Study On Mechanical Properties Of Al/Cu Friction Welded Joints

With the application of Al/Cu friction welding components in power batteries of new energy vehicles,its mechanical properties have attracted extensive attention.In this paper,the friction welding joints of aluminum and copper are taken as the research objects,the static test and the fatigue test were carried out,and the mechanical properties of the friction welding joints of Al/Cu were systematically studied in combination with the finite element numerical simulation,so as to provide theoretical support for the practical application of such components.Firstly,the basic mechanical properties of the weld zone of the Al/Cu friction welding joints and base metals were studied.The smooth and notched specimens were designed and processed.The basic mechanical properties of the joints and base metals were obtained by static strength tests.Through metallographic observation test and nano indentation test,the micro zone performance of Al/Cu friction welding joinst was investigated,and the change rule of elastic modulus at the weld was obtained.In this paper,the constitutive model parameters of the nonlinear isotropic hardening model were obtained by combining the static strength test data of pure copper and pure aluminum.Based on the nano indentation test,a finite element model of the Al/Cu friction welding joints was established.Using integration function of the Isight,the constitutive model parameters of the weld zone of the Al/Cu friction welding joints were inversely deduced by the combination of finite element numerical simulation and tests.Finally,the paper studied the fatigue performance of Al/Cu friction welding joints,conducted fatigue tests on notched joints,and obtained the load life curve of Al/Cu notched parts.The scanning electron microscope test was used to analyze the fatigue fracture of the joints.It was found that the fatigue source of the Al/Cu friction welded joints were from the side of the joint weld near the aluminum,extending to the Al/Cu interface along the radial direction,and finally the failure occurred at the Al/Cu interface.Based on the finite element calculation of the Al/Cu friction welding joints,the stress concentration factor at the notch was obtained.On this basis,the fatigue life curve of Al/Cu friction welded joints was established by using the empirical formula of fatigue notch coefficient.