What are the advantages of titanium alloy?
Titanium alloys for automobiles have the characteristics of low density, excellent mechanical properties, good biocompatibility, corrosion resistance, high-temperature resistance, and good low-temperature toughness. They have been widely used in the field of automobile manufacturing. The density of titanium alloy is only 60% of steel, but the strength can reach more than 800MPa. It still maintains good mechanical properties at around 500℃ and has good welding and forming properties. It has been used in the manufacturing of racing cars more than 20 years ago. The mass of the racing engine is greatly reduced while improving the engine's performance.
At present, titanium alloy parts used in automobile manufacturing are mainly distributed in automobile exhaust systems, engine systems, transmission and vibration damping systems, and body frames.
How is titanium used in the automotive industry?
1. Exhaust system
Automobile exhaust system materials are required to have good high-temperature mechanical properties and resistance to corrosion by S and Cl elements. Traditional exhaust valve assemblies are made of stainless steel, but titanium alloys are more suitable as exhaust valve materials in terms of performance.
The titanium air return pipe used in the new Chevrolet Corvette Z206 car effectively avoids problems such as pitting corrosion and weld corrosion on stainless steel pipes. It also improves fuel combustion efficiency and acceleration capabilities and shortens braking distances.
Timet, the largest Titanium alloys for automobiles manufacturer in the United States, has been committed to the R&D and manufacturing of titanium alloy exhaust systems. Many Japanese companies have also carried out related research and development work. Currently, Fuji Heavy Industries Co., Ltd. has produced a limited number of 440 sets of titanium alloy vehicle exhaust systems. trachea.
2. Engine system
The automobile engine system is the most commonly used component of titanium alloy in the automotive field. The main applications of titanium alloy in the engine system include valves, connecting rods, crankshafts, valve seats, and other components.
Japan's Honda Motor Co. uses forged titanium connecting rods in its NSX racing V-6 engine; Mitsubishi Motors Corp. uses titanium valve spring seats in high-volume, four-cylinder engines, and titanium connecting rods are used in Porsche cars.
(1) Valve
In terms of titanium alloy valves, both the United States and Japan have conducted a lot of research work. The United States currently uses Ti-6Al-4V alloy to make intake valves and Ti-6Al-2Sn-4Zr-2Mo alloy to make exhaust valves; while Japan Toyota uses Ti-6Al-4V/Ti B alloy to prepare intake valves and Ti-Al-Zr-Sn-Mo-Nb-Si/Ti B alloy to prepare exhaust valves. These types of titanium alloys have good high-temperature mechanical properties, oxidation resistance, and creep resistance, which can effectively improve engine performance and increase vehicle speed.
(2) Valve seat
Titanium alloy valve seats have been widely used in racing cars and sports cars, with more than 250,000 sets produced every year. They are mainly made of Ti-6Al-4V or Ti-5Al-2Cr-1Fe alloy. Since the shape of the valve seat is relatively simple, it is widely used in The requirements for mechanical processing are not high, and no special surface treatment is required. The cost is relatively cheap, and the effect is obvious in terms of weight reduction of automobiles.
(3) Connecting rod
The use of titanium alloy connecting rods can effectively reduce the mass of the engine and improve vehicle performance. At present, the main preparation material is Ti-6Al-4V alloy. Daido Co., Ltd. of Japan is currently developing a two-phase titanium alloy Ti-3Al-2V-0.2Si-0.47Ce-0.27La. This alloy has good machinability and is also excellent in mechanical properties, fatigue properties, and corrosion resistance. , it is expected to be used in connecting rod parts that undergo rapid acceleration and deceleration of engines.
(4) Crankshaft
Although titanium alloy crankshafts are not widely used at present, the Ti-3Al-2.5V alloy specially developed by Japan has been verified on Honda racing cars. It effectively reduces the mass and increases the engine speed by 700r/min, proving the titanium Advantages of an alloy crankshaft. At the same time, Japan is already trial-producing a Ti-5Al-2Cr-Fe alloy crankshaft and hopes that titanium alloy will be more widely used in crankshaft components.
