Research On Characteristics Of Reducing Welding Residual Tensile Stress By Cavitation Jet

The self-excitation pulsed cavitation jet with low pressure and large flow is a new and efficient jet technology,which has its own unique advantages.It has been widely used in chemical cleaning,industrial cutting and oil drilling.However,compared with the increasingly mature scientific research and engineering application of the technology of water jet shot peening at high pressure,the technology of cavitation jet shot peening has not been widely applied.In this paper,the operation characteristics,the current research status and the application prospect of the cavitation jet shot peening technology are reviewed,and the existing problems in the research process are summarized.On the basis of the large general finite element analysis software Abaqus,the author uses the cavitation jet shot peening technology to make a theoretical study and numerical simulation on the special welding residual stress field of the butt welding on the flat steel plate.In this paper,the stress and strain field of welding is simulated on the basis of thermal elastoplastic theory,and the contact element technique is used to establish the finite element model of the jet impact problem,and the mechanical behavior of the impact contact and the effect of shot peening are calculated and analyzed.The three-dimensional finite element model of the butt welding process of flat steel plate is established,and the thermal coupling effect is calculated by indirect coupling method.The standard Goldak double ellipsoid heat source model is used to simulate the welding arc,and the moving load of welding heat source is realized by heating flux density on the surface of solid unit.The thermophysical properties of materials with temperature change are considered in the model,and the parameters are appropriately selected and adjusted.The non-uniform mesh method is used to create the model meshes.The mesh in the weld and the surrounding area is dense,and far away from the weld area is sparse.For the highly nonlinear analysis of welding thermal structure,a series of measures have been adopted to ensure the convergence and accuracy of the solution.Finally,the calculation results are analyzed and the correctness of the simulation is proved.For the first time in the numerical simulation study of cavitation jet shot peening to eliminate welding stress,the contact element technique is used to establish the peening finite element model to simulate and calculate the impact effect.The contacted part of the peening surface and the plate surface is dispersed on the surface of the base body by contact element.In the process of calculation,reasonable time steps and constant values of contact elements are needed to ensure the convergence and accuracy of calculation.The results show that the welding residual stress in the weld joint and the heat affected zone is significantly reduced after the cavitation jet shot peening treatment,and the compressive stress has been produced in the weld zone.It is proved that cavitation jet shot peening has the effect of reducing welding residual stress.