Micro and macro microstructure modelling for the influence of grain size on magnetic properties in structural steel and modelled commercial sensor outputs

Zhou, Lei; WMG, Warwick University; United Kingdom

Zhou, L.; University of Warwick; United Kingdom
Shen, J.; University of Warwick; United Kingdom
Davis, C.; University of Warwick; United Kingdom
Martinez-De-Guerenu, A.; CEIT; Spain
Jorge-Badiola, D.; CEIT; Spain
Gutiérrez, I.; CEIT; Spain
Kok, P.J.J.; Tata Steel; Netherlands
van den Berg, F.D.; Tata Steel; Netherlands
Labbé, S.; Université Grenoble Alpes; France
Skarlatos, A.; CEA; France
Reboud, C.; CEA, LIST; France
Lombard, P.; ALTAIR Engineering France; France

ID: ECNDT-0228-2018
Download: PDF
Session: Modeling and data processing Electromagnetic Techniques 3
Room: J2
Date: 2018-06-12
Time: 13:50 - 14:10

The mechanical properties of steels are controlled by their microstructural parameters, such as grain size, phase balance and precipitates, which are developed during thermal mechanical processing. It is desirable to be able to monitor microstructural changes during processing, allowing in-situ feedback control, or to characterize microstructure in steel products in a non-contact and non-destructive manner. Electro-magnetic (EM) sensors are now widely employed in the steel industry, for example to monitor phase transformation during strip cooling (EMspec) and strength in cold rolled strip (IMPOC, HACOM, 3MA), where a combination of empirical correlations and fitted models are used. Models have recently been developed to relate the sensor signals to magnetic properties and, separately, to relate magnetic properties to microstructure.
In this work an ultra-low carbon steel sample was used to generate ferrite grain sizes between 2.5 – 80 µm. EBSD data was used to generate 3D voronoi based microstructure models representing the grain structures, which have been used in multi scale magnetic modelling approaches to predict the magnetic properties. Both micro (EMicroM) and macro (COMSOL Multiphysics based) scale models have been developed and applied to determine magnetic hysteresis curves and low field permeability values. These have been compared to experimentally determined hysteresis curves and magnetic parameters. The modelled and, where available, measured magnetic data have then been used in EM sensor (IMPOC, 3MA and EMspec) models to determine sensor sensitivity to grain size measurements.