In recent years, because people’s living standards have been increasing day by day, and the demand for travel methods has become more convenient, the automobile industry has developed very rapidly, and the problems of fuel consumption, environmental protection and safety caused by automobiles have attracted increasing attention. The development direction of the automobile industry must be inseparable from light weight, low fuel consumption and low emissions.
According to the statistics of international authoritative departments, 60% of automobile fuel combustion energy is consumed by its own quality, although high-strength thin steel plates, aluminum, magnesium, metal matrix composites and plastic resin materials have played a role in reducing vehicle weight. Effect, but the emergence of industrial titanium materials has made car manufacturing a better choice. The good characteristics of titanium materials have been widely used in the automotive field.
Titanium alloys were first used in automobiles in the mass-produced high-end NSX V-6 car, and then in 1998 the titanium alloy material was used in the valves of Toyota’s award-winning convertible in 1998. The valve spring of this car also uses titanium, and its weight is reduced from 43g to 36g. Toyota’s new model initially produced 4,000 units, half of which used titanium.
In addition, examples of titanium used by other Japanese companies are Honda S2000 and R models. Some cars in Europe also use titanium in the mass production of the connecting shaft.
1.Engine connecting rod
Titanium alloy is an ideal choice for connecting rod materials. The engine connecting rod made of titanium alloy can effectively reduce the quality of the engine, improve the fuel utilization rate and reduce the exhaust volume. Compared with steel connecting rods, titanium connecting rods can reduce the quality of 15% to 20%. The materials used for titanium alloy connecting rods are mainly Ti-6Al-4V, Ti-10V-2Fe-3Al, Ti-3Al-2.0V, Ti-4Al-4Mo-Sn-0.5Si, etc. Other titanium alloy materials such as Ti-4Al -The application of 2Si-4Mn and Ti-7M-4Mo in connecting rods is also under development.
2. Engine Valve
Automotive engine valves made of titanium alloy can not only reduce the quality and extend the service life, but also reduce fuel consumption and improve the reliability of the car. Compared with steel valves, the quality of titanium valves can be reduced by 30% to 40%, and the limit speed of the engine can be increased by 20%. As far as the current application is concerned, the material of the intake valve is mainly Ti-6Al-4V, and the material of the exhaust valve is mainly Ti-6242S. Usually Sn and Al are added together to obtain lower brittleness and higher The strength of Mo; the addition of Mo can improve the heat treatment performance of the titanium alloy, strengthen the strength of the quenched and aged titanium alloy, and increase the hardness.
3. Valve spring seat
High strength and fatigue resistance are the properties that the valve spring seat must have. Beta titanium alloy is a heat treatment type alloy, which can obtain high strength through solution aging treatment. The corresponding more suitable materials are Ti-15V-3Cr- 3Al-3Sn and Ti-15Mo-3Al-2.7Nb-0.2Si. Mitsubishi Motors uses Ti-22V-4Al titanium alloy valve spring seats in its large-scale production cars, which reduces the mass of 42% compared with the original steel lock, the valve mechanism reduces the inertial mass by 6%, and the maximum engine speed increases 300r/min.
4. Titanium alloy spring
Titanium and its alloys have a lower modulus of elasticity than steel materials, and have a large σs/E value, which is suitable for manufacturing elastic elements. Compared with steel automobile springs, under the premise of the same elastic work, the height of the titanium spring is only 40% of the steel spring, and the mass is only 30% to 40% of the steel spring, which is convenient for the design of the car body. In addition, the excellent fatigue performance and corrosion resistance of titanium alloy can increase the service life of the spring. At present, the titanium alloy materials that can be used to manufacture automobile springs are Ti-4.5Fe6.8Mo-1.5Al and Ti-13V11C-3Al.
The turbocharger can improve the combustion efficiency of the engine and enhance the power and torque of the engine. The turbine rotor of the turbocharger needs to work in the high-temperature exhaust gas above 850 ℃ for a long time, so it needs to have good heat resistance. Traditional light metals such as aluminum alloys cannot be used due to their low melting points. Although ceramic materials are used in turbine rotors because of their light weight and high temperature resistance, their application is limited due to high cost and inability to optimize the shape. In order to solve these problems, Tetsui et al. developed the TiAl turbine rotor, which has been verified by many tests and not only has good durability and efficiency, but also improves the acceleration of the engine. This design has been successfully applied commercially in the Mitsubishi Lancer Evolution series.
6. Exhaust system and muffler
Titanium is widely used in the exhaust system of automobiles. The exhaust system made of titanium and its alloys can not only improve reliability, extend life and improve appearance, but also reduce quality and improve fuel combustion efficiency. Compared with the steel exhaust system, the quality of the titanium exhaust system can be reduced by about 40%. In the Golf series cars, the quality of the titanium exhaust system can be reduced by 7 to 9 kg. At present, the titanium used in the exhaust system is mainly industrial pure titanium.
The mass of muffler made of titanium is only 5-6kg, which is lighter than mufflers such as stainless steel. On the 2000 Chevrolet CorvetteZ06 car, a 11.8kg titanium muffler and exhaust pipe system was used to replace the original 20kg stainless steel system, reducing the quality by 41%. The system strength after replacement remains unchanged, making the car faster, more flexible in operation and saving fuel. The titanium used in the muffler is also mainly industrial pure titanium.
7. Body frame part
In order to improve the safety and reliability of automobiles, it is necessary to consider from the aspects of design and manufacturing, especially the manufacturing materials. Titanium is a very good material for making car body frames. It not only has higher specific strength, but also has good toughness. In Japan, automobile manufacturers choose pure titanium metal welded tubes to make body frames. This kind of frame can make the driver feel safe enough while driving.
8. Other titanium alloy parts
Used in engine rocker arms, suspension springs, engine piston pins, automotive fasteners, lug nuts, car door penetration beams, car stop brackets, brake caliper pistons, pin bolts, pressure plates, shift buttons and car clutch circles Board and other auto parts.
Advantages of titanium materials for automobiles:
Titanium alloy has the advantages of light weight, high specific strength, good corrosion resistance, etc., so it is widely used in the automotive industry. The most widely used titanium alloy is the automobile engine system. The use of titanium alloys to manufacture engine parts has many benefits, mainly manifested in:
1) The low density of titanium alloy can reduce the inertial mass of moving parts. At the same time, titanium valve spring can increase free vibration, reduce the body vibration, increase the engine speed and output power.
2) Reduce the inertial mass of moving parts, thereby reducing friction and improving the fuel efficiency of the engine.
3) The choice of titanium alloy can reduce the load stress of related parts and reduce the size of parts, thereby reducing the quality of the engine and the vehicle.
4) The reduction of the inertial mass of the parts makes the vibration and noise weaker and improves the performance of the engine.
The application of titanium alloy on other components can improve the comfort of people and the appearance of automobiles. In the automotive industry, titanium alloys play an inestimable role in energy saving and consumption reduction.
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