The Approach to the Evaluation Criterion of the Sample Length (Solid and Granulated) Aiming at Getting Information on the Magnetic Properties of its Material

The article considers the approach in which such a criterion value regarding the length λ= [λ] of the investigated cylinder sample is set, when the self-similar field (“plateau”) of magnetic properties, in particular, induction <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$B$</tex> begins. In this case due to vanishingly small demagnetizing factor the defined magnetic properties of the sample correspond to the sought properties of its material. The research in the field of different intensity <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$H$</tex> with the use of solid steel (steel 40X, analogue in the EU - steel 37Cr4, λ= 1,1…50, H = 5,2…127 kA/m) and granulated samples (steel 95X18, analogue in the EU - steel 1.4125, λ= 1…13, H = 14…131 kA/m) were conducted. The authors propose to determine the value [λ] having based on the principle of piecewise-linear approximation, but adapting it to the specific coordinates (logarithmic and semi-logarithmic). In this approach the ascending nonlinear region of the obtained λ- dependency of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$B$</tex> can be approximated by both power-law (for the solid sample) and logarithmic functions (for the granulated sample) which displays this area as “linear” (quasi-linear) in corresponding coordinates. Then the value λ = [λ] is determined at abscissa of its intersection with interpolated line of tail self-similar field, i.e., by specific dependency “break point” <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$B$</tex> on λ. The article provides criterion values λ= [λ] for each sample type well as functional H-deoendencies of [λ].