In the automotive sector, where silencers are hidden from view and where the sense and creativity of the silencer cannot be emphasised, exhaust temperatures are even higher than those of motorbikes. Titanium alloys and rods are used in silencers because of their excellent lightness, corrosion resistance and formability, as well as their sensitivity and creativity. In response to this situation, a number of companies have developed Ti-1.5Al, which improves resistance to high temperature oxidation and high temperature strength, in order to avoid significant damage to the formability of titanium alloy tubes and rods, and is used in silencers for automobiles because the exhaust temperature has been increased from the previous high to 700-750°C for reasons such as engine and catalyst conversion. In 2009, the product was registered in ASTM standards and was also licensed in the USA, UK, Germany, Italy and France.　　

Titanium alloy tubes and rods are considered to be more promising. These titanium alloys and rods have better resistance to high temperature oxidation than existing silencer materials such as JIS 2 pure titanium and Ti-1.5Al, which 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, and compared to JIS 2 pure titanium at 400°C, the buckling 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 and titanium rod have the same characteristics as Ti-1.5Al for high temperature strength. Furthermore, the alloy can be expected to have the same level of formability as JIS 2 pure titanium.

　　In the case of automobiles, the section after the centre tube has a lower temperature, but even the exhaust temperature in this section can reach 700-800°C depending on the type of vehicle. When titanium is exposed to such high temperatures for a long time, the surface edges become weaker due to the formation of a hardened layer, depending on the diffusion of oxygen. At the same time, a peeling oxidation ratio is generated and the titanium part reacts, thus reducing its strength. In addition, fatigue strength is reduced and embrittlement occurs due to the coarsening of the crystalline grains. Ti-1.5Al is also unable to cope with its oxidation resistance in such high temperature environments. Therefore, it would be a good material for silencers if a titanium material could be developed that retains the high-temperature oxidation resistance of Ti-1.5Al or more, and retains the strength properties of Ti-1.5Al for the forming and processing of assembled parts of silencer systems.