Corrosion detection in mild steel using effective post processing technique for modulated thermal imaging: A numerical study

Active thermography is a promising non-destructive testing technique for defect detection in any solid material. It is a fast, secure and contactless imaging technique. It uses thermophysical properties of material produces different thermal contrast for the defective and non-defective areas. In this paper, we utilized the capability of active thermography to detect corrosion which is a common problem in mild steel. We use digital-modulated excitation i.e. Digital frequency-modulated excitation (DFM) at Mild steel samples that contain whole and; corrosion as a defect. Further post-processing Fourier transform, correlation coefficient and time-based phase schemes are used to enhance the detection capability. We also calculate the signal to noise ratio (SNR) of these schemes and compare them. From this analysis, we found that correlation coefficient and time phase can be better post-processing schemes.