Titaaniseoksen käyttö autojen kevyessä valmistuksessa
Titanium and titanium alloys are characterized by low density, excellent mechanical properties, good biocompatibility, corrosion resistance, high temperature resistance, low temperature toughness, etc., and have been widely used in the field of automobile manufacturing.
Titanium alloy density is only 60% of steel, and the strength can reach more than 800MPa, at about 500℃ still maintain good mechanical properties, and welding and formability are better, more than 20 years ago has been applied to the manufacturing of racing cars, greatly reduce the quality of racing engine, while improving engine performance.
At present, titanium alloy components used in automobile manufacturing are mainly distributed in automobile exhaust system, engine system, transmission and vibration reduction system, and body frame parts.
1. Exhaust system
The material of automobile exhaust system is required to have good high temperature mechanical properties and corrosion resistance of S and Cl elements. Conventional exhaust components are made of stainless steel, but titanium alloy has been found to be more suitable for exhaust material in terms of performance.
The titanium return pipe used in the new Chevrolet Corvette Z206 effectively avoids pitting and weld corrosion problems of stainless steel pipes, while improving fuel efficiency and acceleration, and reducing braking distance.
Timet, the largest titanium manufacturer in the United States, has been working on the development and manufacturing of titanium exhaust systems. Several Japanese companies are also working on the development of titanium exhaust systems. Fuji Heavy Industries Co., Ltd. has produced a limited number of 440 titanium exhaust pipes for vehicles.
2. Engine system
Automotive engine system is the most used titanium alloy components in the automotive field, titanium alloy in the application of engine system mainly valve, connecting rod, crankshaft, valve seat and other parts.
Japan's Honda Motor company used forged titanium rods in its NSX racing V-6 engine; Titanium valve springs are used in high-capacity, four-cylinder engines made by Mitsubishi Motors and titanium connecting rods are used in Porsche cars.
(1) Valve
In terms of titanium valves, the United States and Japan have carried out a lot of research work. At present, the United States generally uses Ti-6Al-4V alloy to manufacture intake valves and Ti-6Al-2Sn-4Zr-2M o alloy to manufacture exhaust valves. While the Japanese Toyota company uses Ti-6Al-4v /Ti B alloy to prepare the intake valve and Ti-al-Zr-Sn-Mo-Nb-Si /Ti B alloy to prepare the exhaust valve. These titanium alloys have good high temperature mechanical properties, oxidation resistance and creep resistance, which effectively improve engine performance and vehicle speed.
(2) Valve seat
Titanium alloy valve seat has been widely used in racing cars and sports cars, more than 250,000 sets are produced annually, mainly using Ti-6Al-4V or Ti-5Al-2Cr-1Fe alloy preparation, because the shape of the valve seat is relatively simple, so the mechanical processing requirements are not high, and do not need special surface treatment, the cost is cheaper. In automobile weight reduction effect is obvious.
(3) Connecting rod
The use of titanium rod can effectively reduce the weight of the engine and improve the performance of the vehicle. At present, the main preparation material is Ti-6Al-4V alloy. A two-phase titanium alloy Ti-3Al-2V-0.2Si-0.47Ce-0.27La is currently being developed by Tatsu Co., LTD., which has excellent machinability, mechanical properties, fatigue properties and corrosion resistance, and is expected to be used in the connecting rod parts of engines with rapid acceleration and deceleration.
(4) Crankshaft
Although titanium crankshaft has not been widely used at present, but Japan specially developed Ti-3Al-2.5V alloy has been verified in Honda racing car above, effectively reduce the mass at the same time, the engine speed increased 700r/min, proving the superiority of titanium crankshaft. Meanwhile, Japan has been trial-producing Ti-5Al-2Cr-Fe alloy crankshaft, hoping that titanium alloy will be more widely used in crankshaft components.
