Non-destructive inspection of hidden corrosion through Compton backscattering technique

The purpose of this study is to investigate the hidden corrosion at selected sites in corrosion simulated Mild Steel using information from the Compton scattered gamma rays. The proposed non-contact method employs a 137Cs source and an HPGe detector as part of the practical framework and it is integrated with the MCA system. The scattered gamma rays reflecting the corrosion is mapped in real time during the scanning of the specimen. Point by point scanning is carried out to acquire the pulse height spectrum and datas are used to determine the thickness of a known test object and hence thickness calibration is attained. With the calibration as a basis, hidden corrosion at the sub surfaces is detected and analysed. A reconstruction algorithm is explicated for this proposed work with a good precision of corrosion quantification in the subsequent layers. The precision is comparable with the radiography and transmission results. Experimental measurements and their results strongly confirm hidden corrosion to a depth of 4 mm (with a range of corrosion from 1.76 mm to 2.29 mm) in Mild Steel could be detected.