Search

Dynamic response of magnetic hysteresis, magnetic Barkhausen noise and magneto-acoustic emission in a soft ribbon and electrical steels was studied comprehensively. The measurements were performed under controllable magnetization conditions: sinusoidal/triangular waveforms of the magnetic induction and a triangular waveform of the magnetic field. Magnetizing frequency was varied in a wide range: f mag = 0.5 – 500 and 0.5–100 Hz for the ribbon and the electrical steels, respectively. Magnetization amplitude was fixed on a near-saturation level H max ≃ 100  A/m. Barkhausen noise signal was detected by a sample-wrapping/surface-mounted coil and differently filtered. It was found that intensity of the Barkhausen noise rises approximately as a square root function of the magnetizing frequency. Whereas, level of the magneto-acoustic emission follows the hysteresis loss trend with an additional linear term (classical loss component). [ABSTRACT FROM AUTHOR]

Ferritic stainless steels are promising materials for application in interconnects of solid oxide fuel cells (SOFC). The present problems to be solved urgently for using ferritic stainless steels as interconnects are their rapid increase in electrical resistance and the cathode poisoning caused by evaporation of chromia. In the present study, the Ni Fe and NiFe CeO 2 alloy coatings have been electro-deposited onto 430 stainless steels (430SS). During oxidation at 800 °C in air, an outer dense NiFe 2 O 4 layer and an inner protective Cr 2 O 3 layer have thermally grown on the coated samples. The NiFe 2 O 4 layer retards the outward migration of chromium effectively. The addition of CeO 2 reduces the growth rate of Cr 2 O 3 and decreases the number of pores near the oxide scale/alloy interface. Moreover, a higher electrical conductivity has been achieved by the addition of CeO 2 . [ABSTRACT FROM AUTHOR]

Abstract: This research mainly explores the influence of various mixed dielectric fluids on the performance of electrical discharge machining of AISI D2 hardened steels. In this investigation, four types of dielectric fluids such as pure kerosene, kerosene and chromium powder mixed, kerosene and Span‐20 surfactant and the combination of kerosene with chromium powder and Span‐20 surfactant were studied. The obtained results illustrated that the addition of chromium powder and Span‐20 surfactant in the dielectric fluid obtained high material removal rate, low electrode wear rate and good surface finish. The presence of chromium powder will stabilize the gap distance between electrodes which promotes the occurrence of multiple discharges in one input pulse and particle agglomeration is reduced after Span‐20 surfactant molecules cover the surface of debris and carbon dregs in kerosene solution. Combination of kerosene with chromium and Span‐20 surfactant were found significant to improve the effects of carbon accumulation and drag discharge, and reduce unstable concentrated discharge. [ABSTRACT FROM AUTHOR]

Laser direct patterning by multi-beam interference can create structures in the sub-µm regime on a wide variety of materials. As the structuring process relies on the interference of 2 or more coherent beams, the reachable dimension of a single structure can be comparable to the applied laser wavelength and the structure is replicated simultaneously over the whole interference volume. To obtain a stable interference pattern a classic approach namely spot-by-spot is adopted. In this approach, several laser pulses are deposited at each position on tool steel and there is no pulse overlap between two neighbored pulse positions. Since the surface is patterned spot by spot, a typical average processing rate of the spot-by-spot approach for a submicron periodicity on tool steel is 21 mm²/min. Aiming to structuring a large scale surface on tool steel with high efficiency and homogenous morphology, we present a patterning strategy, in which laser pulse are deposited with a constant consecutive pulse overlap. In this paper, two patterning methods and periodic nanostructures fabricated by both methods are investigated. As a demonstrator, a 140×140 mm² area with structural periodicity of 690 nm is fabricated on tool steel by using consecutively overlapped deposition of interfering ultrashort laser pulses. A processing rate of 360 mm²/min can be achieved with a single spot size of 120 µm and laser fluence of 0.42 J/cm2. The productivity of continuous structuring can be enhanced by two orders of magnitude comparing with the classic spot-to-spot approach. In addition, we characterized the local and long range morphological homogeneity of the structured surface by means of quantitative analysis of periodicity and depth of patterned nanostructures. [ABSTRACT FROM AUTHOR]

