Combination of numerical and physical simulations as a new approach to the evaluation of the K-TIG welding process of thick duplex steel plates

Duplex stainless steels, known for their resistance to corrosion combined with high yield strength, are increasingly used in offshore structures to reduce weight and material usage. The K-TIG welding process offers a solution to meet growing demands for the high-quality, cost-effective welding of duplex steel. It is a process in which, in contrast to the conventional TIG method, the application of high current intensity results in the formation of the so-called “keyhole” effect, enabling deep penetration even in materials of significant thickness. However, the limited flexibility of K-TIG method for modifying welding parameters for thick plates presents challenges. Moreover, different thermal cycles may occur across the weld thickness. This paper proposes an integrated approach combining numerical and physical simulation to optimize the K-TIG welding method for 10 mm duplex steel plates. A three-dimensional thermal model was developed using COMSOL Multiphysics, simulating the heat transfer and thermal cycles across the heat-affected zone, which was used in physical simulations conducted using a Gleeble 3180 system. The results show that thermal cycles vary significantly across the weld thickness, leading to microstructural differences that could influence the mechanical and corrosion properties of the welded joint. The proposed methodology provides an effective tool for optimizing the K-TIG process, offering insights into thermal cycles, microstructure evolution, and overall weld quality in thick duplex steel plates.