OBTAINING TEMPERATURE FIELDS AS A FUNCTION OF EFFICIENCY IN TIG WELDING BY NUMERICAL MODELING

Abstract

The temperature field serves as the basis for predicting levels of residual stress in a welded joint. The aspects related to the mathematical modeling of complex welding procedures were pondered with the FEM: variations in the physical and mechanical properties of the materials as a function of the temperature, the transience and the speed of the welding process, the material phase transformations, the different mechanisms of heat exchange with the environment (convection and radiation), all them associated with a high level of nonlinearity. The heat source used in this analytical model for heat supply was the double ellipsoid model proposed by Goldak (2005), in which a 60 mm x 50 mm and 3 mm rectangular ASTM AH36 steel plate was used for the TIG process simulations. It was made a comparison of temperature fields for three different values of process efficiency (60%, 70% and 80%). The results showed many differences in the temperature fields following changes in the levels of residual stresses which will be determined in further studies.