Inductive thermography is a non-destructive inspection technique. The sample is heated with a short heating pulse and an IR camera records the surface temperature, which is then evaluated to a phase image by Fourier transform. The technique can be well applied for detecting cracks in metals. Additionally, it has also the advantage of providing information about the depth of the crack. Larger contrast is an indication of deeper cracks, while small contrasts refer to shallow cracks. Therefore, the phase contrast can be used to make an estimation of the considered crack. In order to investigate these capabilities, short cracks (length =0.3-3mm) were created in Inconel 718 welded samples by a Varestraint test machine. The samples were then inspected with inductive thermography, computer tomography (CT) and by fluorescent penetrant test (FPT). The crack lengths obtained by all the three methods are compared. The dependency of the phase contrast on the crack depth and length is then analyzed in comparison to the CT results. Finally, additional finite element simulations were carried out and compared to the experimental results.
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