Structure and Mechanical Properties of Friction Stir Weld Joints

Residual stresses of a magnesium alloy (AZ31) welded by the friction stir welding processes

“…These defects disappeared with increasing W, but with a further increase, internal voids, lack of bonding and surface cracking occurred due to excess expelled material. These results are consistent with the literature [5,6,7,8]. The tool used had a 5 mm pin diameter and 10 mm shoulder.…”

“…The tilt is different along the side. In the literature, these local orientation evolutions are explained as being mainly due to shear plastic flow along the pin column surface [6,7]. These zones were deformed and influenced by heat and high plastic deformation.…”

“…From a mechanical point of view, considering the initial nature of the base metal (AZ31, AZ91, WE45, and AZ61), results has shown anisotropy in mechanical properties. These variation of mechanical properties have been linked principally to the initial fabrication process of the base metal and then to the welding process [6]. Welding processes equally produce residual stresses which are linked to the large deformation in FSW.…”

“…These studies have enabled a better understanding of the relationship between the welding processes, the weld quality, the microstructure and the residual stresses of the weld [3,4]. Several studies have shown that the plasticity is a fundamental factor that governs the mechanical properties of the welded joints [5,6]. Most studies have shown the complexity of FSW and associated heterogeneities.…”

“…Welding processes equally produce residual stresses which are linked to the large deformation in FSW. For FSW peaks in residual tensile stress are observed in the TMAZ in the longitudinal direction and compressive residual stress peaks occur in a transversal direction in the fusion zone or nugget [6]. In the case of this study, a rolled magnesium alloy AZ31 was used for the welding tests to understand the evolution of microstructure and mechanical properties in particular the calculus of residual stresses.…”