Numerical Simulation And Experimental Study Of Pulse Current Assisted Welding Under Low Electric Heat.

Research on the influence of electric pulse on metal solidification and solid state phase transition has been widely carried out home and abroad.Through literature review,the author found that using electric pulse during the complex welding process is not that much.The study related to the microstructure and properties of the electric pulse to change the welding area and the heat affected zone is not easy to be found.The properties of welded joint are closely related to the area of coarse grain area.Large heat input of SAW can enlarge the area of coarse grain zone and make the performance of the joint get worse.The life of the welding parts depends on the welding quality.For high grade pipeline steel X80 level or above,the quality requirements are higher.In order to improve the performance of welding coarse grain zone, the method of increasing the content of micro alloy(the steel grade) is widely used to solve the problem. In this paper, the performance of the welded joint is improved by using the electric pulse auxiliary welding method. The influence of electric pulse on the welding process is studied by numerical simulation and theoretical and experimental research methods.The main research contents of this paper are as follows:Firstly,ANSYS finite element simulation. Using ANSYS analysis of heat, the welding process of the applied process of pulse current electric and magnetic coupling. Under the condition of low electric heating, the parameters such as pulse width, pulse frequency and input current are analyzed. The electromagnetic parameters of the welding joint and the electromagnetic parameters of the heat affected zone are analyzed,too.Secondly,based on the theory of magnetic iron of simplified pulsed current electromagnetic field are analyzed, and combined with the theory of the solid state phase transition of weld solidification and cooling process in the pulse effect of electromagnetic field on the weld and heat affected zone are analyzed in theory. The analysis found that pulsed electromagnetic fields affect the alpha and gamma phase shift pulse electromagnetic field have different effects will prompt gamma phase so as to refine the grain.Thirdly,welding experiment research. Develop experimental parameters table and according to experimental parameters table on each pulse parameters on the specimen in the welding is applied in the process of pulse current and from the weld and heat affected zone according to the position of the grain size of discuss pulse parameters influence on each part of the degree.Finally,the experimental process parameters are simulated and the experimental parameters are confirmed by the numerical simulation results.The accuracy of the simulation results is verified by experiments.