Due to the excellent properties of titanium, more and more occasions are used in automobiles, but the higher price hinders its application. The following focuses on the application status and recent trends of titanium in family automobiles, and introduces two applications that have become breakthroughs in expanding applications.
The excellent properties of titanium mainly refer to its high strength, low density and excellent corrosion resistance, which can be used in the power transmission and chassis of automobiles. These applications are mainly aimed at the fact that titanium is a lightweight alloy and can replace stainless steel. Reducing the weight of automobiles is expected to improve the performance of automobiles.
Weight reduction is very flexible for car design, which is very important for sports cars and family cars. So far, the manufacturers of sports car engines have chosen titanium as raw material in order to lighten the weight of valves and connecting axles for automobiles. The performance improvements are manifested in the reduction of rotation distance, output power and deformation of connecting parts.
The advantages of using titanium in automobiles are that the power transmission effect or weight reduction can save fuel, reduce engine noise and vibration, and reduce component load, which can improve the durability of automobiles. Titanium can be used as valves, connecting axles, valve springs and supporting devices in car parts.
Titanium uses in places other than engines: For example, if titanium is used in the chassis of a car, it can reduce the weight of the car and save fuel. Most notable are the use of titanium in suspension springs, exhaust devices, crankshafts and other fasteners. The biggest obstacle to the extensive use of titanium in sports cars and cars is still the price problem.
The world titanium market is about 45,000 mt/year, half of which is in the United States. The world’s total production of automobiles is about 60 million units per year, with the United States accounting for 1/4 of that. Therefore, if half of the world’s automobiles are made of titanium, the consumption of titanium can be increased by another 30% based on the consumption of about 500 g per unit of titanium. In this way, the amount of titanium used in automobiles is considerable.
Application of Titanium in Home Cars
Timet, the largest titanium manufacturer in the United States, lists the advantages of using titanium as a component in automobiles as follows:
(1) The use of titanium solves some practical problems.
(2) Coordination with the market;
(3) Relevant technology of titanium material application exists.
(4) The established technology can be utilized;
(5) The use of titanium material has new value.
Titanium was first used in the mass-produced NSX V-6, a premium car, and then in the valves of Toyota’s two-door convertible car, which won an award in Japan in 1998. Ti-6Al-4V/TiB alloy produced by powder metallurgy was used in the intake valve and Ti-Al-Zr-Sn-Nb-Mo-Si/TiB alloy with heat resistance was used in the exhaust valve. The engine of the car is 2000 cc. It uses one 27g intake valve and eight 24g exhaust valves. The total titanium material used in a car is 408 G. When the raw material is steel, their respective weights are 40.0g and 44.6g, and the total weight of the valve is more than twice that of the titanium material. Titanium is also used in the valve springs of the car, and its weight is reduced from 43 g to 36 G. Toyota initially produced 4,000 of the new cars, half of which were made of titanium.
In addition, examples of other Japanese companies using titanium are Honda S2000 and R models. Titanium is also used in mass-produced connecting axles on some cars in Europe.
Titanium for family cars has recently been used in 2 cases. For example, in the case of exhaust valve of GM Chevrolet Z06, the reduction of total weight is beneficial to the improvement of performance. The weight of two titanium silencers and one group of silencers is 11.7g, and the weight is reduced by 41%, which is helpful to improve the performance of the car. And the life of the muffler is semi-permanent.
Timet and Arvin Meritor have jointly developed a new Timetal exhaust grade titanium alloy (the same as Ti2 grade) based on the market and existing technology. The material was tested by the two companies in accordance with the contract and its performance was confirmed. During the test, the punching, bending, cold rolling and welding technologies established for stainless steel will be improved so as to be applied to titanium flexibly and achieve the purpose of reducing weight.
Compared with steel, titanium metal has low modulus of elasticity and low density, which is suitable for spring. Titanium springs are widely used in the aerospace industry dominated by Boeing, but Timet believes that these components are too expensive to be used in automobiles. Therefore, the company jointly developed titanium springs for automobiles with aerospace component manufacturers, and received strong support from German VW company. Timet and VW are both automotive parts manufacturers, using standard steel spring production equipment to produce titanium springs. Muhrund Bender, a component manufacturer chosen by VW, has transformed its steel spring manufacturing equipment to produce titanium springs. As a result, the cost of using low-cost beta-alloy Ti-4.5Fe-6.8Mo-1.5Al is 50% lower than that of existing beta-alloy. The weight of the spring made of this material is 1/3 less than that of the same steel spring, and it has the best fatigue life. The 2001 Lupo FSI car with this titanium spring is 81.6 kg lighter than the standard FSI. The Lupo FSI is the world’s lowest fuel-charged car at 48 mpg (mile/gallon) and is sold in the European market. VW’s annual production of this type of vehicle in 2001 is 3500 units.
Future Prospects
Titanium material is widely used in the automobile’s beginning. Titanium is used in special parts. Of course, the car body steel plate can not be replaced by titanium plate whose price is 50-100 times higher than that of the car body steel plate. The use of the special parts developed is expanded by the development of design and production technology in the future, and new special uses can be considered. The problem to be solved is to transfer the use of titanium components from special state to mass production by reducing costs. It is hopeful to get cheap titanium sponge, but it is unlikely to be achieved by drastically improving Crowl or Hunter processes. Fray’s law is currently in the experimental stage and is likely to be a promising new technology. At present, powder metallurgy technology and primary melting technology (cold furnace EB melting or plasma technology, etc.) are expected to reduce the cost of titanium products. Titanium manufacturers and users may also reduce costs if they sign long-term price contracts. The stable supply and quality assurance of titanium materials for automobiles are also crucial by making the best use of large-scale equipment for iron and steel production.