Numerical Simulation And Synthetical Analysis Of Welding Hot Processes

ANSYS software is similar joint to used simulate the temperature fields and the residual stress fields about Q235 butt-welding of TIG and 20g' butt-welding of GMAW and T91 martensitic steel. The Gauss and double-ellipsoid are chosen as heat source models, and used command to apply load of moving heat source. The uneven grid of meshes are used, also the impact of phase change latent is considered adequately. Besides, the varying thermal and mechanical properties with temperature varying are taken into account in detail. Simulation in both-pass welding employs dead-live unit method to activate weld by one for one in computation. The sequential coupled method is introduced to calculate the effect of thermo-mechanical coupling.The content of study in this paper: the distribution rule is discussed here Two heat source models including Gaussian source model, double-ellipsoid source model were loaded in Q235 about the butt-welding of TIG by comparison about the simulation results and computation about the section dimensions of the seam welding. The applicability of source models was analyzed. Dynamic temperature fields were simulated by double-ellipsoid heat source model in the 20g' butt-welding of GMAW and in T91 similar join. Microstructure and hardness of the HAZ were predicted by the welding cycle and CCT diagram. Numerical Simulation of Welding Temperature Fields and Stress Fields in T91 Steel were analyzed by three welding process parameters including no preheating before welding and before welding and heat treat after welding in preheating 250℃Preheating before welding and heat treat after welding's necessity were discussed.Simulation results indicate: The results including the maximum temperature of melting pool and the section dimensions of the seam welding and the resident time at high temperature show double-ellipsoid distribution accord with the experimental values better than Gaussian distribution.Preheating has little significance in reducing residual stress of small-calibre thin wall pipe. welding residual stress were recede observably by after-weld heat treatment process.Finally, It is validated that the finite element model and simulation results are exact, and simulation methods are reasonable by microstructure, hardness and the section dimensions of the seam welding. Founded heat source model was fit for not only TIG but also GMAW. The heat source model was fit for not only slab of butt-welding but also tubular butt-welding.