PSI - Issue 72

Aria Pranata et al. / Procedia Structural Integrity 72 (2025) 383–391

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including pitting, intergranular corrosion, and stress corrosion cracking (SCC). These effects are compounded by mechanical stresses, which accelerate crack initiation and material failure. While tropical and acidic environments cause the most severe degradation, innovations like corrosion inhibitors (e.g., ethylene glycol) and optimized alloy compositions can mitigate damage, enhance mechanical properties, and extend the service life of structural components in harsh maritime conditions. These findings underscore the importance of corrosion control strategies in maintaining the integrity and durability of patrol boat materials. 4. Material degradation due to welding Material degradation caused by welding joints in aluminum alloys presents a significant challenge in patrol boat construction, particularly due to the exposure of materials to aggressive marine environments. Research by Wan et al. (2021) revealed that optimizing weld geometry can enhance the mechanical properties of TIG-welded joints in 2219 T8 aluminum alloy, commonly used in maritime applications. By employing multi-pass TIG welding with swing techniques, the researchers enhanced the tensile strength and elongation, achieving a strength coefficient of 70% and an elongation of more than 4% compared to the base metal. Key weld geometry parameters, including the penetration depth of the capping weld, front weld width, and reinforcement height, were optimized through a combination of numerical simulations and experiments. The swing welding process effectively reduced strain variation and stress concentration at the weld toes without significantly affecting the microstructure or microhardness. Fig. 4 illustrates the macroscopic cross-sections and tensile properties of optimized joints produced using three-pass TIG welding with swing techniques in the final pass. The optimized weld geometry demonstrates smooth transitions, minimizing stress concentration areas. Tensile tests revealed improved mechanical properties, with an ultimate tensile strength (UTS) of approximately 316 MPa and elongation values of 4.8% and 5.6%, meeting the target of a 70% joint strength coefficient and elongation above 4% (Wan et al., 2021).

b

a

Fig. 4. Macroscopic cross-section and tensile properties of the optimal joints (a) elongation 4.8%; (b) elongation 5.6% (Wan et al., 2021).

The study by Sheng et al. (2024) examined the impact of welding parameters, joint geometry, and internal defects on the overall tensile response of AA6061-T6 welded joints. Using welding parameters of 2.40 kW laser power and a travel speed of 1.27 m/min, the research produced welded joints with superior tensile properties, including higher tensile strength and more uniform axial deformation compared to other parameter sets. Results from finite element modeling (FEM), digital image correlation (DIC), and micro-CT revealed that void size significantly affects stress concentration and failure potential, while smaller, dispersed voids have minimal impact on tensile response. This study emphasizes the importance of optimizing welding parameters and controlling internal defects to enhance the mechanical performance of welded joints (Sheng et al., 2024). Further research by Attah et al. (2022) investigated the effects of material placement and tool rotational speed on the tensile strength and hardness of friction stir welded (FSW) joints made from AA7075-T651 and AA1200-H19 aluminum alloys. The study used 6 mm thick aluminum plates welded in a butt joint configuration, with variations in material placement (on the advancing side or retreating side) and rotational speeds ranging from 900 to 2100 rpm.