Analysis of TB2 rivet forming quality and mechanical properties of thin sheet riveted joints based on different riveting methods

The riveting of high-strength rivets (such as TB2 (Ti-5Mo-5V-8Cr-3Al)) faces difficulties in forming. This article compares the electromagnetic riveting (EMR) and the hot riveting (HR) joints of two typical TB2 rivets (the flat cone head rivet and the countersunk head rivet). The interference and hardness distributions of the rivets were measured, and the strength of the joints was tested. Moreover, the microstructures of rivets after riveting and the fractured surfaces after the shear and pull-out tests were both observed. The results indicate that the interference of the EMR joints is greater and more uniform than that of the HR joints. The deformation of the EMR driven head is more severe than that of the HR. Higher hardness is measured in the driven head and the rivet shank at the positions of severe deformation. The hardness of the EMR driven head and rivet shank is higher than that of the HR. Additionally, it will not cause a decrease and even slightly improve in the mechanical properties of the joint when using the EMR riveting TB2. The pull-out strength of flat cone head rivet joints is significantly higher than that of countersunk rivet joints due to the influence of the structure strength of the manufactured head. The fracture mode of all joints is mixed fracture. However, the failure mode of joint varies greatly due to the influence of rivet structure and riveting method. When using the EMR instead of the HR to rivet the TB2 rivets, it will not cause a decrease in the mechanical properties of the joint. Therefore, it is indicated that the EMR can be used to replace the HR.