Abstract
This report describes the joint strength of fine grained steel (FGS) friction welded joints by using the low heat input friction welding method (LHI method) which was developed by authors. The FGS base metals were joined by using the continuous drive friction welding machine with an electromagnetic clutch in order to prevent braking deformation during rotation stop. It was clarified that the friction welded joints with 100% joint efficiency could be obtained by using only the friction stage up to initial torque without the forge (upsetting) stage. That is, the joint tensile strength of the friction welded joints was obtained at the time that the friction torque reached the initial torque. In addition, the joint welded by the LHI method did not cause softening and the grain growth in the heat affected zone. As a conclusion, the LHI method without the forge stage to the FGS base metal welds provides the advantages of less burn-off, less burr, non-softening and less grain growth.
