DUSTI

In order to meet the requirements of economic and ecological performances from airline companies and civil society in general, engine manufacturers propose to resort to more powerful engines showing higher by-pass ratios. This impacts the pylon directly. Indeed, to increase the by-pass ratio implies that the external diameter of the nacelle increases, thus reducing space between the engine and the wing. The design of pylons manufactured by the Airbus St Éloi plant thus evolve to a greater compactness and thus potentially to higher temperatures views in service which ask the question of the use of TA6V titanium alloy with regard to oxidation, ageing and mechanical properties in temperature. On the other hand, the wish of mass reduction of the old and future pylons by the replacement of Nickel alloy used today, of which the density is double, duct Airbus to be in titanium alloys presenting good mechanical properties at ambient temperature but also in temperature (good intrinsic characteristics and thermal stability). The same challenges of mass reduction and rise of the operating temperatures caused by the increased performances of the engines are encountered by the materials used in the air systems produced by Liebherr. Indeed, these aeronautical air systems make it possible to condition the air taken at compressing stages of the engines to bring it to comfortable pressure and temperature levels for the passengers. Thus the use of light materials offering of high temperature resistance becomes essential. Titanium alloys seem to be the best candidates for these applications by their low density and their heat resistance. The matter of the project DUSTI is, upstream, to have a better understanding of metallurgical phenomena which act in various studied alloys (TA6V, Ti17, Ti6242) related to the environment and in service solicitation: - oxidation and link with fatigue properties, - metallurgical mechanisms of ageing in titanium alloys and induced amendments of the oxidation kinetic and mechanical properties, - damage mechanisms in titanium alloys in temperature, - fatigue crack propagation behavior of titanium alloys at high temperature, in link with the environment. Indeed, these mechanisms are likely to harm the integrity of the structures and aeronautical components made in titanium, as they involve a modification of the dimensioning properties. This project thus implies at the sides of the final users, the specialists in the transformation and the metallurgy of titanium alloys, the oxidation mechanisms and the damage mechanisms in severe environment. EADS IW, AIRBUS, LIERBHERR and AUBERT&DUVAL thus unite their forces with those of the Institute Jean LAMOUR, the Institute P' and the CIRIMAT.