Abstract
Residual stresses have been numerically determined in welded joints. In this study, the numerical model is based on the coupling of different physical phenomena considering the thermal, mechanical and metallurgical nature of a welding process. The ABAQUS software program was used to perform the numerical simulations, based on the finite element method (FEM). 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, in which a 60 mm × 50 mm and 3 mm rectangular ASTM AH36 steel plate was used for the TIG process simulations. Throughout this work, the optimization of the welding procedures currently practiced in petrochemical and ship building industries can be applied to reduce the levels of residual stresses.
Highlights
The multiplicity of phenomena affecting a welding process and their microstructural heterogeneity has been a complicating factor for the theoretical analysis and prediction of the physical and mechanical properties of welded joints
The aspects related to the mathematical modeling of complex welding procedures were pondered with the finite element method (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; 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, in which a 60 mm × 50 mm and 3 mm rectangular ASTM AH36 steel plate was used for the TIG process simulations
Summary
The multiplicity of phenomena affecting a welding process and their microstructural heterogeneity has been a complicating factor for the theoretical analysis and prediction of the physical and mechanical properties of welded joints. The state of residual stresses is an important factor that determines the load capacity and the lifetime of a structural element. Residual stresses greatly influence the characteristics of the mechanical strength of the structural elements, considering their development after several technological processes as well as welding, thermomechanical processes, surface or thermochemical treatments, all caused by heterogeneous plastic deformation, sometimes supported by thermal action and/or phase transformations. Tsirkas et al [2] conducted simulations research to determine the temperature field in welded joints using laser welding in order to obtain further the stress field. Monin et al [3] experimentally obtained residual stresses using X-ray diffraction
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