Development and deployment of online multifrequency electromagnetic system to monitor steel hot transformation on runout table of hot strip mill

This paper presents a simulation and experiment study on an electromagnetic (EM) sensor system for monitoring the phase transformation of steel strip on the runout table (ROT) of the hot strip mill in Tata Steel IJmuiden. The sensor head contains an H shaped magnetic core and is excited simultaneously at multiple frequencies. A simulation study linking the output of the EM system, in the form of a mutual induction spectrum, to the transformation processes within the steel strip is presented. This is performed by linking the results of thermodynamic models of the transformation behaviour of the steel strip (modelled with the TITAN mill model, property of Tata Steel) with the EM response of the sensor system (modelled with Ansys Maxwell 3D). The simulations are able to show the induction spectra that would be measured for a particular mill set-up and steel strip at different positions over the length of the ROT. The paper further describes the construction and deployment of the sensor head on the IJmuiden hot strip mill and presents the first results from this type of system with data taken during normal production on the mill. © 2014 Institute of Materials, Minerals and Mining.