PSI - Issue 79

A. Bacco et al. / Procedia Structural Integrity 79 (2026) 335–341

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and, hence, characterized by different physical and thermal properties, such as thermal conductivity, specific heat capacity and density. Whenever the bead elements are activated at the liquidus temperature, they are supplied with energy in the form of heat, considered as internal energy generation. The heat spreads within the system according to the imposed boundary conditions, namely convection and radiation, which significantly influence heat distribution and dissipation, and, consequently, the development of the observed thermal profile.

Fig. 1. Temperature distribution during passes [°C]

The mechanical analysis enabled the evaluation of the effects induced by the thermal gradients arising during the welding process, which manifest as residual stresses in the material. Specifically, longitudinal and transverse residual stresses were evaluated along two distinct paths: a transverse path across the weld bead, positioned at the mid-length of the joint (Figures 2a-b), and a longitudinal one coinciding with the central axis of the joint (Figures 3a-b). The analysis of residual stresses along the transverse path highlighted that the two materials exhibit distinct responses to the thermal gradients induced by welding. This behaviour is attributable to the specific mechanical and thermal properties of each material, which affect the distribution of internal stresses and their residual intensity after cooling. These observations are fundamental to understand the mechanical response of the welded joint and to optimize the process parameters in order to minimize residual stresses and improve the overall quality and durability of the welded component.

a