Detection of defects in a welded joint by scanning contact potentiometry

Scanning contact potentiometry (SCP) is a nondestructive method used for defects detection, and for determining the location coordinates of defects in welded joints. This paper evaluates the accuracy of SCP method in detecting defects and localising them in welded steel plates. The effectiveness of the SCP method was evaluated using sample of steel 321 H plates (Chromium–Nickel–titanium stainless steel), where sample plates were welded by means of manual arc welding, dimension of each 200 × 110 × 13.5 mm. After welding, welded sample was inspected using an X-ray radiographic testing system. In order to investigate SCP capabilities, plotted potentiograms were compared with the corresponding X-ray radiograph image. Furthermore, SCP signals were analysed using discrete Fourier transform. Experimental outcomes proved that defects can be detected by SCP technique more accurate comparative to X-ray. Also it is considered an inexpensive comparable to X-ray and ultrasound non-destructive testing methods. As a result, SCP may substitute some destructive or non-destructive testing methods.