| As a new type of solid phase welding technology,friction plug welding has the advantages of energy saving,green environmental protection and good joint performance,and has wide application prospects in the fields of shipbuilding,aerospace and other fields.In this paper,an analytical model of the temperature field in the initial stage of friction plug welding is established by experimental and theoretical research methods,correlating the fundmental response variables process parameters and material property parameters to temperature,which can provide a theoretical guidance for the selection of process parameters in actual production process.The main contents and achievements are as follows:Firstly,with the experimental study of 7075-T6 aluminum alloy friction plug welding as the main means,the heat generation and temperature field evolution of the initial stage of friction plug welding,as well as the microstructure and microhardness of welded joints were studied in depth.The basic law of the linear growth of the initial stage heat production power is found,the importance of the initial stage to the welding process is proved,and the microstructure and microhardness of welded joints under thermal coupling are analyzed briefly.Secondly,based on tribology,elastoplastic mechanics and heat transfer theory,the theoretical analysis of the initial stage of friction plug welding is carried out.According to the continuity of heat production,the analytical formula of peak power is obtained.The linearization hypothesis of heat production power is proposed with the experimental achievements,and then the linear heat production model of the initial stage is established.In summary,a mathematical model that can fully describe the unsteady heat conduction problem in the initial stage of friction plug welding is given.Finally,the above mathematical model is solved by Laplace transform method,and an analytical model of the temperature field in the initial stage of friction plug welding is obtained,which correlates the temperature with the process parameters and material physical parameters.Based on the linear heat generation model,a three-dimensional finite element model of 7075-T6 aluminum alloy friction plug welding was established by using finite element software.Combined with the 7075-T6 aluminum alloy friction plug welding experiments and its numerical simulation,the correctness and reliability of the analytical model are verified from the three aspects of peak temperature,duration and temperature variation curve in the initial stage. |
