Numerical Simulation And Experimental Verification For Welding Deformation Control Of Railway Freight Car Side Wall

Welding technology plays a vital role in railway vehicles manufacturing process.A local highly concentrated instantaneous heat source of the welding process usually result in an uneven and unstable temperature field.Also,for fusion welding,the base metal and filler metal at the weld will be melted due to local high temperature,accompanied by a series of metallurgical reactions and microstructure transformation.Therefore,welding-induced deformation will inevitably occur after the process is completed.The deformation has a significant influence on the manufacturing accuracy and manufacturing quality of railway freight cars.It is essential to study the prediction and control of welding deformation.This paper takes the railway vehicle side-wall(Q345NQR2 steel)as the research object based on the finite element numerical simulation method.It sets up several test programs with different welding methods,welding distances,and sequences to study welding deformation control.Firstly,the finite element models of the partial and overall typical structure(single grid plate)of electric riveting,plug welding,and section welding of railway freight car side-walls(Q345NQR2 steel)were established respectively.Based on checking the combined heat source model,sequential heating was adopted.Coupling method,using three-dimensional thermoelastic-plastic finite element method to simulate the local side-wall structure,analyze the results and extract the shrinkage strain;Then use the inherent strain method to perform an elastoplastic calculation on the typical structure of the side wall(single grid plate),and obtain the welding deformation results of the typical form of the side wall(single grid plate);After that,the corresponding welding test is carried out,and the numerical simulation results are compared with the actual test results to verify the accuracy of the numerical simulation results.And,the welding deformation of the typical overall structure(single grid plate)of the side wall with different welding spot spacing and welding sequence was calculated.By comparing and analyzing the calculation results,the following conclusions are obtained.(i)Under the three welding processes of electric riveting,plug welding and segment welding,the maximum welding deformation position of the typical structure of the side wall(single grid)is located in the middle of the bottom plate;(ii)Under the same solder joint layout and welding sequence,electric riveting welding is easier to control welding deformation than segment welding and plug welding.The maximum welding deformation of the riveting welding process is more minor than the minimum deformation of plug welding and segment welding;(iii)Regardless which process of the three,when the same welding method is adopted,the layout of the solder joints with large spacing will obtain better welding deformation control results;(iv)For the three welding processes of electric riveting,plug welding and segment welding,when the same solder joint layout is adopted,the different welding sequence has little effect on the result of post-welding deformation.The thesis research provides a reference for the control of post-welding deformation of side-wall of railway freight car and similar thin plate structures,the selection of welding technology and the setting of welding spacing,and has good engineering significance.