Real rotational contact plane in friction welding of different diameter materials and dissimilar materials: Fundamental study of friction welding

Summary

The purpose of this paper is to clarify the mechanism of joint formation as part of a fundamental research programme centred on friction welding. The paper shows that, when combinations of different diameter materials and dissimilar materials are being friction-welded, the phenomenon of rotational plane transfer arises. As a result of this phenomenon, transfer of the rotational plane is found to occur in the central zone of the rotational plane, as demonstrated by observations of plastic flow using a tracer, and the friction welding metal transfers from the filler rod to the plate through the rotational plane. The centre of this rotational plane is defined as the real rotational contact plane in much the same way as in friction surfacing. The area of the real rotational contact plane decreases with an increasing rotational speed and friction pressure, and its diameter is shown to be determined by the friction upset distance (a) and mass of transferred metal (w). The paper further shows that the mechanism of real rotational contact plane decrease can be explained by the critical circumferential speed position of transfer from continuous shear deformation to plastic flow and that a number of phenomena in friction welding associated with an increase in the rotational speed and friction pressure can be explained by the decrease in the area of the real rotational contact plane