Influence of the structure on the mechanical properties, the tenacity and the fatigue behaviour of the T-A6V titanium alloy

The propagation rate of fatigue cracks is an essential aspect in spacecraft safety. The 'Fissad' machine manufactured by the Company Aubert and Duval (France), which stems from the conventional 'Manlab's' machine, enables fatigue tests on Charpy V test specimens (10x10X55 mm) to be made. The advantage of such tests carried out on reduced size test specimens is a simple as well as a cheap way of plotting the fatigue-initiation curve and also the follow-up of the propagation rate. The results are compared of conventional fatigue tests under constant load with those obtained by means of the 'Fissad' machine, which stresses the test specimen under a constant distortion. With the T-A6V titanium alloy, the effect of forging conditions (β or α + β) and thermal treatments on the tensile conventional mechanical characteristics, the intensity factor of critical strain (Ksub(1C) and the fatigue behaviour has been investigated. (Auth.)