Effet de vieillissement naturel sur les propriétés mécaniques de deux toles AlMgSi

Abstract

In this work , we have undertaken the study of two sheets AlMgSi. These arouse great interest for their privileged use in the automotive and the aerospace industrie . The aim of the present work is the study of transformations reactions of phases and the influence of natural ageing on the mechanical properties of AlMgSi alloys . For the characterization of these materials, we have used various experimental techniques such as differential calorimetric analysis (DSC), optical microscope, microhardness measurements, X-rays diffraction and dilatometry. DSC stud ies enabled us to follow the transformation of the various phases of the sequence of precipitation in these alloy s. The microstructure of alloys was characterized by optical microscopy. The characterization by diffraction of x-rays did not highlight the presence of another phase in add ition to the matrix α-aluminium; the non detection of other phase could be due to its small volume fraction. But, the use of x ray diffraction revealed the presence of anisotropy, as the sheets have been rolled. The microhardnes s measurements showed that the excess of Mg does not improve the mechanical properties of AlMg Si alloys. The dilatometric results confirmed the presence of an anisotrop y. The thermal expansion coefficient measurements differ from one direction to another and from one alloy to anot her .