Non-Invasive Detection of Hidden Corrosion in Aluminum Sheets

Abstract

Non-invasive detection of hidden defects using infrared thermography (IRT) mainly focuses on defects involving material loss. Of equal importance is the detection of hidden defects resulting from corrosion. This study proposes an improved method of detecting hidden defects caused by corrosion through active IRT. Aluminum sheets with or without hidden corrosion were identified using two simple analysis approaches, (1) observing differences in their mean surface temperature and visual thermal contrast and (2) comparing the temperature probability distribution of identified surfaces at a given reference temperature. The developed method only requires heating the region of interest to <66 °C with a portable heat source and monitoring the surface temperature distribution using IRT. This method may aid in building surveys and post-monitoring of metallic building envelopes, especially indoors or when environmental conditions cannot provide the needed thermal contrast for detecting hidden corrosion.