Comparative analysis of hull steel corrosion in tropical marine atmosphere: Correlation between indoor simulations and outdoor exposures

• A comprehensive investigation into the differences in corrosion behavior between indoor and outdoor environments. • The rust layer on outdoor samples exhibited superior protective properties compared to that on indoor samples. • The GM (1, 1) models were developed to accurately predict the corrosion trends in both indoor and outdoor tests. • Grey relational analysis revealed a strong correlation between corrosion in indoor and outdoor environments. Corrosion, a complex and gradual process, is best studied by directly exposing the materials to natural environments that closely mirror real-world conditions. However, this approach has limitations due to its lengthy testing periods and excessive costs. As an efficient alternative, laboratory-based accelerated corrosion tests provide a means to predict the corrosion behavior and service life of materials under long-term outdoor exposure. Current simulation tests often focus on correlating weight loss data between indoor and outdoor environments. However, they may overlook the need for a thorough examination of corrosion behavior across various conditions. This study systematically investigates the corrosion behavior of hull steel in a tropical marine atmospheric environment through a combination of indoor simulation and outdoor exposure tests. The research comprehensively analyzes the correlation between indoor and outdoor corrosion, conducting detailed examinations of the corroded materials with a focus on the properties of the rust layer. The results demonstrated a strong correlation between indoor and outdoor corrosion. However, the outdoor specimens exhibited superior protective properties, characterized by a denser rust layer, higher α/γ* ratio, lower i corr, and higher R p . Furthermore, models capable of accurately forecasting samples’ behavior in indoor and outdoor environments were developed by using the GM (1, 1) method. The significance of this study lies in its comprehensive revelation of the differences between indoor and outdoor corrosion tests. It provides valuable insights for developing more accurate and dependable corrosion prediction models, which can optimize corrosion protection strategies for materials in marine environments.