Comparative analysis of TIG welding distortions between austenitic and duplex stainless steels by FEM

In this study, thermal stress analyses were performed in the tungsten inert gas (TIG) welding process of two different stainless steel specimens in order to compare their distortion mode and magnitude. The growing presence of non-conventional stainless steel species like duplex family generates uncertainty about how their material properties could be affected under the welding process. To develop suitable welding numerical models, authors must consider the welding process parameters, geometrical constraints, material non-linearities and all physical phenomena involved in welding, both thermal and structural. In this sense, four different premises are taken into account. Firstly, all finite elements corresponding to the deposition welding are deactivated and, next, they are reactivated according to the torch’s movement to simulate mass addition from the filler metal into the weld pool. Secondly, the movement of the TIG torch was modelled in a discontinuous way assuming a constant welding speed. Thirdly, the arc heat input was applied to the weld zone using volumetric heat flux distribution functions. Fourthly, the evolution of the structural response has been tackled through a stepwise non-linear coupled analysis. The numerical simulations are validated by means of full-scale experimental welding tests on stainless steel plates. Finally, the results and conclusions of this research work are exposed.