Flash (butt) welding can be applied to a wide range of materials including carbon and stainless steels, nickel alloys, aluminium alloys and copper alloys. Materials containing alloy additions which form strong stable oxides are more susceptible to weld interface flaws and welding conditions should be adjusted accordingly.
Flash welds in carbon steels have high strength but low impact toughness. Post-weld heat treatment, either locally in-machine or by alternative means, is necessary where specific impact toughness performance is required.
Much higher upset forces are required for materials with high hot strength, for example stainless steels and nickel alloys. Aluminium alloys require high welding currents and very high upset speeds because of the high electrical and thermal conductivity of these materials. The process can also be used to weld titanium, but an inert gas shield may be necessary to prevent embrittlement by nitrogen or oxygen absorption.
The process finds application in most major industry sectors. For example in the road transport industry wheel rims are made from flash welded rings. In aerospace it is used to weld undercarriage struts and engine rings. Drill pipe for the oil sector may have flash welded fittings attached, and in rail transport the process can be used to join rails and crossovers.