Nondestructive Eddy Current Array (ECA) technique for Stress Corrosion Cracking (SCC) detection and assessment

Many structures and mechanical components are under a combination of loading (stresses) and some kind of corrosive environmental operational condition which is called Stress Corrosion Cracking (SCC). Tubes in cooling water services, geothermal, and nuclear equipment are among the equipment which are subject to SCC. Since the SCC occurs at stresses within the range of typical design stress, it can cause catastrophic failures without a significant indication in structural integrity beforehand. Efficient Nondestructive Inspection (NDI) during the operational life of the structures can prevent such failures by providing accurate information regarding size and characteristics of the SCC flaws. Since majority of SCC defects occur in surface and near surface regions of metallic components, electromagnetic NDI (Eddy Current) is proved to be a promising inspection technique. In this study, Eddy Current Array (ECA) methodology was used for assessment of SCC generated in steel samples in a laboratory setup. ECA as an advanced eddy current NDI uses an array of eddy current coils to provide the scanning image of the inspection area. Prefabricated notches and SCC after a period of load-corrosion application to the samples were detected and characterized. Accuracy and repeatability of the results showed the efficiency of ECA for SCC characterization.