Thèse de doctorat en Métallurgie
Sous la direction de Richard Penelle.
Soutenue en 1986
à Paris 11 , en partenariat avec Université de Paris-Sud. Faculté des Sciences d'Orsay (Essonne) (autre partenaire) .
Le président du jury était Jean Philibert.
Contribution to the study of shear bands in some aluminium alloys
The aim of this work was to study the formation of shear bands (S. B. ) in plane compression test of three alloys of Aluminum, these latters are in differents metallurgical states, cold rolled, annealed and recristallised. One have observed that, texture and metallurgical states are two important factor for appearance of S. B. . To state precisely the influence of the texture, one has done two types of calculation, one based on the stress consideration and the other on the strain consideration. The result shows that the calculation based on stress consideration can better explain the observation of S. B. Than the calculation based on the strain consideration, but this is true only for annealed or recristallised samples. The geometry of the slip system towards the plane that contains transverse direction and normal direction, seem to be an important factor for appearance of the S. B. . If the slip is distributed in a asymmetric manner, there is a tendency to form the dislocation layer which is heterogeneity of deformation, so S. B. Appears. In the other hand we have noticed that the number of slip plane predicted by Schmid law is in relation with the appearance of S. B. , but only in annealed and recristallised samples, when the Schmid law predict only one slip plane, S. B. Are present and in the contrary case these are not present. One think that if the slip occurs on only one slip system, this lends to heterogeneous deformation, but when slip occurs on more than one system, the deformation is homogenous. The reason why these criteria are not apply to cold rolled samples, could be that the criterion don’t take into accompt strain hardening, one think that metallurgical state can influence the appearance of S. B. Because we have annealed one of our materials in a manner that its texture does not change, and experience showed that the appearance of S. B. Is influenced. However we don’t know the reason, because the study by electronic microscope does not show any precipitation.