Abstract: Butt welding of workpieces of similar or dissimilar materials, such as aluminum to aluminum and/or aluminum to steel, having similar or dissimilar cross sections is accomplished by a frictional welding process wherein the average relative speed of the faying surfaces is between about 4 and about 25 feet per second, the pressure urging the faying surfaces into mutual engagement is between about 7500 and about 15,000 pounds per square inch while energy is supplied to the weld area in the range between about 4000 and about 17,000 foot pounds per square inch of weld area, and the formation of the weld is achieved within about 650 milliseconds.