PSI - Issue 59

Liubomyr Poberezhnyi et al. / Procedia Structural Integrity 59 (2024) 158–166 Liubomyr Poberezhnyi et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Isolation of specimen surface by nail polish layer. Advantages of this technique – the possibility of choosing an arbitrary shape of the working electrode. It allows for the easy creation of a model representing groups of defects to simulate their interaction. This technique proves useful for conducting OCP measurements for heat-affected zone (HAZ), which has a width of just 1 mm. Disadvantages of this technique – preparation time (6-12 hours), crevice corrosion may occur 5-6 hours after the initial potentiodynamic measurements. A new coating is required for each test. 2. Building a clamp-on electrochemical cell (Fig. 1, a, b) Advantages of this technique – the electrochemical cell is reusable. Quick installation time (5-10 min). No need to isolate all specimen surfaces. No risk of crevice corrosion. Disadvantages of this technique – the area and shape of the working electrode always remain consistent, and there is a requirement to construct a new cell when altering the parameters related to the working area. It is difficult to install on the samples with a thickness of less than 6-7 mm.

Fig. 1. Specimen and equipment for electrochemical test: (a) electrochemical test stand; (b, c) clamp-on cells, (d) test specimen with welded joint (WJ). Potentiodynamic polarization tests were performed in the three-electrode cell with a working area of 0.196 and 0.5024 cm 2 and scan rates of 0.5; 0.25; 0.125 mV/s to investigate its impact on the corrosion processes. The development of the COMSOL model for the corrosion of a welded joint is proposed to be carried out in two stages: 1. Corrosion modeling of a welded joint considering the different electrochemical activity of its sections (Fig. 2, a). This stage involves determining corrosion currents and calculating the corrosion rate based on these data. 2. Similar to step 1, with modeling of the anti-corrosion coating (Fig. 2, b, c).