Influence of FSSW parameters on fracture mechanisms of 5182 aluminium welds

Effect of tool design and process parameters on properties of Al alloy 6016 friction stir spot welds

“…Higher tool rotation speed is believed to generate more frictional heat, which is beneficial for formation of a larger bonded region. Bozzi et al (2010) proposed that the size and location of the stir zone and the unwelded interface tip slop played a determinant role on the weld strength. The upward and inward climbing hooking observed for the CP tool at higher tool rotation rates significantly decreased the bonded region and induced the easy crack propagation during lap-shear loading, resulting in the reduced separation load.…”

Effect of grain size and residual stress on the corrosion resistance of friction stir spot welded AZ31B joints

“…The dissolution of second‐phase particles eliminated harmful microgalvanic cells formed between the active α‐Mg matrix and the noble β‐phase particles, and increased the concentration of aluminum in the matrix. Although both mechanisms are believed to be responsible for the increased corrosion resistance properties of the stir zone, the effects resulting from changes in grain size in regions adjacent to the stir zone were not taken into account . In a similar manner, the effects of changes in residual stress and strain were also not considered.…”

“…The FSSW process introduces residual stresses and internal strain in welded joints via a number of different mechanisms . First, when the tool penetrates into the sheet metal, it induces severe plastic deformation and this results in compressive stresses in the plane normal to the tool centerline and tensile stresses in the direction parallel to the axis of the rotating tool.…”

“…First, when the tool penetrates into the sheet metal, it induces severe plastic deformation and this results in compressive stresses in the plane normal to the tool centerline and tensile stresses in the direction parallel to the axis of the rotating tool. Material surrounding the welding spot is deformed elastically, and the incompatibility between the deformed material in the weld zone and surrounding bulk material creates elastic residual stresses that are tensile in the radial direction and compressive normal to the axis of the rotating tool . Residual stresses are also produced as a result of contraction when the joint cools to room temperature.…”

FEM model for the thermo-mechanical characterization of friction stir spot welded joints

“…Besides, in [15] it was stated that the lap shear strength of the joints can be improved by increasing the dwell time or in general by optimizing this parameter [17]. On the contrary, in other researches [18] it was observed that the resistance of the joints decreases for decreasing values of the tool rotating speed.…”