Corrosion Analysis of Helical Electrodes

ABSTRACT Low‐voltage electrode steam boilers are core pressure‐bearing equipment for clean heating. However, the observed asymmetric corrosion of helical electrodes remains mechanistically unclear, which cannot be explained by existing studies on V‐shaped electrodes in hot water conditions. In this work, the premature corrosion failure of S30408 helical electrodes after 3 months operation was investigated via material characterization and COMSOL simulations. The electrical simulation reveals pronounced geometry‐induced nonuniformity in the calculated current density distribution, with stronger electrical loading on the concave surface and near the electrode edges, where the local value reaches approximately 6.2 × 10 4 A/m 2 . Surface profilometry shows broad, shallow depressions (maximum measured depth approximately 2.1 × 10 2 μm). Flow‐field calculations further show local streamline convergence and recirculation on the concave side, which may reduce liquid renewal and favor retention of steam bubbles generated during boiling. The combined effects of non‐uniform electrical loading and local hydrodynamic conditions provide a plausible explanation for the asymmetric surface attack.