TY - GEN A1 - Myrach, Philipp T1 - Online Laser Thermography for the Detection of Surface Cracks in Hot Steel N2 - The detection and characterization of surface breaking cracks in steel prior to damage is a technologically as well as economically important task especially for safety-relevant structures. Detection of small cracks already during the steel production process might significantly reduce the risk of failure and reduce production costs due to an obsolete post-processing. However, the hostile environmental conditions (high temperature specimens) together with very strict requirements in current steel production (production speeds, in-line testing and evaluation) are challenging and render many well-established NDE techniques hardly applicable. We present an approach to use laser thermographic testing as a fast, remote and contactless NDE method, that addresses these challenges and might ultimately allow for online crack detection. The basic idea of laser thermographic testing, introduced by Kubiak in 1968, is the monitoring of the heat flow as induced by local heating. Disturbances within the heat flow generated by the presence of surface cracks can then be analyzed by image processing algorithms, as we have shown in previous work. The aim of the presented work is to advance laser thermographic testing to be applicable to the specific conditions of steel production environments. This purpose was met by the development of a laboratory setup that allows us to simulate production conditions, as rolling speed, specimen temperature, laser heating power and study their influence on crack detection performance. This parametric study enabled us to develop and improve data processing and crack detection algorithms with the final goal of providing optimized in-line crack detection. The studies were accompanied by comprehensive FEM simulations to intensify the understanding of the contrast formation as well as the crucial parameters influencing the performance of the method. T2 - QNDE 2017 CY - Provo, UT, USA DA - 16.07.2017 KW - Thermography KW - Cracks KW - Crack detection KW - Laser thermography KW - Laser-thermographic testing KW - Steel PY - 2017 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/42924 AN - OPUS4-42924 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany