Indoor accelerated controlled corrosion degradation test of small- and large-scale specimens

Abstract

The work presented here is a part of a long-term project analysing the structural behaviour of ageing marine structures. An accelerated corrosion degradation set-up was developed to reproduce corroded marine structural specimens of different degrees of degradation, controlling various natural factors, i.e., temperature, oxygen content, salinity, and flow velocity. The nine stiffened plates of 1.2 m length and 30 small scale specimens made of mild steel of three different thicknesses have been corroded. The mean corrosion depth and rate have been controlled during the degradation process for all specimens. The corrosion degradation characteristics have been measured and analysed. In the case of small-scale specimens, microscope scanning, and for the stiffened plates, ultrasonic thickness measurements were performed. The obtained corrosion surfaces are highly non-uniform. During the corrosion degradation, a number of measurements were performed to satisfy a confidence level of 95% and an error of 10%. The developed corrosion degradation is compared with a real corrosion depth measurement of ship deck plates of ballast and cargo tanks, showing a very good similarity in the trend and the corrosion acceleration, concluding that the developed corrosion degradation controlled experimental set-up is efficient in reproducing marine structural specimens of different degree of degradation for further mechanical testing.