Novel non-destructive technique for detecting the weld fusion zone using a filler wire of high x-ray contrast

Non-destructive testing (NDT) of welded aluminium (Al) joints for quality assessment is of great importance to the automotive industry, among others. Currently, no post-process NDT technique can differentiate between the fusion zone and substrate for typical welded Al joints, thereby preventing measurement of crucial quality metrics such as weld penetration. X-ray Computed Tomography (CT) and x-ray radiography are two common NDT techniques used to evaluate internal discontinuities in welds. A novel method that provides contrast between the Al substrate and weld fusion zone in x-ray images is demonstrated. The post-process technique relies on incorporation of a dopant element in the filler wire with a greater x-ray attenuation coefficient than the substrate, demonstrated here through incorporation of Cu in the filler wire for gas tungsten arc welded (GTAW) Al joints. This novel grayscale contrast in the post-process x-ray images enables the detection of penetration depth and weld throat, which cannot be differentiated when using conventional filler wires. Composition maps of the joint cross sections are compared with the post-process x-ray scans to further examine this technique.

Automated summary

This study demonstrates a novel method that provides contrast between the Al substrate and weld fusion zone in x-ray images by incorporating a dopant element in the filler wire with a higher x-ray attenuation coefficient. This technique enables the detection of penetration depth and weld throat more accurately than conventional methods.