3. Vibration reduction system
The core component of automobile damping suspension system is suspension spring. Compared with the general automobile spring steel, titanium alloy has higher specific strength and lower shear modulus, fatigue strength is also higher, more suitable for the manufacture of automobile vibration damping spring. Because the deflection of the spring is proportional to the number of turns, and the shear modulus of the material is inversely proportional, therefore, titanium alloy spring in the same spring reaction situation, than steel spring needs fewer turns, effectively reduce the spring mass, save space.
At the same time, titanium alloy spring can also effectively improve the resonance frequency of the spring, improve its service life. At present, most titanium alloy springs are prepared with single-phase β titanium alloy. Volkswagen has already used Lupo FSI titanium gear springs in some of its 3,500 vehicles.
4. Car frame
The high specific strength, low density and good corrosion resistance of titanium alloy indicate that it is a good material for the preparation of car body frame. At present, there are already automobile companies in the gear bracket, brake caliper piston and other components using titanium alloy. Among transmission components, Japan is currently developing a high spinning forming process to prepare a titanium alloy case, which can better mitigate the impact of the flywheel and have a better buffering effect compared to the steel case.
In addition, titanium alloy is also used in automotive fasteners and other components, with the continuous development of titanium alloy preparation technology and automotive industry, titanium alloy will be more and more applications in automotive parts.
5. The significance of titanium alloy for automobile lightweight
Foreign research institutions have estimated that when the quality of vehicle maintenance is reduced by 10%, fuel consumption can be reduced by 6%~8%. Another study found that a 91kg lighter car can drive 0.43 kilometers more per liter of fuel. Therefore, with the continuous development of our economy and the increasing number of vehicles, vehicle lightweight has become one of the important ways to reduce energy consumption and reduce air pollution.
Titanium and titanium alloys are widely used in automobile parts because of their excellent physical and chemical properties. The use of titanium material not only effectively improves the performance and safety factor of the automobile, but also plays an important role in the lightweight of the automobile, effectively reduces the quality of the automobile reconditioning, and reduces the fuel consumption.
Automotive exhaust system using titanium tail-nozzle and return pipe assembly, compared to the traditional stainless steel system, approximately 8.2kg weight reduction. The valve, connecting rod and other parts of the engine parts using titanium alloy products instead of traditional steel and cast iron materials can effectively reduce the engine mass.
According to the research of the Japanese automobile industry, the effect of using about 0.8kg titanium parts for the automobile power valve is equivalent to that of 20kg steel parts. Each titanium valve seat can reduce the mass of about 10g compared with steel valve seat; Connecting rods and crankshafts used in titanium alloy are most effective in reducing engine mass.
Vibration damping system above, each titanium alloy spring than steel spring to reduce more than 60% of the mass, to each car 4 spring calculation, after replacing titanium alloy spring, each car can reduce the weight of 9~13.6kg. In addition, titanium mufflers weigh only 5 to 6kg, which is 40 percent lighter than stainless steel mufflers.
Take ordinary medium-sized cars as an example, if the traditional parts are replaced with existing titanium alloy auto parts, the vehicle's reconditioning mass will be reduced from about 1500kg to about 1000kg, the weight reduction rate can reach 30%, and the comprehensive fuel consumption can be reduced by more than 20%, which will greatly reduce the fuel consumption of the world. Effectively alleviate the problems of energy shortage and environmental pollution.
The above data show that the use of titanium alloy in automobile lightweight effect is obvious, in the modern automobile industry, should continue to develop the application technology of titanium and titanium alloy in automobile parts, improve the application ratio of titanium alloy in automobiles.
At present, the application of titanium alloy in our automobile industry is still in the trial stage. The main problems are the high cost of titanium alloy materials, parts are not easy 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 other ways, and improve the processing efficiency of titanium alloy parts by improving processing technology.
Foreign experience shows that only the combination of automotive design and manufacturing and titanium alloy development can provide more high-quality titanium alloy materials for automobiles.
I believe that with the continuous development of research and development, titanium and titanium alloy will play a more and more important role in our modern automobile industry, to promote the continuous development of the automobile industry.
