Application of Titanium Alloy in Automobile Lightweight Manufacturing

Titanium and titanium alloys have the characteristics of low density, excellent mechanical properties, good biocompatibility, corrosion resistance, high temperature resistance, and good low temperature toughness. At present, they have been widely used in automobile manufacturing. The density of titanium alloy is only 60% of that of steel, and the strength can reach more than 800MPa. It still maintains good mechanical properties at about 500°C, and its welding and forming properties are good. It has been used in the manufacture of racing cars more than 20 years ago. Significantly reduce the quality of the racing engine, while improving the engine performance.

At present, titanium alloy components used in automobile manufacturing are mainly distributed in automobile exhaust systems, engine systems, transmission and vibration reduction systems, and car body frame parts.

1. Exhaust system

Automobile exhaust system materials are required to have good high-temperature mechanical properties and resistance to S and Cl element corrosion. Traditional exhaust valve components are made of stainless steel, but it has been found that titanium alloys are more suitable for exhaust valve materials in terms of performance.

The titanium return pipe used in the new Chevrolet Corvette Z206 car effectively avoids the pitting corrosion and weld corrosion on the stainless steel pipe, while also improving the fuel combustion efficiency and acceleration ability, and shortening the braking distance .

Timet, the largest titanium manufacturer in the United States, has been committed to the research and development and manufacture of titanium alloy exhaust systems, and many Japanese companies have also carried out related research and development work. At present, Fuji Heavy Industries Co., Ltd. has produced a limited number of 440 sets of titanium alloy vehicle exhaust systems. trachea.

2. Engine System

Automobile engine system is the most used part of titanium alloy in the automobile field. The application of titanium alloy in engine system mainly includes valve, connecting rod, crankshaft, valve seat and other parts.

Japan's Honda Motor Company uses forged titanium connecting rods in the NSX racing V-6 engine; Mitsubishi Motors uses titanium valve spring seats in high-capacity, four-cylinder engines, and Porsche cars also use titanium connecting rods.

(1) Valve

In terms of titanium alloy valves, the United States and Japan have conducted a lot of research work. At present, the United States generally uses Ti-6Al-4V alloy to make intake valves and Ti-6Al-2Sn-4Zr-2M o alloy to make exhaust valves; while in Japan Toyota uses Ti-6Al-4V/Ti B alloy for the intake valve and Ti-Al-Zr-Sn-Mo-Nb-Si/Ti B alloy for the exhaust valve. These types of titanium alloys all have good high-temperature mechanical properties, oxidation resistance and creep resistance, which effectively improve engine performance and speed up vehicles.

(2) Valve seat

Titanium alloy valve seats have been widely used in racing and sports cars. More than 250,000 sets are produced every year. They are mainly made of Ti-6Al-4V or Ti-5Al-2Cr-1Fe alloy. Because the shape of the valve seat is relatively simple, it is used in The machining requirements are not high, and no special surface treatment is required, the cost is relatively cheap, and the effect is obvious in reducing the weight of the car.

(3) Connecting rod

The use of titanium alloy connecting rods can effectively reduce the quality of the engine and improve the performance of the car. At present, the main preparation material is Ti-6Al-4V alloy. Japan Daido Co., Ltd. is currently developing a two-phase titanium alloy Ti-3Al-2V-0.2Si-0.47Ce-0.27La, which has good machinability and excellent mechanical properties, fatigue properties and corrosion resistance. , It is expected to be used in the connecting rod parts of the engine that accelerate and decelerate rapidly.

(4) Crankshaft

Although titanium alloy crankshafts have not been widely used at present, the Ti-3Al-2.5V alloy specially developed by Japan has been verified on Honda racing cars. While effectively reducing the quality, the engine speed has been increased by 700r/min, which proves that titanium The superiority of alloy crankshaft. At the same time, Japan has trial-produced Ti-5Al-2Cr-Fe alloy crankshafts, and it is expected that titanium alloys will be more widely used in crankshaft components.

3. Damping system

The core component of the automobile damping suspension system is the suspension spring. Compared with general automobile spring steel, titanium alloy has higher specific strength and lower shear modulus, and higher fatigue strength, making it more suitable for the manufacture of automobile damping springs. Since the deflection of the spring is directly proportional to the number of turns and inversely proportional to the shear modulus of the material, the titanium alloy spring requires fewer turns than a steel spring under the condition of achieving the same spring response, which effectively reduces the spring quality. , Save space.

At the same time, the titanium alloy spring can also effectively increase the resonance frequency of the spring and increase its service life. At present, most of the titanium alloy springs are made of single-phase β titanium alloy. The German Volkswagen Company has used Lupo FSI titanium alloy gear springs in some cars, and the amount is about 3,500.

4. Body frame

In terms of car body frame components, the higher specific strength, lower density and good corrosion resistance of titanium alloy indicate that it is a good material for preparing car body frames. At present, some automobile companies have used titanium alloys on parts such as gear brackets and brake caliper pistons. Among the transmission components, Japan is currently developing a high-spinning process for preparing titanium alloy casings. Compared with steel casings, titanium alloy casings can better reduce the impact of the flywheel and have a better cushioning effect.

In addition, titanium alloys have also been used in automotive fasteners and other components. With the continuous development of titanium alloy preparation technology and the automotive industry, titanium alloys will surely be more widely used in automotive parts.

5. The significance of titanium alloys to the lightweight of automobiles

Foreign research institutions have calculated and found that when the quality of a car's servicing drops by 10%, the fuel consumption can be reduced by 6% to 8%. Studies have also shown that for every 91kg of weight loss, an average of 0.43km per liter of fuel can be traveled. Therefore, with the continuous development of my country's economy and the continuous increase in the number of cars, the lightweight of cars 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 auto parts due to their excellent physical and chemical properties. The use of titanium materials not only effectively improves the performance and safety factor of the car, but also plays an important role in the lightweight of the car, effectively reducing the quality of the car's servicing and reducing fuel consumption.

Compared with the traditional stainless steel system, the titanium exhaust nozzle-return pipe assembly is used in the automobile exhaust system, which can reduce the weight by about 8.2kg. The use of titanium alloy products to replace traditional steel and cast iron materials in engine parts such as valves and connecting rods can effectively reduce the quality of the engine.

According to the research of the Japanese automobile industry, the use of about 0.8kg of titanium material for automotive power valves is equivalent to the effect of 20kg of steel parts; each titanium valve seat can reduce the weight of about 10g compared to steel valve seat; even Rods and crankshafts are used in titanium alloys, which are the most effective for reducing engine mass.

On the vibration damping system, each titanium alloy spring can reduce the mass by more than 60% compared with steel springs. Based on 4 suspension springs per vehicle, after changing to titanium alloy springs, each vehicle can reduce weight by 9~13.6kg. 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 the existing titanium alloy car parts are used to replace the traditional parts, the car's curb weight will be reduced from about 1500kg to about 1000kg, the weight reduction rate can reach 30%, and the overall fuel consumption can be reduced by 20%. Above, this will greatly reduce the fuel consumption of the world, and effectively alleviate the problems of energy shortage and environmental pollution.

The above data shows that the use of titanium alloys has a significant effect in reducing the weight of 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 in automobiles.

At present, the application of titanium alloy in my country's automobile industry is still in the trial stage. The main problem is that the cost of titanium alloy materials is too high, and the 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 has shown that only the combination of automobile design and manufacture and titanium alloy research and development can provide higher quality titanium alloy materials for automobiles.

It is believed that with the continuous deepening of research and development, titanium and titanium alloys will play an increasingly important role in my country's modern automobile industry and promote the continuous development of the automobile industry.

Nicole