Question 2: What is the material of titanium alloy? It is metallic titanium with excellent performance and light weight, and its specific gravity is half that of steel. High strength, the same as stainless steel. Processing is difficult.
Question 3: What are the main uses of titanium alloys? Titanium alloy has high strength, low density, good mechanical properties, good toughness and corrosion resistance. In addition, titanium alloy has poor technological performance, difficult cutting and easy absorption of impurities such as hydrogen, oxygen, nitrogen and carbon during hot working. In addition, the wear resistance is poor and the production process is complicated. The industrial production of titanium began in 1948. With the development of aviation industry, titanium industry develops at an average annual rate of about 8%. At present, the annual output of titanium alloy processing materials in the world has reached more than 40 thousand tons, and there are nearly 30 kinds of titanium alloy brands. The most widely used titanium alloys are Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (Ta7) and industrial pure titanium (TA 1, TA2 and TA3).
Titanium alloys are mainly used to manufacture compressor parts of aircraft engines, followed by structural parts of rockets, missiles and high-speed aircraft. In the mid-1960s, titanium and its alloys have been used in general industries, such as electrodes in electrolysis industry, condensers in power stations, heaters for oil refining and seawater desalination, and environmental pollution control devices. Titanium and its alloys have become a corrosion-resistant structural material. In addition, it is also used to produce hydrogen storage materials and shape memory alloys.
Titanium alloy is a new important structural material used in aerospace industry. Its specific gravity, strength and service temperature are between aluminum and steel, but its specific strength is high, and it has excellent seawater corrosion resistance and ultra-low temperature performance. Titanium alloy 1950 was first used as a non-load-bearing component such as the rear fuselage heat shield, wind deflector and tail shield on the F-84 fighter-bomber in the United States. In the 1960s, titanium alloy was used in the middle fuselage instead of the rear fuselage, partially replacing structural steel to manufacture important load-bearing components such as frames, beams and flap guides. The usage of titanium alloy in military aircraft has increased rapidly, reaching 20% ~ 25% of the structural weight of the aircraft. Since 1970s, titanium alloys have been widely used in civil aircraft. For example, Boeing 747 used more than 3640 kilograms of titanium. For aircraft with Mach number less than 2.5, titanium is mainly used to replace steel to reduce structural weight. Another example is the American SR-7 1 high-altitude high-speed reconnaissance plane (flying Mach number 3, flying altitude 262 12m), in which titanium accounts for 93% of the structural weight of the aircraft, so it is called "all-titanium" aircraft. When the thrust-to-weight ratio of aero-engine is increased from 4 ~ 6 to 8 ~ 10, and the compressor outlet temperature is correspondingly increased from 200 ~ 300℃ to 500 ~ 600℃, the original titanium alloy low-pressure compressor disc and blade made of aluminum must be replaced by titanium alloy, or the high-pressure compressor disc and blade should be replaced by titanium alloy stainless steel to reduce the structural weight. In 1970s, titanium alloy was generally used in aero-engines, accounting for 20% ~ 30% of the total structural weight, and was mainly used to manufacture compressor parts, such as forging titanium fans, compressor disks and blades, casting titanium compressor casings, intermediate casings and bearing housings. Spacecraft mainly uses the high specific strength, corrosion resistance and low temperature resistance of titanium alloy to manufacture various pressure vessels, fuel tanks, fasteners, instrument belts, frames and rocket shells. Titanium alloy plate weldments are also used in artificial earth satellites, lunar modules, manned spacecraft and space shuttles.
Question 4: What are the main uses of titanium alloys? (1) high strength
The density of titanium alloy is about 4.5g/cm3, which is only 60% of that of steel. The strength of pure titanium is close to that of ordinary steel, and the strength of some high-strength titanium alloys exceeds that 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 manufactured. At present, titanium alloys are used in aircraft engine parts, skeletons, skins, fasteners and landing gears.
(2) High heat intensity
The service temperature is several hundred degrees higher than that of aluminum alloy, and the required strength can still be maintained at moderate temperature, and it can work for a long time at 450 ~ 500℃. These two titanium alloys still have 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℃.
(3) Good corrosion resistance
Titanium alloy works in humid atmosphere and seawater medium, and its corrosion resistance is far superior to that of stainless steel. Especially strong resistance to pitting corrosion, acid corrosion and stress corrosion; Excellent corrosion resistance to alkali, chloride, chlorine, nitric acid, sulfuric acid and other organic substances. However, the corrosion resistance of titanium to reducing oxygen and chromium salt medium is poor.
(4) Good low temperature performance
Titanium alloy can still maintain its mechanical properties at low temperature and ultra-low temperature. Titanium alloys, such as TA7, which have good low temperature performance and extremely low interstitial elements, can still maintain certain plasticity at -253℃. Therefore, titanium alloy is also an important low-temperature structural material.
