In terms of automobiles, due to the fact that the muffler is hidden in an invisible place, coupled with the inability to emphasize its advanced and creative nature, the exhaust temperature is higher than that of locomotives. Due to the issues of high-temperature oxidation resistance and high-temperature strength, titanium alloy pipes and rods are limited in their application in special silencers. Titanium alloys and rods have excellent lightweight, corrosion resistance, formability, and other characteristics, as well as a sense of sophistication and creativity, and are used in silencers. In response to similar situations, some companies have developed Ti-1.5Al to improve high-temperature oxidation resistance and high-temperature strength in order to avoid significant damage to the formability of titanium alloy pipes and rods. Titanium metal was developed based on reasons such as engine and catalyst conversion, which increased the exhaust temperature from the previous height to 700-750 ℃, and was therefore adopted in automotive silencers. In 2009, while logging into ASTM specifications, it also obtained licenses from the United States, the United Kingdom, Germany, Italy, and France.
Titanium alloy pipes and rods are considered more promising. This titanium alloy and titanium rod have better high-temperature oxidation resistance compared to existing muffler materials, JIS 2 pure titanium and Ti-1.5Al. Due to embrittlement and other issues, these existing materials cannot be used and the possibility of being used in high-temperature environments is considered. At the same time, the high-temperature strength is close to Ti-1.5Al, and compared with JIS two pure titanium at 400 ℃, the yield strength is 3-4 times that of pure titanium, and the tensile strength is 2-3 times that of pure titanium. Therefore, this titanium alloy and titanium rod have the same characteristics of suitable high-temperature strength as Ti-1.5Al. Moreover, it can be expected that this alloy has the same level of formability as JIS 2 pure titanium.
For cars, there is a relatively low temperature in the area behind the central pipe, but even the exhaust temperature in this area can reach 700-800 ℃ depending on the vehicle type. When titanium metal is exposed to this high temperature for a long time, the surface edges will become fragile due to the formation of a hardened layer due to the diffusion and invasion of oxygen. At the same time, the proportion of exfoliative oxidation occurs, and the titanium metal reacts, which will reduce its strength. Moreover, fatigue strength reduction and embrittlement occur due to coarsening of crystalline particles. In high-temperature environments like this, there are also areas where Ti-1.5Al cannot correspond to its oxidation resistance. Therefore, if a titanium material with a high temperature oxidation resistance of Ti-1.5Al or above can be developed, and a strength characteristic of Ti-1.5Al or above can be maintained in the forming and processing of composite parts of the muffler system, it will be a good muffler material.
