COR-TEN steel: atmospheric corrosion behavior by accelerated ageing

The present work therefore focuses on Cor-Ten corrosion behaviour when exposed to stagnant or runoff conditions, by means of both accelerated ageing tests (alternated immersion or dropping tests, respectively) and natural exposure tests. The latter were carried out in urban seaboard environment (Rimini, Italy), close to a monitoring station where microclimatic parameters are recorded and gaseous pollutants and atmospheric depositions periodically analysed. Also the influence of surface finishing conditions used in architecture/sculpture was considered, by testing commercial bare or pre-patinated Cor-Ten sheets, with and without a beeswax coating. The corrosion behaviour of the patina and its evolution were studied by electrochemical measurements (Open Circuit Potential, OCP, Polarization Resistance, Rp, and Polarization Curves, PC) and microstructural analysis (Scanning Electron Microscopy with EDS probes and X-ray Diffraction). The release of Fe, Cu, Cr, Mn and Ni was followed through Atomic Absorption Spectrophotometry as a function of exposure time. The results showed that pre-patination, with or without beeswax coating, has no beneficial effects on corrosion and confirmed the unsatisfactory behaviour of bare steel in stagnation conditions, with a consequent higher metal release compared to leaching conditions.