Comparing thermal stimulation techniques in infrared thermographic inspection of corrosion in steel

Abstract

Remote detection of corrosion in metals is a developing application area of active thermal nondestructive testing. In this study, emphasis is made on the optimization of heating techniques that is of a major interest in practical surveys. Some popular data processing techniques, such as Fourier transform, correlation and principal component analysis, are also quantitatively compared in application to corrosion detection in 1-2 mm thick steel by applying a criterion of signal-to-noise ratio. The best inspection results have been obtained by using powerful halogen lamps and air blowers. Material loss of about 25 % with lateral dimensions greater than 10x10 mm can be reliably identified in practical tests. The use of Xenon flash tubes is inefficient because of significant steel thickness. LED panels have not provided expected results due to low absorption of LED quasi-monochromatic radiation.