Research On Current Auxiliary Diffusion Bonding/gas Bulging Forming Properties Of GH5188 Alloy

Compared with nickel base superalloy,cobalt base superalloy GH5188 has higher initial melting temperature,better corrosion and oxidation resistance,better durability,excellent cold and hot fatigue resistance and welding performance,and has a broad application and development prospect in the field of aerospace.Current auxiliary thermoforming is a rapid and efficient thermoforming technology,which uses the Joule heat generated when a large current flows through a metal conductor to raise the temperature of the metal blank to the required temperature in a short time.In this paper,current auxiliary thermoforming technology was applied to the diffusion bonding and gas expansion forming process of GH5188 superalloy sheet,and the technological characteristics of GH5188 superalloy sheet in the process of current auxiliary diffusion bonding and gas expansion forming were discussed in depth.Firstly,the current heating behavior of GH5188 superalloy was studied.The experimental scheme of GH5188 current heating was designed,the theoretical analysis of GH5188 heating process was carried out and the finite element model was established.Finally,the current heating experiment of GH5188 was carried out,and the current heating characteristics of GH5188 superalloy were explored through the combination of finite element simulation and experiment.The temperature distribution and current density distribution of GH5188 double-layer plate after current heating are analyzed by finite element simulation.According to the temperature distribution curve of the central line of the double-layer plate,it is known that there is a uniform temperature zone in the middle of the plate after GH5188 current heating.GH5188 current heating experiment was carried out.It is found that the temperature of the negative electrode is higher than that of the positive electrode when the temperature of GH5188 reaches equilibrium.The heating curves of different current density are obtained by changing the power supply current,and their characteristics are analyzed.In order to explore the feasibility of application of current auxiliary forming technology in diffusion bonding of GH5188 superalloy sheet,a new current auxiliary diffusion bonding equipment was designed.The finite element analysis of GH5188 current auxiliary diffusion bonding process is carried out.By changing the current loading mode,the slow temperature rise in the current auxiliary diffusion bonding process was improved.The influence of cavities on the current and temperature field was discussed.The equilibrium temperature of current auxiliary diffusion bonding of GH5188 alloy sheet under different current density was measured by experiment,and the experiment of current auxiliary diffusion bonding of GH5188 alloy sheet was carried out.Based on the analysis of the distribution of the elements in the weld,it was concluded that the most of the precipitated material in the weld was M6 C.Finally,the shear strength of the specimen was tested,and the shear strength of the current auxiliary diffusion bonding experiment was 615 Mpa.At last,the properties of GH5188 superalloy sheet were studied,a set of current auxiliary free bulging die was designed,and the finite element analysis of GH5188 current auxiliary free bulging was carried out.The simulation results showded that with the increase of the ratio of height to diameter,the temperature at the top of the bulging part decreases gradually.It is also found that there is a flow around the current streamline in the current auxiliary free bulging process.A set of current auxiliary diffusion bonding / gas expanding forming device is designed,which can provide a processing idea for the preparation of GH5188 double-layer structure parts.