| T-type fillet weld is widely used in the processing of bridge,ship,aviation,engineering machinery and other parts.In practical engineering,in order to ensure the full penetration of the weld and improve the welding quality and production efficiency of the workpiece,the form of single-sided V-groove with blunt edge is often used in the T-fillet welding of medium and thick plates.Because of the significant difference of heat dissipation between the V-groove with blunt edge and the ordinary symmetrical weld,it is easy to produce the welding defects of incomplete fusion or over penetration when backing welding.In order to realize the effective control of the full penetration of the asymmetric fillet weld,it is necessary to explore the heat input of the asymmetric fillet weld and reveal its penetration forming mechanism.Because of the complexity of the welding process,it is difficult to understand the welding process only through the calculation of test or analytical model.With the development of computer science and finite element technology,the numerical simulation technology of welding process is becoming a convenient tool for people to study the mechanism of welding penetration.At present,the research on numerical simulation of fillet weld focuses on adding appropriate heat source model to study the penetration.This model ignores the complex interaction between arc and molten pool,and assumes the ideal heat source model.Although it helps us to understand the penetration mechanism of fillet weld to a certain extent,it inevitably has some deviation from the actual situation.Based on the actual situation of welding and the source of welding heat source,this paper unifies the welding arc and weld pool.Aiming at the asymmetric angular root welding,a three-dimensional unified model of arc molten pool coupling is proposed for the first time.The model is based on magnetohydrodynamics theory,coupled with the electric field,magnetic field,flow field,temperature field and force field.The welding arc shape and temperature field,workpiece temperature field and penetration condition and the angular deformation of welding parts are simulated,and the arc shape and temperature are simulated respectively.The temperature field(fusion line)of the workpiece and the angular deformation of the weldment are tested,and the correctness and applicability of the arc pool coupling model are proved.Finally,based on this model,the numerical simulation of the arc temperature field,the penetration of workpiece and the angular deformation of weldment under different welding parameters is carried out,which is verified by experiments,and the influence of different parameters on the welding quality of asymmetric fillet root welding is quantitatively analyzed.The results show that the welding current has the greatest influence on the penetration forming and the angular deformation of the weldment;the welding angle affects the deflection of the weld pool center and the angular deformation of the weldment by affecting the heat distribution of the arc,and the heat input distribution of the workpiece surface can be controlled by controlling the welding angle,so as to control the welding quality.This study has a certain guiding effect on the quality control of asymmetric fillet root welding. |
