Neutron Radiographic Detection of Corrosion

Many nondestructive testing (NDT) methods for corrosion detection depend on the reduced thickness of the component following corrosive attack. This is normally the underlying concept for corrosion detection by NDT methods such as X-radiography, ultrasonics, and eddy currents. For neutron radiography, however, the basis for the detection is the neutron attenuation by the hydrogen in the corrosion product itself. This difference in the approach gives neutron radiography an advantage over many other NDT methods because of the potential for early detection of corrosion, before extensive attack and thinning of the material have occurred. Neutron radiographic methods are reviewed and some initial results are given for corrosion detection in aluminum. Practical neutron sources are becoming available and can be combined with established image detectors, including real-time detection systems. Corrosion in aluminum resulting from a 6.5-h supersaturated salt-water spray is shown to be detectable.