Numerical Simulation Of The 3-D Transient Temperature And Stress Fields For GTAW Based On SYSWELD Software

It is a key issue to establish an appropriate model of the heat source in the simulation of Gas Tungsten Arc welding. A 3-dimensional transient numerical model for Gas Tungsten Arc welding stainless sheet steel was created to simulate temperature fields by Finite Element Method based on SYSWELD software and its 2nd development. A double ellipsoid heat source mode is adopted to depict the distribution of a moving GTA welding arc. The model adopts the distribution of heat flux of moving heat source and concerns with the effects of vaporization at the free surface of molten pool, the convection heat loss at the surface of work piece and the effect of phase-change latent.Numerical simulation of molten pool behavior in GTA welding is carried out by applying software SYSWELD and improving it to understand fluid flow and heat transfer in arc weld pools more deeply and provide the theorizing basis of acquiring finer welds for stainless steel. It can set many different kinds of boundary conditions according to the characteristics of SYSWELD. The model applies both uniform and Non-uniform mesh considering computing precision and efficiency.The results of numerical simulation demonstrate the process of transient weld pool development for TIG welding of stainless steel work piece. The dynamic process of the weld pool forming, growing up, penetrating and reaching quasi-state steady and the movement of the temperature distribution in work piece are quantitatively analyzed. Transient variations of temperature fields and weld pool geometry have been predicted and verified. The relationship between the welding process parameters (welding current and welding speed) and weld pool shape, the fluid flow of weld pool as well as temperature field are described on the basis of computed results.GTAW experiments on stainless steel are carried out, and based on the weld pool images captured in GTAW welding process, geometric parameters of weld pool are determined to verify the developed model. It is found that the calculated width and length of molten pool are in agreement with the experimental ones. Numerical simulation results are in good agreement with experimental ones. Based on the calculated temperature profiles, the predicted thermal stress and strain and the variations of thermal distortion of the welded work piece match well with the practical situations. It provides with basic data for the optimization of GTAW and further verifies the advantages of GTAW process.