Is any pre-heating required or recommended before commencing the welding process?

No, external preheating is not necessary for a welding operation with FSW technology.
We have integrated a delay phase into our welding process that avoids this phase. The preheating action is thus carried out by the tool itself while continuing to rotate in the same place. It is also possible to increase the heating of the material by reducing the lowering speed or increasing the rotation speed.