Possibilities and limits in thermohydrogen processing of beta titanium alloy Timetal®10-2-3

Abstract The microstructure of the metastable -titanium alloy Timetal®10-2-3 was changed systematically by means of thermohydrogen processing, in order to improve the mechanical properties. The thermodynamic and kinetic data-base was determined experimentally and the change in the beta transus temperature was determined quantitatively. The results were used to design a 4-step heat treatment process involving hydrogen during the first two steps. A comparison of the fatigue properties of the standard heat-treated and the thermohydrogen-processed alloy revealed that, despite the increase of the monotonic strength of the thermohydrogen-treated alloy, the fatigue limit is slightly reduced, while the fatigue crack growth threshold remains almost unaffected. From this correlation a strategy can be deduced for a further improvement of the thermohydrogen-processing procedure, in order to tailor the fatigue properties according to the requirements of the respective application.