Pulse-Inversion Chirp-Coded Weld Harmonic Imaging (PI-CWHI) of Friction Stir Welded Butt-Joint

M. Tabatabaeipour, J. Hettler, N.T. Sewell, J.R. Wright, J. C. S. Wright, S. Delrue, K. Van Den Abeele

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


The microscopic size and the closed characteristics of zigzag line defects at the root of friction stir welded joints frequently result in a detection inability by off-the-shelf ultrasonic weld inspection techniques. To overcome this problem, we take advantage of a non-linear ultrasonic approach by employing a slanted contact pitch-catch mode scanning using chirp-coded excitation with subsequent pulse-inversion analysis. We validated that the observed nonlinearity correlates well with the micro-crack density along the weld path. Doing so, hot spots in the pulse-inversion chirp-coded weld harmonic images can be interpreted as zones with high concentrations of micro-flaws.
Original languageEnglish
Article number75 (2017)
Pages (from-to)1-10
Number of pages10
JournalJournal of Nondestructive Evaluation
Early online date23 Oct 2017
Publication statusPublished online - 23 Oct 2017


  • Friction stir welding
  • Micro-crack density
  • Zigzag line defects
  • Continuous oxide film
  • Pulse-inversion
  • Chirp-coded sccitation
  • Harmonic imaging
  • Non-destructive testing


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