Kasatori, S., Marui, Y., Oyama, H., and Ono, K., "Development of Heat Resistant Titanium Alloy for Exhaust Valves Applicable for Motorcycles," SAE Int. J. Mater. Manf. 10(1):43-51, 2017, doi:10.4271/2016-32-0023.
Amidst of the recent concerns on depletion of natural resources, a new heat resistant titanium alloy has been developed using the minimum amount of rare metals. Using Ti-811 as a basis and modifying the alloy composition to Ti-7Al-2Mo-0.2Si-0.15C-0.2Nb, the mechanical property, the creep resistance and the oxidation resistance at high temperatures are improved. At the same time, with the β transformation point shifted to a higher temperature, the hot formability is also improved. The newly developed alloy has made it possible to expand the application of titanium material to exhaust valves in reciprocating engines.