The Corrosion Performance of Aluminized Steel with Coating Defects Exposed to Natural Waters

Abstract

Aluminized steel is a common material used in the production of corrugated drainage pipes that are used to allow water flow under roads and sidewalks. During fabrication, hot-dipped aluminized steel sheets are mechanically formed into a cylindrical pipe shape in which metal dyes or rollers are used to form the corrugations to increase structural capacity. Additionally, the edges of the sheets are linked together in an interlocking fashion to provide a sturdy seam. The plastic deformation of aluminized steel results in coating deficiencies which has been shown to result in premature corrosion of the substrate steel. Depending on the exposure conditions, the service life of the pipes may be significantly reduced.The objective of this work is to determine the corrosion performance at coating deficiencies generated within the lock seams of aluminized steel drainage pipes. Previous work addressing the corrosion of aluminized steel has primarily focused on the cut edge where the ratios of coating to substrate material is minimal. This work presents experimental results of long-term exposure studies with detailed analysis of corrosion morphology as well as local galvanic activity distributions at defect locations using the scanning vibrating electrode technique (SVET). Additionally, crevice corrosion cells are set up to monitor corrosion activity within small gaps indicative of the space within the lock seams. Results are compared between artificially defected and as-received cases for mild and aggressive solutions of simulated natural water. A finite element model capable of simulating the corrosion progression for various lock seam geometries and exposure conditions will also be presented.