(5) high chemical activity
Titanium has great chemical activity and has strong chemical reactions with O, N, H, CO, CO2, water vapor and ammonia in the atmosphere. When the carbon content is greater than 0.2%, the hard TiC will be made of titanium alloy; When the temperature is high, the reaction between TiN and n will also form a hard surface layer; When the temperature is higher than 600℃, titanium absorbs oxygen to form a hardened layer with high hardness. When the hydrogen content increases, a brittle layer will also be formed. The depth of hard and brittle surface layer produced by gas absorption can reach 0. 1 ~ 0. 15 mm, and the hardening degree is 20% ~ 30%. Titanium also has strong chemical affinity and is easy to adhere to the friction surface.
(6) Low thermal conductivity and low elastic modulus
The thermal conductivity λ= 15.24W/(m.K) of titanium is about 1/4 of nickel, 1/5 of iron and1/0/4 of aluminum, while the thermal conductivity of various titanium alloys is about 50% lower than that of titanium. The elastic modulus of titanium alloy is about 1/2 of steel, so it has poor rigidity and is easy to deform, and is not suitable for making slender rods and thin-walled parts. When cutting, the springback of the machined surface is very large, about 2 ~ 3 times that of stainless steel, which leads to serious friction, adhesion and bond wear on the tool flank.
Question 5: Classification of titanium alloys Titanium is an allotrope isomer with a melting point of 1668℃ and a close-packed hexagonal lattice structure below 882℃, which is called α titanium; It has a body-centered cubic lattice structure above 882℃, which is called β titanium. Using the different characteristics of the above two structures of titanium, adding appropriate alloying elements, and gradually changing the phase transformation temperature and phase content, titanium alloys with different structures can be obtained. At room temperature, titanium alloys have three matrix structures, which can be divided into the following three categories: α alloy, (α+β) alloy and β alloy. China is represented by TA, TC and TB respectively. It is a dual-phase alloy with good comprehensive properties, good organizational stability, good toughness, plasticity and high-temperature deformation properties, and can be well strengthened by hot pressing, quenching, aging and other processes. The strength after heat treatment is about 50% ~ 100% higher than that after annealing. It has high high temperature strength, can work at 400℃ ~ 500℃ for a long time, and its thermal stability is not as good as that of α titanium alloy. Among the three titanium alloys, the most commonly used are α titanium alloy and α+β titanium alloy. The machinability of α titanium alloy is the best, followed by α+β titanium alloy and β titanium alloy is the worst. Alpha titanium alloy code TA, beta titanium alloy code TB, alpha+beta titanium alloy code TC. Titanium alloys can be divided into heat-resistant alloys, high-strength alloys and corrosion-resistant alloys (titanium molybdenum, titanium palladium alloys, etc.). ), low temperature alloys and special functional alloys (titanium-iron hydrogen storage materials and titanium-nickel memory alloys). The composition and properties of typical alloys are shown in the table. Different phase composition and microstructure can be obtained by adjusting the heat treatment process of titanium alloy. It is generally believed that fine equiaxed structures have good plasticity, thermal stability and fatigue strength; Needle-like structure has high endurance strength, creep strength and fracture toughness; The equiaxed and needle-like mixed structures have good comprehensive properties.
Question 6: What's the difference between titanium alloy and stainless steel? One is soft and the other is hard. The same thing is that it does not rust.
Question 7: What are the uses and types of titanium alloys? Classification of titanium alloys
Titanium is an allotrope isomer with a melting point of 1720℃, and a close-packed hexagonal lattice structure below 882℃, which is called α titanium; It has a body-centered cubic structure above 882℃, which is called β titanium. Using the different characteristics of the above two structures of titanium, adding appropriate alloying elements, and gradually changing the phase transformation temperature and phase content, titanium alloys with different structures can be obtained. At room temperature, titanium alloys have three matrix structures, which can be divided into the following three categories: α alloy, (α+β) alloy and β alloy. China is represented by TA, TC and TB respectively. [Edit this paragraph] The purpose of titanium alloy Titanium alloy has high strength, low density, good mechanical properties, good toughness and corrosion resistance. In addition, titanium alloy has poor technological performance, difficult cutting and easy absorption of impurities such as hydrogen, oxygen, nitrogen and carbon during hot working. In addition, the wear resistance is poor and the production process is complicated. The industrial production of titanium began in 1948. With the development of aviation industry, titanium industry develops at an average annual rate of about 8%. At present, the annual output of titanium alloy processing materials in the world has reached more than 40 thousand tons, and there are nearly 30 kinds of titanium alloy brands. The most widely used titanium alloys are Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (Ta7) and industrial pure titanium (TA 1, TA2 and TA3).
Titanium alloys are mainly used to manufacture compressor parts of aircraft engines, followed by structural parts of rockets, missiles and high-speed aircraft. In the mid-1960s, titanium and its alloys have been used in general industries, such as electrodes in electrolysis industry, condensers in power stations, heaters for oil refining and seawater desalination, and environmental pollution control devices. Titanium and its alloys have become a corrosion-resistant structural material. In addition, it is also used to produce hydrogen storage materials and shape memory alloys.
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