Papers by Keyword: Electrical Steel

Abstract: Grain-oriented electric steel is hot rolled at different hot rolling temperature, and subsequent thermal maintained. Precipitation features of MnS and Cu₂S were observed under different process conditions using thermal field emission scanning electron microscopy. The results show that Cu is precipitate out in the form of a composite precipitate with MnS during hot rolling, The hot rolling temperature and the postrolling maintain time had no obvious effect on the precipitation of MnS, The lower the hot rolling temperature, the faster the Cu₂S precipitation. And the insulation process after high temperature hot rolling can make a large number of the Cu₂S diffusion precipitation, There was no significant effect on the precipitation of Cu₂S after low temperature hot rolling, still remain in the precipitate state after hot rolling.

Abstract: This study investigated the effects of carbon addition on the development of deformation and recrystallization textures in 3 mass% Si steels cold-rolled by 95% reduction in thickness. A 3% Si steel with 0.016 mass% carbon developed RD // <110> (α-fiber) cold-rolling texture to a much greater extent than a 3% Si steel containing carbon less than 0.0005 mass%, whereas it is well known that the development of α-fiber rolling texture is suppressed by the addition of carbon in steels without silicon. This unique effect of carbon addition in the 3% Si steel appeared to be originated from a change in active slip systems. Straight slip bands were observed in the specimen without carbon, and the active slip plane was identified as {110}. On the other hand, wavy slip bands were observed in the steel containing carbon resulted from the activation of {112} and {123} slip planes in addition to {110}. It was also observed that {411}<148> recrystallization texture developed in the carbon-bearing 3% Si steel. Since the recrystallized grains with {411}<148> orientation preferentially nucleated in the vicinity of highly-strained deformation bands formed in deformed grains having α-fiber orientations, it is concluded that the development of {411}<148> recrystallization texture was resulted from the formation of the α-fiber texture after heavy cold-rolling in the carbon-bearing 3% Si steel.

Abstract: We applied eddy current transducer (ECT) to examine the electric steel parameters. The research topic is considered relevant due to the need for evaluation and forecasting of safe operating life of electric steel products. A scheme that uses a computer as a generator and receiver of signals from windings is proposed. Having the designed transducer as a basis, a hardware-software complex was built to perform experimental studies of steel at the interface boundary. The article provides the key technical information about the eddy current transformer used and describes the methodology of measurements that makes it possible to control steel to dielectric transition. Test results are reported for a specimen with continuous and discrete measurements taken at different frequencies. The curve of introduced voltage amplitude as a function of sensor location was constructed to study in details the introduced voltage drop at the ferromagnetic-dielectric interface. Presentation of induced voltage changes in the form of mathematical dependences enables to elicit the ways of interaction between electromagnetic field of eddy-current converter and residual magnetic field of steel.

Abstract: The present study, which is based on the finite element method, investigates the alloy element content assessment of these Fe-Si alloy steel sheets from the view point of eddy current testing. The relative permeability and conductivity were preset parameters. Eddy current signals were gathered by a differential type cylindrical probe and subsequent nondestructive tests were carried out with the preparation of four Fe-Si alloy steel sheets with different silicon contents. The result of the numerical simulation demonstrated that the signal increased with the increase of the silicon content in the Si-Fe alloy steel sheets. And the measured result confirmed the rationality of the application of eddy current testing in the average silicon content assessment.

Abstract: The magnetostriction and magnetic properties of electrical steel are depended on the external stress. In this paper, a noncontact magneostriction measuring system using laser displacement meter with high resolution of 10 nm has been built. The grain-oriented electrical steel with dimensions 500 mm × 100 mm × 0.3 mm was measured between 20 MPa and-20 MPa. The magnetostriction and magnetic properties were highly sensitively to stress. A clear relationship between power loss and magnetostriction under stress was found, and the underlying mechanism has been discussed.

Abstract: The water-based paint had been examined to prepare a new chromate-free insulating coating on silicon steels. The structure of the insulating coating was characterized by scanning electron microscopy, energy dispersive spectroscopy and infrared spectroscopy. Adhesion, high temperature annealing, and surface insulating resistance were measured. Corrosion resistance was investigated by neutral salt spray test and electrochemical test. Results exhibited that the insulating coating had excellent comprehensive performance. The adhesive level was 5B degree; the high temperature annealing test showed no coating degradation after heat treatment of 2 h at 450 °C in air or at 750 °C in nitrogen; the salt spray test showed the corrosion area was less than 2 % after the 12 h salt spray; when the coating thickness was 1.0-1.2 μm, the surface insulating resistance value was 380-420 Ω/mm².

Abstract: The microstructure development in cold rolled electrical steel under dynamic heat treatments was subjected to investigation. Significantly distinguish types of microstructures were obtained in the investigated steels confirming the different character of grain boundary motion. Application of annealing temperature within two phase region (austenite+ferrite) leads to abnormal grain growth in silicon steels. Moreover, in the optimum temperature range, there was a particular temperature leading to the most optimal microstructure and texture[1]. The effect of Si content on the phase transition temperature of the electrical steel (0.6, 1, 2.5, 2.9 % Si) was studied by using differential scanning calorimetry (DSC) analysis. The result indicated that DSC analysis could be used to detect the shift temperature of phase transformation in the electrical steel with different Si addition. DSC have been used in thermochemical studies and as complementary to the study of phase transformation. It can be used as a compliment to optical and electron microscopy.

Abstract: Electrical steel sheets play an important role in magnetic circuit core design of electrical machines. Electrical steel are graded depending on value of specific total loss (P_S). According to the present knowledge the P_S loss consists of three components: hysteresis loss and both classical and additional eddy current loss components. Magnetic properties depend on direction of magnetization i.e. magnetocrystalline anisotropy. The determination of the specific power loss separation of electrical steel sheets in different direction to rolling direction have been performed using non-standard single sheet tester. Specific total loss was separated into hysteresis, eddy current and excess loss components. The relationship between the hysteresis and additional loss components and the magnetic anisotropy was analyzed. The aim of this paper is to provide a contribution to the better understanding of specific total loss in electrical steel with Goss texture.

Abstract: FeSi steels with and without addition of Al are widely used as electrical steels. To improve the knowledge of the effects by the addition of Si and Al on the hardening and softening under hot rolling conditions, the behaviour of the flow curves in a wide range of temperatures and deformation velocities have been studied.

Abstract: The influence of Tungsten Insert Gas (TIG) and Plasma welding on the microstructure, mechanical and magnetic properties of non-oriented electrical steels is presented and evaluated. Samples of sizes of 5.5 cm x 5.5cm x 2.0 mm were prepared from stock plate, installed on the welding table and welded at welding speeds and pulsed currents following a predesigned protocol. The samples microstructure was studied using SEM after standard mechanical grinding and polishing procedures. The characterization of the samples is concluded with microhardness tests and magnetic measurement (Barkhausen Noise) on TIG and Plasma welded joints in order to investigate the influence of welding on the magnetizing behavior of a high Si-alloyed grade of non-oriented electrical steel.