Corrosion morphology and penetration in high-strength structural steels characterized by X-Ray tomography and mass-loss measurem

https://doi.org/10.3221/IGF-ESIS.79.12

Mass-loss measurements provide a global measure of corrosion damage but do not capture extreme localized penetration. This study compares CT-derived maximum localized penetration with mass-loss-derived equivalent average penetration for S460, S690, and S960 structural steels subjected to three controlled 5% salt-spray exposure regimes. X-ray computed tomography was performed on one specimen per steel-grade–exposure combination, while gravimetric measurements were obtained from four comparable specimens per condition. The novelty lies in directly comparing localized CT descriptors with replicated global mass-loss data under common exposure conditions. Maximum localized penetration ranged from 97.5 to 724.2 µm, whereas equivalent average penetration ranged from 16.3 to 49.7 µm. The results show that CT and gravimetric measurements describe different aspects of corrosion damage and should not be used interchangeably. A corrosion localization index was used only as a supplementary maximum-to-average penetration ratio. Combining both descriptors may improve durability assessment where average mass loss underrepresents severe localized penetration.