3. Vibration reduction system
The core component of the automobile vibration-damping suspension system is the suspension spring. Compared with ordinary automobile spring steel, titanium alloy has higher specific strength, lower shear modulus, and higher fatigue strength, making it more suitable for manufacturing automobile damping springs. Since the deflection of the spring is proportional to the number of turns and inversely proportional to the shear modulus of the material, titanium alloy springs require fewer turns than steel springs to achieve the same spring response, effectively reducing the mass of the spring. , saving space.
At the same time, titanium alloy springs can also effectively increase the resonant frequency of the spring and extend its service life. At present, most titanium alloy springs are made of single-phase beta titanium alloy. The German Volkswagen Company has used Lupo FSI titanium alloy gear springs in some cars, with approximately 3,500 vehicles used.
4. Body frame
In terms of vehicle body frame components, titanium alloy’s higher specific strength, lower density, and good corrosion resistance all indicate that it is a good material for vehicle body frame preparation. At present, some automobile companies are already using titanium alloys in parts such as gear brackets and brake caliper pistons. Among transmission components, Japan is currently developing a process for preparing titanium alloy casings by high-speed spinning. Compared with steel casings, titanium alloy casings can better reduce the impact of the flywheel and have better buffering effects.
In addition, titanium alloys are also used in automotive fasteners and other components. With the continuous development of titanium alloy preparation processes and the automotive industry, titanium alloys will surely be used more in automotive parts.
5. The significance of titanium alloys to automobile lightweighting
Calculations by foreign research institutions have found that when the vehicle's overall quality is reduced by 10%, fuel consumption can be reduced by 6% to 8%. Some studies have shown that for every 91kg weight reduction in a car, an average of 0.43km more mileage per liter of fuel can be achieved. Therefore, with the continuous development of my country's economy and the increasing number of automobiles, automobile lightweight has become one of the important ways to reduce energy consumption and reduce air pollution.
Titanium and titanium alloy materials are currently widely used in automotive parts due to their excellent physical and chemical properties. The use of titanium materials not only effectively improves the performance and safety factor of automobiles, but also plays an important role in lightweight automobiles, effectively reducing the weight of automobiles and reducing fuel consumption.
Compared with the traditional stainless steel system, the automobile exhaust system uses a titanium tail nozzle-return pipe assembly, which can save approximately 8.2kg in weight. In engine parts such as valves and connecting rods, the use of titanium alloy products instead of traditional steel and cast iron materials can effectively reduce the weight of the engine.
According to research in the Japanese automotive industry, automotive power valves use about 0.8kg of titanium material parts, which is equivalent to the effect achieved by 20kg of steel parts; each titanium valve seat can reduce the mass by about 10g compared with steel valve seats; even The rods and crankshaft are made of titanium alloy, which is most effective in reducing engine mass.
In the vibration damping system, each titanium alloy spring can reduce the mass by more than 60% compared to steel springs. Calculated with 4 suspension springs per vehicle, after switching to titanium alloy springs, each vehicle can lose 9~13.6kg in weight. In addition, the mass of the titanium alloy silencer is only 5~6kg, which is 40% lighter than the stainless steel silencer.
Taking an ordinary medium-sized car as an example, if existing titanium alloy auto parts are used to replace traditional parts, the curb weight of the car will be reduced from about 1,500kg to about 1,000kg. The weight reduction rate can reach 30%, and the overall fuel consumption can be reduced by 20%. Above all this will greatly reduce fuel consumption around the world and effectively alleviate the problems of energy shortage and environmental pollution.
The above data shows that the use of titanium alloys has obvious effects in light-weighting automobiles. In the modern automobile industry, the application technology of titanium and titanium alloys in automobile parts should be continuously developed to increase the proportion of titanium alloys used in automobiles.
At present, the application of titanium alloys in my country's automobile industry is still in the experimental stage. The main problems are that the cost of titanium alloy materials is too high and parts are difficult to process.
Therefore, the main task in the future should be to reduce the price of titanium alloy parts by developing cheap titanium alloy materials, reducing the production cost of titanium alloy raw materials, and improving the processing efficiency of titanium alloy parts by improving the processing technology.
Foreign experience shows that only by uniting the automobile design and manufacturing parties and the titanium alloy developers can we provide higher-quality titanium alloy materials for automobiles.
It is believed that with the continuous deepening of research and development work, titanium alloys for automobiles will play an increasingly important role in my country's modern automobile industry and promote the continuous development of the automobile industry.
