Integrated experimental and thermo-mechanical investigation of temperature distribution and tensile failure mechanisms in dissimilar stainless steel 304–carbon steel welds

The mechanical performance and long-term reliability of dissimilar metal welds are critical for engineering structures subjected to complex loading and environmental conditions. This study presents a combined experimental and finite-element simulation approach to investigate the thermal behavior, microstructural evolution and tensile failure mechanisms in welds between austenitic stainless steel 304 and carbon steel. Welding was performed using flux-cored arc welding (FCAW) with a 1.2 mm electrode at 130[Formula: see text]A, 26[Formula: see text]V and a travel speed of 350[Formula: see text]mm/min, yielding an energy input of 0.58[Formula: see text]kJ/mm under CO 2 shielding. The temperature field during welding was modeled with a moving Goldak double-ellipsoid heat source, predicting peak temperatures of 1350 ∘ C at the fusion boundary and mapping residual stress distributions along the Ox and Oy directions. Microstructural analysis revealed significant phase transformations within the carbon steel heat-affected zone (HAZ), including martensite and bainite formation, resulting in local hardness peaks of 620 HV, contrasting with 210–230 HV in the base stainless steel. Scanning electron microscopy confirmed the presence of [Formula: see text]-ferrite and stable austenite in the weld metal, contributing to its high mechanical stability. Tensile testing demonstrated that failure occurred exclusively within the carbon steel HAZ, consistent with finite-element predictions, where the combination of high residual tensile stresses and brittle microstructural phases initiated crack propagation. This work establishes quantitative correlations between welding parameters, thermal cycles, microstructural evolution and mechanical response, providing actionable insights for optimizing welding procedures and enhancing the reliability of dissimilar metal joints in critical applications such as shipbuilding, pressure vessels and structural engineering.