Banded structures better known as "onion rings" are one of phenomena that appear in the microstructure during friction stir welding. These bands consist of a succession of layers of material in the weld nugget visible under an optical microscope. The welding parameters leading to their appearance as well, as their effect on the quality of the joint, are still subject to many research with different conclusions. In this context, the aim of this research is, initially, the microstructural characterization of alternate bands in order to understand the mechanism of their formation. Friction-stir welding experiments were carried out with different rotational and advancing speeds and two different tools on two aluminum alloys: 6061-T651 and 6082-T6. A more detailed characterization performed on a weld made with a rotational speed of 1750 rpm, an advancing speed of 200 mm/min and a trigonal tool, revealed that the difference in contrast between the bands was due to an alternation between bands containing high angle grain boundaries and others containing low angle grain boundaries. A study of the mechanical properties of the different areas of the weld was also carried out in order to understand the influence of these bands on the quality of the weld.
| Date | 17 Oct 2017 |
|---|
| Original language | French |
|---|
| Awarding Institution | - École de technologie supérieure
|
|---|
| Supervisor | Mohammad Jahazi (Supervisor) & Victor Songmene (Co-supervisor) |
|---|
Zoghlami, M. (Author),
Jahazi (Supervisor) &
Songmene (Co-supervisor),
17 Oct 2017Student thesis: Master's thesis › Master in Engineering: Mechanical Engineering