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. Introduction The objectives embraced by the entire global community as outlined in the groundbreaking Paris Agreement – aiming to restrict global warming to well below 2°C and to make every effort not to exceed 1.5°C - require a transition to renewable energy sources (RES) within the next few decades (IRENA, 2023). In particular, in order to protect the planet's ecosystems and ourselves from the catastrophic consequences of climate change, humanity must eliminate greenhouse gas emissions from its activities and achieve a negative carbon balance in the second half of the 21st century. This implies that by 2050, transportation, energy, industry, and the general population must completely switch to renewable energy sources, necessitating the preservation of most proven coal deposits, as well as a significant share of oil and gas reserves, in the ground. According to the Annual review 2023 published by IRENA (IRENA and ILO, 2023), wind and solar power are going to play a significant role in the global electricity sector. The report presents various scenarios for the development of the energy sector until 2050, and the analysis shows that there is a growing consensus on the increasing importance of wind power in the energy mix in the coming decades. IRENA experts predict that onshore and offshore wind generation could supply more than one- third (35%) of the world’s electricity demand by 2050 (COP28 et al, 2023). This highlights the significance of increasing the share of wind power in the energy system for its decarbonization. Corrosion can degrade the structural material, contribute to fatigue cracking (Nykyforchyn et al, 2019; Syrotyuk et al., 2021), brittle failure (Maruschak et al, 2014, Kryzhanivskyy et al, 2019; Leshchak et al., 2020), and unstable failure (Melchers, 2005, Momber et al, 2015), and the integrity of the entire structure can be significantly compromised (Poberezhny et al, 2019, Okipnyi et al, 2020). Corrosion problems in offshore wind power facilities significantly contribute to operation and maintenance costs, typically around 15 – 30 percent of the total life cycle costs (Tusar & Sarker, 2022). In the literature, there are many numerical simulations of the growth of pits and cracks in seawater under the influence of mechanical loads (Katona et al, 2021, Zvirko, 2021, Zhang et al, 2022). The primary limitation of these studies is their failure to consider the variation in the equilibrium potential of the structural component of the welded joint. This oversight results in the formation of a multi-electrode electrochemical interaction. This study aims to develop a methodology for numerical modeling of corrosion processes within the welded joint zone and the electrochemical interaction of metal surfaces in areas with insulation defects. 2. Methodology For theoretical and experimental studies, S355J2 steel (table 1) was chosen, which is widely used in the construction of bearing elements of wind power facilities.

Table 1. Chemical composition of the S355J2 steel. Percentage by weight % max.

Si

Mn

P

S

Cu

Fe

C

0.025

0.55 >97

0.20 0,55 1.60 0.025

Specimen preparation. The surface of the specimen (Fig. 1, d) was thoroughly prepared with sandpaper 600 at least 12 hours before the electrochemical test and cleaned with acetone immediately before the test. All specimens were numbered and marked. The working sides of the samples were photographed and marked «a», «b», «c» and «d». Electrochemical test technique. Electrochemical tests were conducted in 3.5% NaCl solution, serving as simulation of seawater. The reference electrode (RE) employed was the Ag/AgCl (Sat'd KCl) electrode and the counter electrode was made from stainless steel mesh. Open Circuit Potential (OCP) measurements and potentiodynamic polarization were carried out with a Gamry Interface 1010B. Two techniques were used for constructing electrochemical cells: