Volume 37, Issue 3 (May 2009)
Ultrasonic Imaging Technique of Spot Weld Structure for a High Strength Galvanized Steel Sheet
In this paper, ultrasonic C-scan imagery technique is applied to measure the nugget diameter and image the defects in a spot weld of a high strength galvanized steel sheet. In order to enhance the test precision, the ultrasonic C-scan image is divided into six characteristic color regions and the related A-scan signals are analyzed according to the structural characteristics of the high strength galvanized steel spot weld. The results indicate that the nugget diameter can be measured accurately, and the shape of inner defects of nugget is evaluated based on the C-scan image and the time domain analysis of A-scan signal. The method proposed in the research is not only a comprehensive and visualized method for spot welding evaluation, but also a kind of important auxiliary method for spot weld research since the inner structure of the spot weld can be investigated without devastating it.