Application and development of titanium material in automobile muffler
Pure titanium metal has the characteristics of low specific gravity, corrosion resistance and good plasticity, and has been used in the muffler of many high-end cars with large displacement. In a car, because the muffler is hidden in an invisible place, and there is no need to emphasize its sense of luxury and creativity, the temperature of the exhaust pipe is much higher than that of a locomotive. Under the environment of high temperature oxidation resistance and high temperature strength, it is undoubtedly pure Titanium is an excellent choice for special silencers. When the temperature of the exhaust pipe is too high, in order to avoid substantial damage to the plastic material of pure titanium, Ti-1.5Al titanium material with high temperature oxidation resistance and high temperature strength has been developed, which has increased the exhaust temperature to the current 700 ~750℃, widely used in car silencers.
As far as automobiles are concerned, for pure titanium materials, although the temperature of the exhaust pipe after the center pipe is relatively low, the exhaust temperature of this part can reach 700~800℃ due to different vehicle types. Titanium metal exposed to such high temperature for a long time, due to oxygen intrusion, the surface edge part will become weak due to the formation of a hardened layer. At the same time, the exfoliative oxidation ratio is generated, and the metal titanium part is reduced in meat, which will cause the strength to decrease. In addition, due to the coarsening of crystal grains, fatigue strength reduction and embrittlement occur. In a high temperature environment like this, Ti-1.5Al also cannot correspond to its oxidation resistance. Therefore, automobile manufacturers expect to be able to develop titanium materials that are more resistant to high temperature oxidation than Ti-1.5Al and retain the strength characteristics of Ti-1.5Al in the forming and processing of composite parts of the muffler system.
Ti-0.5A1-0.45Si-0.2Nb titanium alloy is considered the most promising alternative to Ti-1.5Al. Compared with the existing muffler material and pure titanium Ti-1.5Al, this titanium alloy has better high temperature oxidation resistance. This titanium alloy solves the concerns that it cannot be used in high temperature environments due to embrittlement and other problems. At the same time, the high temperature strength is close to that of Ti-1.5Al. Compared with Ti-1.5Al pure titanium at 400℃, the yield strength is 3 to 4 times that of pure titanium, and the tensile strength is 2 to 3 times that of pure titanium. Therefore, this titanium alloy has the same characteristics as Ti-1.5Al suitable for high temperature strength. Moreover, this titanium alloy has the same level of formability as Ti-1.5Al pure titanium.