Status And Prospects Of Titanium And Titanium Alloys For Automobiles

It now seems that automobiles have been an indispensable means of transportation in our lives for more than 100 years. Titanium's properties such as light weight and high strength have long been the focus of automakers.

Titanium has been used in automobiles for many years now, and cars are almost all used up this year. However, it is the importance of the cost of the average automobile to the use of titanium that will be the subject of the future. Automobiles (including motorcycles and discount cars) are an emerging market for titanium.

Advantages of using titanium as a material for automotive parts: high strength, low density, modulus of elasticity about half that of steel, low coefficient of thermal expansion, about half that of stainless steel and aluminum, non-magnetic, low thermal conductivity, and non-polluting to the environment. In addition, the use of titanium in the automobile industry can greatly reduce the weight of the car, reduce its fuel consumption, improve the efficiency of the car and reduce noise. According to the data show that every 10% reduction in the weight of the car body, you can reduce 10% of exhaust emissions, and save 7% of fuel consumption, so automotive lightweighting will play a "energy saving, environmental protection," the effect of two birds with one stone. Titanium is the most ideal metal to achieve weight loss.

1 titanium alloy in automobile applications

Titanium alloy auto parts are mainly: made of TiAl turbine rotor blades, with Ti-6Al-4V alloy and other connecting rods, valves and so on. In order to achieve low cost, the use of powder metallurgy method to add titanium alloy. TiB particles were dispersed titanium-based MMC in Ti-6Al-4Sn-4Zr-1Nb-1Mo-0.2Si-0.3C alloy matrix, and the material was used to manufacture engine valves.

This is an example of the application of the material as a new titanium-based material for automobile engine valves. In addition to connecting rods and engine valves, the original low-cost β-titanium alloy LCB TIMETAL was used to manufacture suspension springs for the first time. Recent progress in the development of low-cost titanium alloys for engine valves and exhaust valves. In particular, the demand for titanium alloys for motorcycle exhaust systems (silencers) has increased, so exhaust systems have become more popular with the development of low-cost alloys...

1.1 Valves

The production of automobile valves from titanium alloys not only reduces weight, extends service life and is highly reliable, but also saves fuel. Exhaust valves are required to contain lead and cobalt in addition to heat and wear resistance. U.S. manufacturers use titanium alloys, exhaust valves are more common, intake valves are made of Ti-6Al-4V alloy, while exhaust valves are made of Ti-6Al-2Sn-4Zn-2Mo alloy. Sintered intake valves produced by Hitachi in Japan have been supplied to the Japanese automotive industry market.

Howmet Foundry in the U.S. uses continuous casting methods to produce valves, each valve has 1/4 weight of titanium, and it is expected that 200 million new cars are placed on the potential market each year, and there is a valve replacement market of 80 million.

1.2 Valve Seats

The most widely used titanium component in motor vehicles and motorized vehicles is the valve seat, with an annual production of more than 250,000 units, which is generally produced in Ti-6Al-4V alloy, and also in Japan in Ti-5Al-2Cr-1Fe alloy. Because of the simple shape and small size, there are mechanical additions that are easy to make and relatively inexpensive. Do not necessarily need special surface treatment, steel valve seat can be reduced by 10 to 12.

1.3 Titanium connecting rod

Connecting rod using titanium alloy to reduce the weight of the engine is the most effective, can greatly improve performance. The connecting rod material is mainly Ti-6Al-4V, other such as Ti-7Al-4Mo, Ti-4Al-2Sn-4Mn, etc. are also under development.

1.4 Crankshaft and other engine parts

Ti-5Al-2Cr-Fe alloy crankshafts are being trial produced in Japan, and this curve is not yet practical due to the need for anti-sticking treatment. Other engine parts such as rocker arms, valve springs, lower bolt connecting rod can also be made of Ti-6Al-4V alloy.

Japan's specially developed easy-to-cut Ti-3Al-2.5V alloy crankshaft has been used in Honda 280 hp 3.0-liter V6NSX-type limousine, and with the steel crankshaft has the same fatigue strength, weight reduction of 30%, the engine speed increased by 700R /. The application of these research results shows that titanium has been accepted and expanded for use in automobiles.

1.5 Return air duct

The use of titanium alloy nozzle / return air pipe assembly is not subject to corrosion caused by sulfur chloride and exhaust gas emissions, the exhaust system does not pitting, even in the welding is not corrosive, compared with the traditional exhaust system materials and stainless steel can be reduced by 40% to reduce the weight of the material and to improve fuel economy, accelerate faster, shorter braking distance. Due to the high cost of titanium, Titanium Metals Corporation of America (Timet) has developed a special surface treatment that enables the production of parts that help meet the cost standards of automakers. Titanium tubing has been applied to the new Chevrolet Corvette Z06 sedan.

1.6 Suspension Springs

Compared to steel springs used in general purpose vehicles, titanium springs offer the advantages of light weight, corrosion resistance, and low shear modulus.Timet was designed to meet the cost and part assembly requirements of automotive suspension spring manufacturers by retaining the excellent properties of aerospace titanium alloy springs at a significantly reduced cost. Initial production quantities were small for the new FSI Lupo geared suspension springs from Volkswagen Europe.Timet and Volkswagen announced in January 2001 the introduction of titanium suspension springs in the FSI Lupo 2001 vehicle, of which a production run of 3,500 is expected.

Springs made from titanium can reduce the weight of steel by 70 to 60 percent. In a typical U.S.-made family car of six to five vehicles, weight savings of 9kg to 13.6kg per vehicle can be achieved through the use of four suspension springs.

The titanium 1.7 muffler muffler weighs only 5 to 6kg, much less than a stainless steel muffler, and is simple to operate. The demand for titanium in the Japanese automobile field (the actual demand in 1999 was 457t) is basically for mufflers, which are mainly used in large automobiles (over 900cc). Japan's four major manufacturers, including Honda and Suzuki, have adopted titanium alloy silencers. Titanium is mainly used for large automobile silencers and individual medium-sized cars. It is the evaluation of titanium's corrosion resistance, strength and surface design, etc..