Evaluation of Dissimilar Metal-joint Strength Utilizing Plastic Flow and Proposal of the Joint Strength Prediction

Abstract

In the automotive industry, various types of materials are used to reduce weight, and it is necessary to join dissimilar metals. The plastic flow joining method is a simple technique for joining dissimilar metals with less thermal strain than welding. In this study, joint tests were conducted under three different conditions (pushing load, tip shape of jig and ring outer diameter) to investigate on joint strength. The strength prediction equation was proposed based on the analysis of the fracture mechanism on joint area during the tensile test. The joint strength increases as the pushing load increases, but excessive pushing load decreases the joint strength when the ring outer diameter is small. The tip shape of the jig had no effect on the joint strength under the conditions of this experiment. The joint strength can be predicted by the shear fracture of the material considering work hardening in plastic flow. The tensile strength of plastic worked material was calculated from Vickers hardness. As a result, the joint strength was determined from the shear strength of material and joint area. The results of calculated strength agreed well with the measured values.