Development of autocompleting friction welding method

Abstract

This paper describes an autocompleting friction welding method that was carried out to weld with an insert piece set between fixed base metals. The base metal was low carbon steel, and the faying surface of the fixed specimen had a 10 mm diameter. The effect of the thickness of the insert piece (insert thickness) on the joining phenomena was investigated. When the insert thickness was 3˙2 mm and the friction welding conditions were a friction speed of 27˙5 s^–1 and friction pressure of 36 MPa, the insert piece had a shear fracture toward the circumferential direction in the peripheral portion of the weld interfaces by the initial peak produced during the friction process. The joint also had cracks at the adjacent region of the weld interfaces, although it had the same tensile strength as the base metal. On the other hand, the joint made using the insert piece with a groove on its peripheral portion had the same tensile strength as the base metal, where it fractured. This joint also had 90° bend ductility without cracks. In this case, the optimum insert thickness was 4˙0 mm, and the thickness at the bottom of the grooves (groove bottom thickness) was 1˙2 mm with an 11 mm inner groove diameter, and the friction welding conditions were a friction speed of 27˙5 s^–1 and friction pressure of 36 MPa. In conclusion, a sound friction welded joint was made by an autocompleting friction welding method.