Issue 78

G. Palomba et alii, Fracture and Structural Integrity, 78 (2026) 233-247; DOI: 10.3221/IGF-ESIS.78.14

hardness-strength correlations, and FE simulations, with the scope of modelling local stress-strain curves for AISI 316L welded joints. Tensile tests and digital image correlation were employed to experimentally validate the results, thus provide a complete, efficient and cost-effective procedure for mechanical characterization of welded components, based on minimally-destructive inputs. Hence, the present work addresses the development of an integrated and validated experimental-numerical methodology for AISI 316L welded joints, combining hardness mapping, hardness-property correlations, finite element modeling, and preliminary DIC validation. The specific contribution of this work lies in the application of hardness-derived local constitutive modelling to welded AISI 316L butt joints, combined with FE implementation and DIC-supported assessment of the resulting strain-field heterogeneity. This approach contributes to the goals of sustainable design and structural safety, within the PRIN 2022 PNRR project EMPATHY, by providing a development path for a reproducible method for non-destructive assessment of local mechanical behavior in welded marine structures. Material and welding procedure he welded joints were made using a qualified welding procedure (WPS 08/24) in compliance with EN ISO 15609 1:2020. A full-penetration butt joint was prepared on a 3 mm ASTM A312 TP316L stainless steel plates (Group 8.1). The joint was realised with a single-V groove shape with a 60° angle, a root face of 1–2 mm, and a root opening of 0–1 mm, using manual gas tungsten arc welding (GTAW/TIG). Filler metal ER316L with a 2.4 mm diameter was used. The thoriated tungsten electrode (WT20, Ø 2.4 mm) operated with direct current electrode negative (DCEN), at a current range of 50–60 A and voltage of 18–21 V. The welding speed ranged among 50 and 55 mm/min, using 0.39–0.81 kJ/mm of heat. Shielding was provided by high-purity argon, with flow rates of 9–12 L/min. Before starting the welding process. initial cleaning was performed by grinding and brushing between passes. No post-weld heat treatment (PWHT) was applied. The welding was executed by certified personnel using standard conditions. After that, the excess overfill at the weld cap was mechanically removed to obtain a flat surface. This procedure ensured uniform geometry and prevented stress concentrations during mechanical testing. The specimens were obtained using laser machining according to ASTM E8/E8M-24, with the weld centerline aligned transversely (perpendicular) to the longitudinal loading axis of the tensile dog-bone specimen. Fig. 1 shows the characteristics of dog-bone specimens and the configuration used for welding. T M ATERIALS AND METHODS

(a)

(b) Figure 1: Geometry (a) and welding configuration (b).

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