Особенности фазового состава и структуры доэвтектоидной стали, проявляющиеся в поведении намагниченности вблизи магнитного насыщения

Investigation of the temperature evolution of magnetization curves near magnetic saturation makes it possible to extract new information on the features of the phase composition and structure of hypoeutectoid steel. It is shown that the main contribution to the magnitude and the temperature behavior of the energy density of the local magnetic anisotropy of hypoeutectoid steel is due to the lamellar structure of pearlite. The peculiarity of the temperature behavior of the energy of the magnetic anisotropy, along with the behavior of the paraprocess, indicates the formation of Mn-substituted cementite in the studied steel sample. The observation of the crossover of power-law regularities in the approximation of magnetization to saturation indicates the formation of two-dimensional nano-inhomogeneities of the local axis of easy magnetization in the plates of alpha iron, which are part of the pearlite.

Simulations of the Behaviour of Steel Ferromagnetic Fibres Commonly Used in Concrete in a Magnetic Field

The efficiency of fibre reinforcement in concrete can be drastically increased by orienting the fibres using a magnetic field. This orientation occurs immediately after pouring fresh concrete when the fibres can still move. The technique is most relevant for manufacturing prefabricated elements such as beams or columns. However, the parameters of such a field are not immediately apparent, as they depend on the specific fibre reaction to the magnetic field. In this study, a numerical model was created in ANSYS Maxwell to examine the mechanical torque acting on fibres placed in a magnetic field with varying parameters. The model consists of a single fibre placed between two Helmholtz coils. The simulations were verified with an experimental setup as well as theoretical relationships. Ten different fibre types, both straight and hook-ended, were examined. The developed model can be successfully used to study the behaviour of fibres in a magnetic field. The fibre size plays the most important role together with the magnetic saturation of the fibre material. Multiple fibres show significant interactions.

Operation Characteristics of Adjustable Field IPMSM Utilizing Magnetic Saturation

This paper describes an interior permanent magnet synchronous motor (IPMSM) based on a new adjustable field method. The proposed PM motor achieved magnetic field control utilizing magnetic saturation. In this paper, a back electromotive force (e.m.f.) measurement test and a load test using the prototype motor were conducted to clarify if the proposed motor had a wide operation range. In the back e.m.f. measurement test, it was confirmed that the proposed motor had a wide magnetic field controllable range of 51.7%. In addition, it was revealed, through the load test, that the proposed motor had a wide operating range, including both low-speed high-torque and high-speed low-torque driving conditions. Moreover, based on electromagnetic field analysis, the magnetic field control performance of the proposed adjustable field method was compared with the conventional field weakening control and other adjustable field methods. As a comparison result, it was verified that the proposed motor had less copper loss for the magnetic field control and fewer losses in the high-speed operating range.

Reduction of Core-loss in the High Frequency Band of the Fe-Si-Cr Crystalline Alloy According to Particle Size

In order for soft magnetic composites (SMCs) to achieve the high-performance requirements expected of them even at high frequencies, high permeability and low core-loss are required. In this study, we used different sizes of gas atomized Fe-Si-Cr alloy powder to produce SMCs, this alloy has higher resistivity than existing materials used in SMCs such as Fe-Si alloy or pure Fe. These powders were prepared by sieving raw materials which had an average size from less than 25 µm to over 63 µm. Our experiments show that as particle size decreases, the magnetic saturation tends to increase, the sample made from the powder with particles 25-38 µm in size recorded the highest magnetic saturation of 169.38 emu/g. Additionally, as particle size decreased, permeability increased. The sample made from powder with particles under 25 µm had a permeability of 20.7 H/m at 1 MHz. Also, the relationship between particle size and quality factor was found to be inversely proportional. Finally, the minimum core-loss was 187.26 kW/m3 at 1 MHz for the sample made from powder whose constituent particles are under 25 µm. We also observed that the core-loss is proportional to particle size.