Expanded Titanium Applications- Some parts of automobiles can be made of titanium alloy

      The development of automotive titanium materials

      Titanium materials in the application of cars began in the middle of the 1950s. The United States General Motors launched a named “Firebird Ⅱ” titanium body exhibition car in 1956. In the late 1960s, Nissan used some titanium alloy parts in its R382 car. In the 1980s Honda used titanium to make racing car parts.

      Fig 1 Overview of automotive titanium structural parts

      Note: source: China Titanium Industry Association.

      Since the 1990s, due to technological progress, some low-cost titanium alloys have been developed, such as Time-62S, Timetal-LCB, Timetal-1100 and SP-700 from American Titanium Metal Company. At the same Time, due to the urgency of energy conservation and emission reduction and the increasing requirements for improving performance, Interest in the use of titanium in automobiles is growing even further. In 1992, the 29th International Motor Show in Tokyo exhibited cars with titanium bodies and engines made in Japan; In 1996, the Titanium Exhausting System developed by the American Titanium Metal Company (TIMET) was presented at the National Association Conference, followed by a Titanium Exhausting System manufactured by Chrysler. 1989-1998 Japanese automobile titanium 669 t. Titanium has also built a factory to produce titanium alloy parts for cars.

      Using titanium alloy to manufacture automobile valves can not only reduce quality, prolong service life, but also improve reliability and save fuel. Early use of a costly titanium alloy, and later the use of γ-Ti Al alloy, the engine Max speed increased by about 10%. In recent years, some titanium manufacturers have developed a number of cheaper titanium alloys for engine valves, and some of them have entered the mass production stage. It is a key technology to improve the wear resistance of titanium alloy used in valve. It is one of the effective processes to improve the surface hardness and wear resistance to oxidize the surface even if the solid solution in titanium is as much oxygen as possible. The V-8 cylinder made by Del West Company in the United States has been widely used for inlet and exhaust valves. Ti-6Al-4V is used for inlet valves and Ti-6Al-2Sn-4Zr-2Mo alloy is used for exhaust valves. The weight of each valve is about 50g lighter than that of stainless steel, and the service life is extended by 2 to 3 times. The Ti-5Al-2Cr-1Fe alloy intake valve prepared by Hitachi has been widely used. The R382 and R380 racing cars of Nissan Motor Company equipped with this kind of intake valve have achieved excellent results in many races. The mass of steel valve used in the past is 90g, while that of titanium alloy valve is only 55g, which is reduced by about 40% and the performance is improved by 10% ~ 15%.

      In 1998, the Toyota Motor Company’s two-door sedan and Honda Motor Company’s Altezza used powder metallurgy Ti-6Al-4V/TiB alloy intake valve, exhaust valve is made of heat-resistant Ti-Al-Sn-Zr-Mo-Nb-Si/ Tib alloy. The former engine displacement of 2 000 ml, equipped with a 27 g intake valve and 8 24 g exhaust valve, a car with a total of titanium 408 g, the car’s valve spring is also made of titanium alloy, its mass decreased from 43 g to 36 g, going down by 16.3%.

      The exhaust valve has high working temperature and can be made of high temperature titanium alloy Ti-6Al-2Sn-4Zr-2Mo-0.1Si (6242S). But the motorcycle valve is more likely to be exposed to high temperature for a long time, so it is appropriate to choose the more heat-resistant TIMETAL-1100 (Ti-2.7Sn-4Zr-0.4Mo-0.45Si) alloy, it is one of the best heat-resistant titanium alloy, the working temperature is about 600℃, The exhaust valve of two wheels motorcycle is best made of titanium alloy which can work for a long time at 800℃. At the same time, the alloy should have high damage resistance and tolerance, so researchers hope to develop AlTi3 and AITI based intermetallic compound new titanium alloy, and achieved certain results, the representative alloy is: Ti-14Al-21Nb, Ti-14Al-21Nb-3V-2Mo, Ti-24Al-10Nb, Ti-25Al-8Nb-2Mo-2TA, Ti-25Al-10Nb-3V-1Mo, and Ti-22AI-27Nb, but they’re not cheap.

      The 746-kW V-16 engine of the General Motors Cadillac Model 16 uses a wide range of light metals. The cylinder body and cylinder head are made of aluminum alloy, while the valve springs and some parts are made of titanium alloy. It has a fuel economy of 7.23 km/L.