Use Of Pulsed IR Thermography For Determination Of Size And Depth Of Subsurface Defect Taking Into Account The Shape Of Its Cross-Section Area

Abstract

Abstract The paper is devoted to reconstruction of size and depth (distance from the tested surface) of artificial defects with square and rectangular cross-section areas using the pulsed IR thermography. Defects in form of flat-bottom holes were made in austenitic steel plate. The defect size was estimated on the basis of surface distribution of the time derivative of the temperature. In order to asses the depth of defects with considered geometries on the basis of calibration relations (i.e. dependence of time of contrast maximum vs. defect depth for given defect diameter) obtained for circular defects, the ‘equivalent diameter’ describing not only the defect cross-section area but also its shape was assigned. It has been shown that presented approach gives satisfactory results.