Calibration of thermographic spot weld testing with X-ray computed tomography. Issue 1 (2nd January 2017)

• Record Type: Journal Article
• Authors: Myrach, Philipp; Jonietz, Florian; Meinel, Dietmar; Suwala, Hubert; Ziegler, Mathias
• Is Part Of: Quantitative infrared thermography. Volume 14:Issue 1(2017)
• Page Start: 122
• Page End: 131
• Publication Date: 2017-01-02
• Subjects: Thermographic testing -- spot weld -- spot weld testing -- computed tomography -- non-destructive testing; Infrared technology -- Periodicals; Thermography -- Periodicals; Infrared technology; Thermography; Periodicals; 621.362
• DOI: 10.1080/17686733.2017.1281554
• Languages: English
• ISSNs: 1768-6733

Abstract

Abstract: The paper presents an attempt for the calibration of an active thermography method that is suitable for the non-destructive evaluation of spot welds. Nowadays, the quality of spot welds is commonly characterised by the application of random chisel tests, which are time consuming, expensive and destructive. Recently a non-destructive testing method by means of active thermography was proposed that relies on the fact that the mechanical connection formed by the spot weld also serves as a thermal bridge between the two steel sheets joined in the welding process. It is shown in this paper that this thermal bridge can be thermographically characterised by extracting a measure for the spot weld diameter and hence the quality of the spot weld. The determination of the absolute value of the diameter hereby relies on a calibration of the testing system, which is performed by means of X-ray computed tomography in this study. The experiments were carried out using different experimental approaches, namely transmission as well as reflection geometry wSetup in reflectionith laser illumination. A comprehensive evaluation of samples produced using different welding currents, hence different quality, was carried out in order to validate the thermographic results.