[Expanding the application of titanium]Some parts of automobiles can be made of titanium alloy (1)

Automotive structural parts that can be made of titanium alloy are mainly engine system valves, springs and their bearings, connecting rods, crankshafts, gearboxes, steering racks and pinions, etc., chassis system springs, mufflers, exhaust devices, etc. Body system wheel bushings and bearings, various axle shafts, fasteners, etc. Racing parts have been made of titanium in large quantities, because racing is cost-free, and the pursuit of victory and safety.

The development history of automotive titanium

The application of titanium in automobiles began in the last century50In the middle of the decade,1956General Motors of the United States launched a titanium body exhibition vehicle named “Firebird II”.Nissan Motor Company of Japan20century60In production in the late decadeR382Some titanium alloy parts were used in the car; last century80The Honda Motor Company used titanium to manufacture racing parts.

last century90Since the 1980s, some low-cost titanium alloys have been developed due to technological advances, such as the American Titanium Metal Company’sTime-62S,Timetal-LCB,Timetal-1100,SP-700At the same time, due to the urgency of energy saving and emission reduction and the increasing requirements for improving performance, people’s interest in the application of titanium in automobiles has further increased.1992Held in Tokyo in the year29Japanese-made cars with titanium bodies and engines were exhibited at the International Automobile Exhibition;1996In the year, the American Titanium Metals Corporation (Timet) The titanium exhaust system developed was exhibited at the National Association meeting, and then Chrysler Automobiles manufactured a titanium alloy exhaust system.1989year~1998Titanium for Japanese Automobiles669t. Titanium Metals has also built a factory specializing in the production of automotive titanium alloy parts.

The use of titanium alloy to manufacture automotive valves can not only reduce the quality, extend the service life, but also improve the reliability and save fuel.Earlier used titanium alloys with high manufacturing costs, and then usedγ-Ti AlAlloy, engineMaxSpeed ​​increased by approx.10%. In recent years, some titanium producers have developed a batch of lower-priced titanium alloys for engine valves, and some of them have entered the mass production stage. Improving the wear resistance of titanium alloys for valves is a key technology. Oxygen permeation treatment on the surface, even if there is as much oxygen as possible in the titanium solid solution, is one of the effective processes to improve the surface hardness and wear resistance.

American Del·West (Del west) Made by the companyV-8The intake and exhaust valves of the cylinder block have been widely used, and the intake valve isTi-6Al-4V, The exhaust valve used isTi-6Al-2Sn-4Zr-2Moalloy.The mass of each valve is approximately lighter than stainless steel50g, And the expiration date has been extended2~3Times.Prepared by Hitachi, Japan by sintering methodTi-5Al-2Cr-1FeAlloy intake valves have been widely used. The Nissan Motor Co., Ltd. equipped with this intake valveR382AndR380The car has achieved excellent results in many races.The quality of the steel valve used in the past is90g, While the titanium alloy valve only55g, Relieved about40%, Performance improved10%~15%.

1998In the year, Japan’s Toyota Motor Corporation’s two-door convertible sedan and Honda Motor Corporation’s Altza (Altezza) All cars use powder metallurgyTi-6Al-4V/TiBAlloy intake valve and exhaust valve are heat-resistantTi-Al-Sn-Zr-Mo-Nb-Si/TiBAlloy, the former’s engine displacement is2000ml, With1indivual27gThe intake valve and8indivual24gOf exhaust valves, a total of titanium used in a car408g, The valve spring of this car is also made of titanium alloy, and its quality is from43gFall to36g,Reduced16.3%.

The working temperature of the exhaust valve is high, and high temperature titanium alloy can be usedTi-6Al-2Sn-4Zr-2Mo-0.1Si(6242S) Alloy build.But motorcycle valves are more likely to be exposed to high temperature areas for a longer time, so it is better to choose more heat-resistantTimetal-1100(Ti-2.7Sn-4Zr-0.4Mo-0.45Si) Alloy, it is one of the best heat-resistant titanium alloys, the working temperature is about600℃, and the two-wheeled motorcycle exhaust valve is best800℃ made of titanium alloy for long-term work.At the same time, the alloy should have high damage tolerance performance, so researchers hope to developAlTi3withAITiA new type of titanium alloy based on intermetallic compounds, and has achieved certain results. The representative alloys are:Ti-14Al-21Nb,Ti-14Al-21Nb-3V-2Mo,Ti-24Al-10Nb,Ti-25Al-8Nb-2Mo-2Ta,Ti-25Al-10Nb-3V-1MowithTi-22AI-27Nb, But they are expensive.

Cadillac16Car746kW V-16The engine widely uses light metal materials, the cylinder block and cylinder head are made of Aluminum alloy, and the valve spring and some accessories are made of titanium alloy.Its fuel economy is up to7.23km/L.