Numéro
J. Phys. IV France
Volume 01, Numéro C3, Octobre 1991
DYMAT 1991 - 3rd International Conference on Mechanical and Physical Behaviour of Materials under Dynamic Loading
Page(s) C3-347 - C3-352
DOI http://dx.doi.org/10.1051/jp4:1991350
DYMAT 1991 - 3rd International Conference on Mechanical and Physical Behaviour of Materials under Dynamic Loading

J. Phys. IV France 01 (1991) C3-347-C3-352

DOI: 10.1051/jp4:1991350

THE MICROSTRUCTURAL EVOLUTION DURING DEFORMATION UNDER SEVERAL STRAIN RATES IN A COMMERCIAL 5182 ALUMINIUM ALLOY

K. HIGASHI1, T. MUKAI1, K. KAIZU1, S. TSUCHIDA2 and S. TANIMURA1

1  Department of Mechanical Engineering, College of engineering, University of Osaka Prefecture, Mozu-umemachi, Sakai, Osaka 591, Japan
2  Technical Research Laboratories, Sumitomo Light Metal Industries, Ltd, Nagoya, Aichi, Japan


Résumé
La contrainte d'écoulement d'un alliage d'aluminium 5182 a été déterminée en fonction de la vitesse de déformation entre 10-3 s-1 et 4.103 s-1 à température ambiante. L'alliage d'aluminium montre une sensibilité négative à la vitesse de déformation dans un domaine où celle-ci est inférieure à 102 s-1, la contrainte d'écoulement maximum décroît quand la vitesse de déformation augmente. Cette tendance est aussi observée pour d'autres alliages d'aluminium au magnésium tels le 3004 et le 7N01. On déduit de l'observation par M.E.T., que la diminution de la densité de dislocations résultant de l'arrangement en réseau des bandes de déformation de dislocation conduit à la contrainte minimum pour la déformation où la sensibilité négative à la vitesse de déformation est observée.


Abstract
The flow stress of a commercial 5182 aluminum alloy has been investigated as a function of strain rates in the range from 1x10-3 to 4x103s-1 at room temperature. The 5182 alloy exhibited the negative strain rate sensitivity of flow stress in a strain rate range below 102 s-1, of which the maximum flow stress decreased with increasing strain rate. This tend in flow stress with strain rates was observed for other commercial aluminium alloys which include magnesium atoms in solute such as the 3004 and 7N01 alloys. It seems that the microstructual evolution during deformation has occurred in these alloys. The incremental strain rate tests revealed that the true strain rate sensitivity is positive under the same structure of alloys, and there appear to be the negative strain rate sensitivity corresponding to the microstructural evolution after some deformations. From the observation by transmission electron microscopy, the decreasing of dislocation densities resulting from the arrangement of the network-like deformation bands by dislocations with straining, lead to the lower stresses at the strains where the negative strain rate sensitivity is observed.



© EDP Sciences 1991