Evaluation of Welding Defects with X-ray Digital Laminography for NDT inspection of Carbon Steel Plate

Abstract

X-ray imaging Digital Laminography (DL) is a well-known Non-Destructive Testing (NDT) technique well suited for non-destructive examination of large and flat structures where traditional Computed Tomography (CT) is impractical. This technique provides 3D radiographic imaging and precise characterization with depth information of welding defects in welded components, ensuring component quality meets the standard criteria and safety purposes. Furthermore, determining the welding defect's location in fabrication, in-service, and maintenance is crucial for welding repair, resulting in the areas where the repair work needs to be started. This work highlights the characterization of welding defects by experimental digital radiographic testing (RT-D) and digital laminography (DL) techniques applied to welded carbon steel plates. A test specimen, specially prepared with artificial linear and volumetric flaws like lack of fusion, clustered porosities, and slag inclusions with varying dimensions, was tested, and the approaches were analyzed. Furthermore, a test phantom was fabricated with known geometry features that access the DL system's optimal detection accuracy to demonstrate a broad functionality and acceptance of the DL system for depth information in flat and plate structures. The digital laminography technique provides advantages for characterizing welding defects and testing phantom features with high contrast and acceptable image quality. The result is then confirmed by the advanced Ultrasonic Testing (UT) and RT-D. To ensure compliance with industry standards in RT-D, the exposure conditions, image sensitivity, and quality are analyzed according to ISO 17636-2.