PSI - Issue 82

Goran Vukelić et al. / Procedia Structural Integrity 82 (2026) 3– 8 Vukelić et al./ Structural Integrity Procedia 00 (2026) 000–000

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1. Introduction Additively manufactured metals, especially stainless steels, are gaining prominence in critical marine applications such as marine engineering, offshore structures, and underwater systems (Bogdanovic and Ivosevic, 2025; Brdar et al., 2025; Ermakova et al., 2019; Polemis and Boviatsis, 2023). Despite the considerable potential of AM, its integration into industrial practice often requires welding, either to assemble multiple AM parts or to join AM materials with conventionally manufactured (CM) components (Mokhtari et al., 2021). Welding of additively manufactured metals presents distinctive challenges that are particularly pronounced when joining AM components to CM materials, where differences in thermal and mechanical properties can introduce stress concentrations, cracking, and other weld related defects (Braun et al., 2023). In addition to this, the marine environment poses further challenges due to its highly corrosive nature (Dantas et al., 2024). Although stainless steels generally exhibit excellent resistance to uniform corrosion, they remain susceptible to localized corrosion phenomena, such as pitting, crevice corrosion, and stress corrosion cracking, under prolonged seawater exposure (Ettefagh et al., 2021). Corrosion-induced material degradation can have severe implications for the structural integrity of offshore platforms, marine propulsion plants, and related systems (Kopic and Mihaljec, 2025). The corrosion behavior of AM stainless steels may differ from that of their conventionally manufactured counterparts, owing to variations in surface morphology, residual stress distribution, and microstructural characteristics inherent to the additive process (Monkova et al., 2024). Furthermore, welded joints in AM components often represent critical sites where localized corrosion and mechanical degradation can initiate and propagate more rapidly (Rzeszotarska et al., 2023). Therefore, understanding the combined effects of welding and marine exposure on the mechanical and corrosion behavior of AM stainless steels is vital for their safe and effective deployment in maritime and offshore applications (Malíková et al., 2024). This study presents an experimental investigation into the influence of natural marine exposure on the properties of welded additively manufactured stainless steel AISI 316L. Three types of welded specimens were fabricated: AM AM joints, AM-CM joints, and CM-CM joints serving as reference samples. The specimens were immersed below the sea surface in the Adriatic Sea for durations of one, three, and six months, respectively. Following exposure, the samples were evaluated for changes in mass and tensile strength. 2. Materials and methods AISI 316L steel butt-welded specimens were immersed below the sea surface for exposure durations of one, three, and six months to evaluate the influence of the natural marine environment on their corrosion behavior and provide better insight into the corrosion effects than laboratory tests (Hoque and Presuel-Moreno, 2025). Upon retrieval, the specimens were examined for relative mass changes over time to quantify corrosion-induced material loss, with results correlated to the respective exposure periods. Standardized testing procedures were employed to obtain engineering stress-strain curves from uniaxial tensile tests, enabling assessment of changes in tensile strength. The mechanical test results are presented as a function of exposure duration. The study was performed on AISI 316L stainless steel, referred to as marine-grade stainless steel (Hamada et al., 2025). Primary alloying constituents are chromium, nickel and molybdenum, Table 1.

Table 1. Composition of conventionally manufactured (CM) and additively manufactured (AM) feedstock powder AISI 316L, based on supplier datasheet (w t %). C Cr Ni Mo Mn Si P S AISI 316L CM 0.03 17.3 13.4 2.5 1.8 0.7 0.04 0.03 AISI 316L AM 0.03 17-19 13-15 2.25-3 - - - -

To prepare the specimens for testing, conventionally manufactured (CM) and additively manufactured (AM) AISI 316L stainless steel plates were fabricated, each measuring 210×90×2 mm. The AM plates were produced using Laser Powder Bed Fusion (PBF) technology on an EOS M280 system. The stainless steel powder had a particle size distribution between 10 and 40 μm. During printing, the plates were built in a flat orientation and subsequently shot-