Influence de la vitesse de soudage par friction malaxage sur les propriétés mécaniques locales et la microstructure d’un alliage d’aluminium Al-6%Mg

Abstract

One aspect of FSW process that has rarely been discussed is the influence of the welding parameters on the local mechanical properties of the different zones affected by the welding. Specifically, the evaluation of local mechanical properties using a mechanical testing method known as Shear Punch Testing (SPT). There are also very few studies focusing specifically on FSW welding of work hardened aluminum alloys containing more than 5% Mg. In order to fill these gaps, the objective of this project is to quantify the effect of friction stir welding parameters on the local mechanical properties and the microstructure of an Al-6% Mg-H18 alloy. To do this, two welds were produced at different feed rates (50 mm / min and 120 mm / min) and their respective microstructures were analyzed in detail by optical and electron microscopy including EBSD. Microhardness and Shear Punch Testing were also carried out to assess the local mechanical properties of each weld. Significant differences in microstructure and mechanical properties were observed between the two welds. Microhardness was first linked to the microstructures observed in each of the areas affected by welding. The comparison of SPT results with microhardness also validated the use of the Shear Punch Test as a mechanical test method complementary to microhardness testing. The SPT made it possible to accurately measure the mechanical resistance of the zones affected by welding but proved to be less suitable for the assessment of flow stresses. However, a lot of information on the mechanical behavior of the zones affected by welding could be extracted from the SPT stress-displacement curves. As this information cannot be acquired by microhardness testing, the results of the SPT tests allowed studying of new aspects not reported to date in the scientific literature related to FSW.

Date	29 Sept 2020
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Mohammad Jahazi (Supervisor) & Pierre Bélanger (Co-supervisor)