainless steel, resulting in severe friction, adhesion and adhesive wear of the tool flank.