Article Article
Automated Non-Destructive Evaluation of Spot Welds using the Imaging Analyses of the Residual Magnetic Flux Density

Resistance spot welding is due to its high reliability and economy one of the most widely used welding methods in the automotive and railway industries. The high-quality assurance requirements in these areas call for reliable nondestructive testing (NDT) methods of the spot welds. The nugget is localized between the sheet metals and therefore not directly measurable from outside. This aspect continues to pose a major challenge for non-destructive quality assurance, especially due to the increasing diversity of used steel alloys in car body manufacturing. At the Technische Universität Dresden, Germany, the imaging analyses of the residual magnetic flux density has been developed for NDT of spot welds. Up until now, the manual evaluation of the measurement results is timeconsuming and subjective. In order to achieve greater reliability and to minimize evaluation times, an algorithm for automated evaluation has been developed. In order to evaluate the quality of the algorithm, the results are compared with NDT and destructive measurements of the same samples. For these samples, typical automotive steel combinations for spot welding were used. This paper will show the measuring concept of the imaging analyses of the residual magnetic flux density for NDT of spot welds and presents the high potential of using an automated non-destructive evaluation algorithm for NDT of spot welds.

DOI: 10.32548/RS.2019.013

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