Reconstruction of size and depth of simulated defects in austenitic steel plate using pulsed infrared thermography

In this paper the size and depth (distance from the tested surface) of defects in austenitic steel were estimated using pulse infrared thermography. The thermal contrast calculated from the surface distribution of the temperature is dependent on both these parameters. Thus, two independent experimental methods of defect size and depth determination were proposed. The defect size was estimated on the basis of surface distribution of the time derivative of the temperature, whereas the defect depth was assessed from the dependence of surface thermal contrast vs. cooling time.