Thermo-mechanical analysis of the MIG/MAG multi-pass welding process on AISI 304L stainless steel plates

Abstract

Welding processes on plates involve complex physical and chemical phenomena which make mathematical modeling difficult. Although coupled thermal-mechanical-metallurgical effects are important, good results can usually be found when numerical models based on heat transfer equation and governing equations of the structural behavior are used. In this paper, a numerical analysis of multi-pass single V-groove weld in butt joint (three passes) of AISI 304L stainless steel, using the conventional MIG/MAG process is presented. The plates are 9.6 mm thick, 200 mm long and 50 mm wide. The numerical simulations were performed by ANSYS® Multiphysics software, considering a moving heat source with Gaussian type distribution, convection and radiation heat transfer on the surfaces and temperature-dependent material properties, for both mechanical and thermal simulations. The von Mises yield criterion and associated flow rule are used together with kinematic hardening and a bilinear representation of the stress–strain curve. The element birth and death technique is employed to consider an appropriate analysis of the welding processes with material deposition. The fusion zone shape, thermal cycles and final distortion of the plates obtained from the experiments developed in the laboratory of research in welding engineering (LAPES–FURG), located in Rio Grande, RS, Brazil, are compared with numerical results. In general, both thermal and mechanical results obtained by numerical simulation are in good agreement with experimental ones. Analysis of the influence of each pass on the plate distortion is discussed.