Abstract: A method of operating on a workpiece comprises offering a probe of material harder than the workpiece material to a continuous surface of the workpiece causing relative cyclic movement between the probe and the workpiece while urging the probe and workpiece together whereby frictional heat is generated as the probe enters the workpiece so as to create a plasticized region in the workpiece material around the probe, stopping the relative cyclic movement, and allowing the plasticized material to solidify around the probe. This technique, which we refer to as "friction plunge welding" provides a very simple method of joining a probe to a workpiece. The method can be used for repairing cracks and the like within a workpiece or for joining members, such as studs or bushes, to a workpiece.

Abstract: Shielded arc welding apparatus advances a consumable electrode towards a workpiece; applies a welding voltage between the electrode and the workpiece; and applies an auxiliary voltage between the electrode and the workpiece, whereby the auxiliary voltage initiates an arc between the electrode and the workpiece before the electrode engages the workpiece.