Resistance butt welding is used to join components of similar cross section by making a weld across the entire section in a single operation. Heat is produced in the weld region by resistance to the passage of the welding current through the parts, which are held under a preset end force. As the material heats, the force forges the soft material to consolidate and complete the joint.
Resistance butt welding is thus a solid state process. The force across the interface causes deformation which brings the surfaces into sufficiently close contact to make a weld, and there is some expulsion of material which carries oxide film and contaminants out of the joint.
Applications include wire and rod joints up to about 16mm diameter, including chain, and narrow strip joints such as automobile road wheel rims.