Cor-Ten in marine atmosphere: the influence of the environment on corrosion

E. Bernardi1, S. Raffo1, C. Chiavari2, C. Martini3, L. Nobili1, M.C. Bignozzi4, I. Vassura1

1 Department of Industrial Chemistry - University of Bologna, Viale Risorgimento 4, Bologna, elena.bernardi@unibo.it

2 Interdepartmental Center for Industrial Research “Advanced Applications in Mechanical Engineering and Materials Technology”, Viale Risorgimento 2, Bologna

3 Department of Industrial Engineering – University of Bologna, Viale Risorgimento 4, Bologna

4 Department of Civil, Chemical, Environmental, and Materials Engineering – University of Bologna, Via Terracini 28, Bologna

ABSTRACT

Architectural and artistic heritage exposed to environment undergoes spontaneous degradation. Thanks to its atmospheric corrosion resistance and pleasant aesthetical features, Cor-Ten (Weathering Steel) has been increasingly employed for outdoor applications. However, the exposure to aggressive atmosphere (e.g. marine or polluted sites) can significantly influence Cor-Ten performances.

In this work, the behaviour of three kinds of commercial Cor-Ten (untreated, artificially patinated, artificially patinated and waxed) exposed to a coastal environment, in sheltered and unsheltered conditions, is examined. SEM/EDS and Raman investigations were performed on Cor-Ten surfaces and cross-sections to identify the main corrosion products and to study the evolution of the corrosion layer (patina). The corrosion-induced release of alloying metals (Cu, Cr, Fe, Ni, Mn) in runoff waters was also analysed. Chemometrical techniques were applied for the interpretation of experimental data in relation to the different surface finishes and to the environmental conditions. Results highlight the great influence the site and the geometry of exposure have on the composition of corrosion layer. Runoff process, on the other hand, result not related to rain amount but strongly affected by seasonal variations and atypical meteorological events.

Parole chiave/Key-words:

Weathering Steel, Marine/Urban Environment, SEM/EDS, Raman, Metal runoff.