What are the advantages and disadvantages of titanium alloys?
1. Advantages
1. High strength. The density of titanium alloy is generally about 4.51g/cm3, which is only 60% 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.
2. The thermal strength is high. The service temperature is several hundred degrees higher than that of aluminum alloy. It can still maintain the required strength at medium temperature. It can work for a long time at a temperature of 450-500℃. These two types of titanium alloys are in the range of 150℃～500℃ There is still a high specific strength inside, while the specific strength of aluminum alloy decreases significantly at 150°C. The working temperature of titanium alloy can reach 500℃, while that of aluminum alloy is below 200℃.
3. Good corrosion resistance. Titanium alloy works in moist atmosphere and sea water, and its corrosion resistance is far better than stainless steel; it is particularly resistant to pitting, acid corrosion and stress corrosion; it is resistant to alkali, chloride and chlorine. Organic materials, nitric acid, sulfuric acid, etc. have excellent corrosion resistance. However, titanium has poor corrosion resistance to media with reducing oxygen and chromium salts.
4. 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 extremely low interstitial elements, such as TA7, can maintain a certain degree of plasticity at -253°C. Therefore, titanium alloy is also an important low-temperature structural material.
5. The chemical activity of titanium is high, and it has strong chemical reaction with O, N, H, CO, CO2, water vapor and ammonia in the atmosphere.
6. The thermal conductivity is small. The thermal conductivity of titanium λ=15.24W/(mK) is about 1/4 of nickel, 1/5 of iron, and 1/14 of aluminum. The thermal conductivity of various titanium alloys is higher than that of titanium. The coefficient drops by about 50%. 2.
Disadvantages
1. The main limitation of titanium and titanium alloys is their poor chemical reactivity with other materials at high temperatures. This property forces titanium alloys to be different from the general traditional refining, melting and casting techniques, and even often causes mold damage.
2. The price of titanium alloy has become very expensive. Therefore, they were mostly used in aircraft structures, aircraft, and high-tech industries such as petroleum and chemical industries.