Durability And Strength Analysis Of Self-piercing Riveting Joint Of Aluminum Alloy

In recent years,self-pierce riveting technology as a new type of plate joining technology has gradually gained more and more attention in the field of automobile and aviation.However,due to the influence of the plate itself or the surrounding environment,it will inevitably cause different degrees of corrosion damage to the joint and thus reduce the performance of the joint has adverse consequences.In this paper,the durability and strength of self-piercing riveting joints are studied.The performance changes of self-piercing riveting joints after salt immersion corrosion test are studied in order to provide a theoretical basis for better utilization of self-piercing riveting process.In order to explore the influence of different riveting parameters on the joint performance,2mmAA5052 aluminum alloy and 6mm rivet with hardness H4 were selected as the research object.The pre-compress pressure,pierce pressure,plastic pressure and shape were judged by the evaluation of forming quality and static characteristics.The influence of the parameters on the joints are as follows: The pre-compression pressure is 5MPa,the piercing pressure is 20 MPa,the plastic pressure is 11 MPa,and the stroke is 130.90mm;The double rivet connection is used to investigate the influence of the riveting form on the joint,and the two-way riveting method is found.The one-way riveting method improves joint rigidity and aesthetics,but complicates the stress distribution.In order to analyze the durability of the self-piercing riveting joints,the dry and wet immersion corrosion test chamber was designed to conduct four groups [PFS(2mm+2mmAA5052,19 projection die)?TFS(2mm+2mmAA5052,11 flat die)?TD5(1.5mmDP590+2mm5052,19 projection die)?TD7(1.5mmDP590+2mmAA7075,19 projection die)] of joint salt immersion corrosion test,and the performance after corrosion test was analyzed by weight loss method,statics research and fracture energy spectrum method.The change shows that the corrosion of each joint is corroded after the corrosion test.The corrosion damage of the heterogeneous composite joints are more obvious than that of the same joints.The mechanical properties of each joints after the corrosion test show a certain degree of increase before the decline.Fracture discovery in TD5 group.The TD5 group showed scratches at the 0h fracture.After the corrosion test,the lower sheet was torn and a large number of dimples appeared at the tearing opening.As the corrosion time increased,the impurities in the dimple gradually increased,while the TD7 group during the corrosion cycle,there are scratches on the test piece.When it is corroded to 720 h and 1080 h,the test piece will see the dimple shape after the tear of the lower sheet.The surface of the corrosion sample is caused by the infiltration of Cl element.A large amount of white metal oxide is attached to the contact surface.The fatigue test of PFS group under tension-tension mode was carried out to analysis the influence of dry and wet immersion corrosion test on fatigue properties of joints,double logarithmic lgF-lgN straight line is obtained by fitting each group of fatigue data.It was found that the corrosion test changed the fatigue trend of the joints.Within a certain corrosion time,the fracture mode of the lower plate under the rivet gradually extended to the high-life zone with the increase of corrosion time.The dynamic potential polarization curves of each sample in the TD5 joint were tested and used as boundary conditions to simulate the potential distribution of the self-piercing riveted joint in the salt solution corrosive environment.The contact area between the galvanized steel and the rivet head was found.The galvanized steel of the sample galvanized steel and the aluminum alloy of the sample piece and the contact area between the aluminum alloy and the rivet tube leg of the sample piece have corrosion potential damage,and compared with the corrosion result obtained by the test,the simulation result can be effectively predicted The actual corrosion behavior of the self-piercing riveting joint,but due to the limitations of the simulation test conditions,there is a certain difference in the prediction of the corrosion rate.The simulation process is a simplified self-piercing riveting joint simulation prediction,and it still has reference value to some extent.