TY - JOUR A1 - Kidangan, R. T. A1 - Unnikrishnakurup, Sreedhar A1 - P. Vengara, N. A1 - Balasubramaniam, Krishnan A1 - Rajagopal, P. A1 - Phani Prabhakar, K. V. A1 - Padmanabham, G. A1 - Riedel, F. A1 - Puschmann, M. T1 - Online monitoring of cold metal transfer (CMT) process using infrared thermography N2 - Online (passive) thermographic inspection of overlap joints of aluminium and zinc coated steel sheets made by cold metal Transfer weld brazing process was explored. Different experimental Trials were conducted for demonstrating the feasibility of thermographic inspection to detect the porosities, improper weld bead and to differentiate the pre weld temperature. The whole process was monitored using infrared cameras in different wavelength region. Image analysis algorithms were developed to reconstruct the thermal images that contain the signatures of the weld defects and to extract the pre weld temperature and ist evolution with distance from the centre of the weld torch. Post-weld radiography lends strong Support to the observations. KW - Infrared thermography KW - Dissimilar joints KW - Online monitoring KW - Cold metal transfer process PY - 2016 DO - https://doi.org/10.1080/17686733.2016.1229330 SN - 1768-6733 SN - 2116-7176 VL - 14 IS - 1 SP - 68 EP - 78 PB - Taylor & Francis AN - OPUS4-38910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unnikrishnakurup, Sreedhar A1 - Kidangan, R. T. A1 - P. Vengara, N. A1 - Balasubramaniam, Krishnan A1 - Rajagopal, P. A1 - Phani Prabhakar, K. V. A1 - Padmanabham, G. T1 - Application of infrared thermography technique for the monitoring of cold metal transfer (CMT) joining of aluminium to galvanized steel N2 - In this study, the feasibility of using non-contact Infrared thermography as a potential tool to monitor the CMT welding process is explored. The presence of internal defects such as porosity, lack of filler material deposition and formation of improper weld bead produce perturbations in the surface temperature which can be identified using an Infrared thermography technique. We present recent results obtained from online monitoring of the the dissimilar joining using CMT weld brazing of Aluminum and Steel using a transmission mode measurement approach. The effect of loss of zinc coating on the weldability of the cold metal transfer joining of aluminum to galvanised steel was investigated. A correlation between measured online thermal indications with the weld anomalies is successfully attempted and the results are compared with the conventional post-weld NDT inspection methods. T2 - 19th World Conference on Non-Destructive Testing (WCNDT 2016) CY - Munich, Germany DA - 13 June 2016 KW - Infrared thermography KW - CMT welding KW - Weld defects KW - Online monitoring PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-389155 UR - http://ndt.net/?id=19475 SN - 1435-4934 VL - 21 IS - 7 SP - 1 EP - 8 PB - NDT.net CY - Kirchwald AN - OPUS4-38915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unnikrishnakurup, Sreedhar A1 - Myrach, Philipp A1 - Polomski, Benjamin A1 - Le Claire, Elisabeth A1 - Vengara, N. A1 - Balasubramaniam, Krishnan A1 - Ziegler, Mathias T1 - Thermographic crack detection in hot steel surfaces N2 - The detection and characterization of surface cracks in steel specimens prior to damage is a technologically and economically highly significant task and is of utmost importance when it comes to safety-relevant structures. In steel production where steel billets at high temperatures have to be inspected while moving a number of well-established NDT methods cannot be applied. Laser thermography however is a promising candidate to serve as a fast, non-contact and remote tool in this case. We present a study that shows that the crack detection capabilities of laser thermography can be extended also to specimens at high temperature. A combination of inductive and laser heating allows to systematically study the contrast formation as well as the optimization of the important measurement parameters. The experiments are accompanied by FEM simulations that provide a better insight of the physical correlations and support the experimental developments. The aim of these studies is to develop a system with high inspection speed and detection performance to be in-line operated under the hostile environment of steel production lines. T2 - 19th World Conference on Non-Destructive Testing (WCNDT 2016) CY - Munich, Germany DA - 13.06.2016 KW - In-line Monitoring KW - Laser Infrared thermography KW - Cracks KW - Induction heating KW - Steel billets KW - FEM simulation PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-389161 UR - http://ndt.net/?id=19573 SN - 1435-4934 VL - 21 IS - 7 SP - 1 EP - 8 PB - NDT.net CY - Kirchwald AN - OPUS4-38916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -