Inverse Transformation in Eddy Current Tomography with Continuous Optimization of Reference Defect Parameters

This paper presents a methodology of inverse tomography transformation in eddy current tomography with the use of continuous optimization of reference defect parameters. Ferromagnetic steel samples with rectangular air inclusion defects of known dimensions were prepared and measured using an eddy current tomography setup. FEM-based (Finite Element Method based) forward tomography transformation was developed and utilized in inverse tomography transformation. The presented method of inverse tomography transformation is based on the continuous optimization of parameters that can describe the sample, such as the diameter and dimensions of the reference defect. The obtained results of inverse tomography transformation were in high accordance with the real parameters of the samples. Additionally, the presented method had acceptable repeatability. The obtained values of the sample parameters fit within the range of expanded uncertainty when compared to the real parameters of the sample.

An Overview of Non-Destructive Testing of Goss Texture in Grain-Oriented Magnetic Steels

Grain oriented steels are widely used for electrical machines and components, such as transformers and reactors, due to their high magnetic permeability and low power losses. These outstanding properties are due to the crystalline structure known as Goss texture, obtained by a suitable process that is well-known and in widespread use among industrial producers of ferromagnetic steel sheets. One of the most interesting research areas in this field has been the development of non-destructive methods for the quality assessment of Goss texture. In particular, the study of techniques that can be implemented in industrial processes is very interesting. Here, we provide an overview of techniques developed in the past, novel approaches recently introduced, and new perspectives. The reliability and accuracy of several methods and equipment are presented and discussed.

Optimization of the electrical technology complex for high-performance induction heating lines

The paper discusses the design issues of a high-performance induction installation for heating ferromagnetic billets before processing on deforming equipment. Specific features of the technological process of heating ferromagnetic billets to plastic strain temperatures are noted. It is shown that in order to increase the efficiency of the process, the heating of large-sized preforms from ferromagnetic steel is advisable to be carried out in a two-frequency induction heater with two autonomous sections. A study of the heating process in a two-section heater of ferromagnetic billets was carried out taking into account the nonlinear dependence of the physical characteristics of the heated billets metal on the temperature changing during heating. The problem of minimizing the length of a two-section heater is formulated and solved taking into account energy and technological limitations. A condition for determining the optimal length of the first section is to achieve a temperature corresponding to the loss of magnetic properties in the layer equal to the depth of current penetration at the frequency of the second section power supply. The results of numerical calculation of the optimal parameters of a two-section heater are presented. It is shown that the power distribution algorithm along the length of a two-section heater is a piecewise constant function. The results of calculating the temperature distribution in the workpieces during heating are presented. The results of the study can be used to solve the problem of optimizing the structural and operational parameters of a multi-section heater.