In welding of a thin plate, welding deformation is a severe problem. It is difficult to correct the welding deformation after welding. Therefore, the welding deformation should be avoided before or during welding. As the welding deformation is generated by thermal cycle during welding, it is thought low heat input joining process is efficient to decrease the welding deformation. In this study, friction welding was proposed as lower heat input welding process than arc welding. MAG welding was also carried out to compare welding deformation and heat input. However, it is difficult to compare heat input between friction welding and arc welding. Because, there in no general heat input calculation in friction welding and does not define the weld line in friction welding. To compare the heat input directly, pipe circumference was assumed to weld line and calculated heat input by simplified heat input rate, which was proposed by authors.
The appearance of friction welded joint was sound and tensile tests revealed the fracture occurred at the base metal of plate. In friction welding, the deformation of plate was smaller than that in MAG welded joints. Heat input in friction welding was 10-30% in MAG welding by direct comparison for same dimension of joints. The time for welding was also smaller in friction welding. Friction welding is small deformation and efficiency process for joining of pipe and thin plate.
