Optimization of Welding Parameters for Self-Support Friction Stir Welding (SS-FSW) on AA6063 Pipe Joints

A Review of Orbital Friction Stir Welding

“…Both the insert and removal of this internal backing support (mandrel) can be difficult to execute, as the gap between the surfaces should be as close as possible to zero to avoid undesirable deformation of the workpiece, such as turning it into an oval shape. To quantify the deformation promoted by the axial forces without the backing support, Lotpy et al conducted several experiments under various parameters, achieving a minimum deformation of 1260 µm in a butt joint using a square pin profile at 1700 rpm and deformations as low as 542 µm in a stepped joint using the same square pin profile at 910 rpm [60]. So, an expandable mandrel can be a viable solution since it not only promotes an easier insert and removal for constant-diameter tube specimens but may also be the only solution for tubular specimens with a variable diameter.…”