Quantification of Localized Water Image in Under-Film Corroded Steel with High Spatial Resolution, High Time Resolution, and Wide View by Neutron Radiography

Abstract

Information on the existence of localized water at corrosion locations is indispensable for precisely understanding the corrosion mechanism in steel. Small amounts of localized water in under-film corrosion have not yet been measured quantitatively.

Although we have demonstrated that neutron radiography, which has high sensitivity to the presence of hydrogen, is suitable method for detecting of water in the under-film corrosion of painted steel by utilizing the RIKEN Accelerator-driven Neutron Source (RANS), the spatial and time resolutions were insufficient to investigate under-film corrosion in detail. We then performed an imaging experiment on localized water in steel corrosion with higher space and time resolutions using the high-intensity neutron source at J-PARC. We obtained data with a spatial resolution of 0.6 mm, a time resolution of 15 s in a viewing area of 100 × 100 mm². On the basis of the results for the quantitative imaging of localized water in corrosion, we have established a method suitable for directly imaging water in steel corrosion that employs neutrons.

Fig. 4 Changes in water distributions with time.