Corrigendum to “Grain size evaluation with time-frequency ultrasonic backscatter” [NDT E Int 117 (2021) 102369] (NDT and E International (2021) 117, (S0963869520303716), (10.1016/j.ndteint.2020.102369))

A few production errors were found since the publication of the article. The original Fig. 6 in the Journal Pre-proof file was incorrectly replaced by the original Fig. 7 in the final version. As a consequence, the original Fig. 7 was incorrectly replaced by the original Fig. 8 as well. The correct Figs. 6 and 7 should be shown as follows. [Figure presented] Fig. 6. The influence of transducer focal length and element diameter calibration on Euclid distance between SVS and the experimental variance surface. [Figure presented] Fig. 7. S^T of key material parameters at different frequencies and times in the time-frequency model. The authors would like to apologise for any inconvenience caused.