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A European consortium consisting of four major steel manufacturers and ten academic technology institutes has conducted a research and development project, called “Product Uniformity Control“ (PUC) in the period 2013 to 2017. This project aimed to develop and improve non-destructive (inline) measurement techniques to characterise the (uniformity of the) microstructure of steel strip products. In this project, a multitude of strip steel samples from various stages of production have been collected from the four participating steel manufacturers. The samples have been characterised in various ways, namely on their (1) non-destructive measurement parameters using different techniques suited for inline evaluation, (2) fundamental ultrasonic and electromagnetic properties (wave speed, ultrasonic attenuation, magnetisation loops, coercive field), (3) tensile properties (stress-strain curves) and (4) microstructure (by optical micrographs and EBSD images). The correlations between these different characterisations will be addressed. Besides the experimental characterisation, a strong accent has been on modelling activities: during the project, fundamental models have been developed to describe, starting from 2D and 3D microstructures, the ultrasonic and magnetic properties, which are next used as input to sensor models that predict the output of the inline measurement systems. This contribution will present the recent results of both the experimental and the modelling work, and underline their mutual importance in the interpretation of the measured data for the benefit of inline characterisation of the mechanical properties complementary to traditional destructive tensile testing.

International audience; Two numerical techniques, the finite integration technique (FIT) and the surface integral equation (SIE) method are combined with the semi-analytical calculation of the field in planar conducting pieces in order to calculate the interaction of such specimens with ferrite-cored eddy-current probes. Coupling different techniques allows us to chose the best suited for each part of the configuration and to better exploit the existing symmetries.

Eddy current testing signals are quite sensitive to the probe tilt, which is difficult to adjust in many practical testing configurations. In order to take account of this effect in simulation, a collaborative work between CEA and the University of Western Macedonia has been carried out. This paper presents the modeling approaches that have been used for the primary field computation and its interaction with the flaw, respectively, as well as an experimental validation of the complete model available in the CIVA software.