Garud, V. and Arankalle, A., "Titanium - A Futuristic Material for Vehicle Exhaust System and Powertrain Components," SAE Technical Paper 2014-28-0043, 2014, doi:10.4271/2014-28-0043.
India is blessed with considerable quantity of titanium based mineral resources accounting to about 20% of the world's availability holding and third largest reserves. The main titanium minerals are ilmenite and rutile available in beach sand deposits in the coastal states like Kerala with production of about 0.6 MT by mining & mineral separation process to provide environmental friendly titanium alloys. Though the major usage of titanium alloys are for aeronautics, defense, space, atomic energy sectors, its usefulness with special properties is yet to be exploited for the Indian automotive sectors. The principle advantages of Titanium alloys for automotive application that can be exploited are - 45% lighter than steel, virtually total resistant to acidic attack, four times more corrosion resistance than stainless steel, high specific strength, good ductility and ease to form by forging and machining operations. However at present, cost of extraction, alloying with other metals, casting and metal forming processes makes it difficult to penetrate in automotive industry. The R & D efforts are essential between academia, research institutes, and industry to make effective utilization of titanium alloys for motorcycles and four wheelers in the country in the future. The paper discusses the possible main application for vehicle exhaust system and powertrain to meet future emission Euro V & above requirement along with its importance as eco-friendly material and 50% lightweight structure to improve fuel economy. The titanium finds application because in Euro V, to meet NOx level of 0.27g/kWh will require EGR rates of 35% at full load and 50% at partial load and for these EGR rates, the compressed air pressure at the outlet is too high for standard materials for high temperature turbo compressor. In addition, the titanium dioxide coatings help to break down high mass flow that is required in commercial applications. It not only accelerates the hydrolysis of HNCO, but also catalyzes urea thermolysis. This approach of use of advanced titanium material will reliably will prevent the formation of solid urea decomposition products in exhaust gas systems. Finite element analysis of connecting rod shows optimization in 1.2% stress and 41.4% weight reduction when using Ti-6Al-4V alloy instead of C-70 splitable steel. The technical paper also discusses possible future potential applications in powertrain compartment, if through R & D efforts cost of material and process is reduced to competitive levels, then it can be used for components like connecting rod, piston assemblies, valves and valve springs, turbocharged wheel, suspension spring, brake line sealing, etc.