Induction thermography as a powerful tool to crack detectability and quantification: a feasibility study at consistent scanning speeds

This work investigates the potential of induction thermography for quantitatively assessing surface-breaking cracks under dynamic inspection conditions. Experimental tests were conducted on S355J2 steel specimens with artificial notches of varying depth and length, scanned at a constant speed of 4 km/h. A thermal contrast-to-noise ratio was computed for each crack and correlated with its geometry in terms of length and depth using a power-law calibration, enabling an empirical probability of detection (POD) curve derivation. A Finite Element Model (FEM) was used to simulate the electromagnetic-thermal response and physically interpret the contrast variation with depth. The results demonstrate the feasibility of depth and length quantification under motion and support induction thermography as a fast, non-contact method for both crack detection and characterisation in industrial environments.