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With excellent mechanical properties because of strain-induced martensitic transformation (SIMT), applications of austenitic stainless steels can be extended to a further broad range of engineering fields. In order to discover applications from a clarification of their mechanical properties, especially at higher deformation rate, it is important to evaluate an amount of martensite, which can control such excellent performances of the steels during deformation. However, until now, it is quite hard to find experimental studies for the evaluation during deformation at various strain rates. In the past, volume resistivity and impedance have been measured during deformation. However, these studies have not been successful to evaluate it with a higher precision. Instead of those, it is useful to measure directly relative magnetic permeability, which has a correlation with the amount of martensite, because of focusing on a ferromagnetic characteristic of martensite. In this study, at first, SUS304, which is a kind of austenitic stainless steels, is deformed plastically under tension at various strain rates. Then, it is attempted to evaluate the amount of martensite during deformation by measuring the relative magnetic permeability expressing ferromagnetism directly. Finally, the strain and strain rate sensitivity of SIMT in the steel is discussed by obtained results. [ABSTRACT FROM AUTHOR]

An ultra-low carbon grain-oriented silicon steel as-cast strip is produced by twin-roll strip casting process, and subsequently subjected to one-pass hot rolling, one-stage cold rolling, primary annealing, and secondary annealing. The effect of hot rolling process on microstructure, texture, and inhibitor evolution is studied. It is shown that the precipitation behavior of AlN particles is significantly affected by the hot rolling temperature and the optimal precipitation temperature is ≈1100 °C. On the other hand, the intensity of Goss texture in hot-rolled sheets is determined by hot rolling reduction, which is limited in the strip casting process and the hot-rolled Goss texture is relatively weak compared to the conventional process. The primary annealed Goss texture can originate from the cold rolling process and this texture is homogeneous through the thickness, besides the inherited hot-rolled Goss texture mainly presented in the subsurface layer. Thus, relatively strong Goss texture in primary annealed sheets is obtained. The results indicate that the hot rolling process is an efficient way to optimize the texture and precipitation in strip-cast silicon steel, and relatively good magnetic properties can be obtained by the strip casting process. [ABSTRACT FROM AUTHOR]

SUMMARY The accurate magnetic properties of electrical steel sheets are important for the development of high-efficiency electromagnetic devices. In particular, the H-coil method is a useful technique for accurately measuring magnetic field strength in a single sheet tester. Therefore, we developed a tester for magnetic field properties using the H-coil method, referred to as the stress load type single sheet tester (S-SST), and a problem was found in iron loss measurement at a high flux density of 1.6 T or more. In this paper, it is shown that the cause of this problem is the phase difference between the induced voltage in the H-coil and the B-coil. Because the phase difference makes the B-H loop slightly twisted near the tip point, the iron losses are evaluated low. Thus, we propose a method of determining the phase correction values. These values are measured in the absence of a specimen in the S-SST measurement system, and the phase correction method for induced voltage in a coil is investigated. Finally, ideal results for the correction of iron loss in nonoriented electrical steel sheets are shown. The proposed method is effective for the calibration of a single sheet tester using the H-coil method. [ABSTRACT FROM AUTHOR]

The influence of stresses on the magnetic properties of nonoriented electrical steels was studied. The dependence of iron loss on compressive stress was affected by grain size. The magnetic polarization J in strong magnetic fields such as 5000 and 10,000 A/m increased due to compressive stresses and decreased due to tensile stresses in samples with low Si content. Using Kerr-effect domain observation, it was found that the reduction in J caused by tensile stresses was attributable to residual striped domains. Magnetostriction measurements in strong magnetic fields indicated that the increase in J under compressive stresses originated from the Villari effect (inverse magnetostrictive effect) due to negative magnetostriction in low-Si materials. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(4): 10-18, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22320 [ABSTRACT FROM AUTHOR]

This paper presents the measured magnetostriction of electrical steel sheets under alternating magnetic flux conditions. In the measurements, we used a two-dimensional vector magnetic property measurement system, and a three-axial strain gauge. In order to know the magnetostriction in an arbitrary direction, the strain tensor was evaluated. In addition, we try to evaluate the magnetostrictions in the thickness direction. In this paper, the three-dimensional magnetostriction in nonoriented and grain-oriented silicon steel sheets are compared. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(4): 1-9, 2012; Published online in Wiley Online Library (). DOI 10.1002/eej.21257 [ABSTRACT FROM AUTHOR]

The two-dimensional vector magnetic properties are proposed as a method to express the magnetic anisotropy and iron loss precisely by using the relationship between the flux density vector and the magnetic field strength vector. The E&S modeling [6] and the E&SS modeling [7–9] have enabled the representation of the two-dimensional vector magnetic properties in FEM calculations. However, the calculated flux density waveform at each element has a phase difference depending on the excitation condition. In this paper, we have improved the E&SS modeling to solve the magnetic field problems under any exciting condition. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(1): 1–9, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20446 [ABSTRACT FROM AUTHOR]