In this paper, the different temperature dependencies of hysteresis and eddy current losses of non-oriented Si-steel laminations are investigated. The measured iron loss results show that both the hysteresis and eddy current losses vary linearly with temperature between 40 °C to 100 °C, a typical temperature range of electrical machines. Varying rates of hysteresis and eddy current losses with the temperature are different and fluctuate with flux density and frequency. Based on this, an improved iron loss model which can consider temperature dependencies of hysteresis and eddy current losses separately is developed. Based on the improved iron loss model, the temperature influence on the iron loss can be fully considered by measuring iron losses at only two different temperatures. The investigation is experimentally validated by both the tests based on a ring specimen and an electrical machine. [ABSTRACT FROM PUBLISHER]

Texture optimization has always been a challenge to fabricate non-oriented electrical steels (NOES). In the present study, thin-gauge NOES with high permeability was successfully processed using an innovative and convenient twin-roll strip casting process without hot rolling. The relation between the as-cast microstructure, processing route and texture evolution was studied. The results indicated that as-cast strip with coarse grains exhibited strong {100}〈0vw〉 texture and unique {110}〈110〉 component. Annealed sheets processed by one-stage rolling displayed pronounced {111}〈112〉, {223}〈110〉 components and weak Cube and Goss texture. Micro-texture characteristics revealed that {100}〈0vw〉 texture was partially retained from initial grains, and new Cube and Goss substructures were generated within {110}〈110〉 deformed grains during cold rolling. This was responsible for the development of Cube and Goss recrystallization texture. Furthermore, the application of two-stage rolling not only reinforced these two behavior, but also accelerated the nucleation of η grains because of the increased shear bands in cold-rolled sheets. In this manner, an improved texture consisting of dominant η-fiber, weak γ-fiber and optimized magnetic properties (B 50 = 1.72 T, P 10/400 = 14.91 W/kg) were obtained. [ABSTRACT FROM AUTHOR]

The rotors and stators of motors (or generators) as well as the cores of transformers are produced by progressive stamping coupled with stacking. Failure in stacking leads to rotor/stator/core misalignment during winding or loss of lamination after crashes. Proper embossing depth of cylindrical spots and clearance between the punch and die are essential for achieving high-quality lamination. In this work, the proper embossing depth was determined and the effect of the punch/die clearance on stacking quality was investigated. Three electrical sheets with various iron losses (H470, H600, and H1300) were used. The sheet thickness was 0.5 mm. The punch/die clearance ranged from 1% to 4% of the sheet thickness. DEFORM 2D was used for the finite element analysis. The piercing test shows that the proper embossing depths for the H1300, H600, and H470 sheet metals are 0.39, 0.37, and 0.36 mm, respectively. The draft angle of the joined interface increases with punch/die clearance. A small clearance is favorable for the stacking with cylindrical spots. Poor stacking occurs when the clearance is larger than 4% of the sheet thickness. [ABSTRACT FROM AUTHOR]

This work investigates microstructures, precipitates, and mechanical properties in 1Cr low alloy steel undergoing normalizing, quenching, and quenching-tempering treatments. The precipitated phases in these samples were removed by electrolytic extraction and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The precipitates extracted from the normalized and tempered samples were mainly M 3 C cementite, while the major precipitates obtained from the quenched sample were identified as Nb-rich MC carbides. Energy dispersive X-ray spectroscopy (EDXS) semi-quantitatively analyzed the ratios of Fe atoms to Cr atoms in relevant phases, revealing that redistribution of Cr occurred in the tempering process but not in the normalizing or quenching processes. The tempered sample contained M 3 C carbide with a {022} twin plane and a hexagonal M 7 C 3 -type phase. Strength and elongation in the quenched sample were larger than these in normalized sample, but a significant reduction in strength and a dramatic increase in elongation occurred when the as-quenched sample was tempered. [ABSTRACT FROM AUTHOR]

This study presents an application of the swept-frequency eddy current (SFEC) technique for characterization of aging conditions of 5Cr-0.5Mo heat resistant steel by a U-shaped, eddy current probe. An optimal eddy current probe was established and employed to investigate the specimens under different simulated service conditions. Sweep frequencies from 500 to 10,000 Hz were generated to measure the impedance changes using a precision LCR meter. As results, the normalized impedances showed the highest differences in each aging condition at the frequency of 3,200 Hz. Microstructural observations were utilized to give details of the differences in microstructures among aged conditions, which related to the carbide precipitation characteristics of the specimens. In addition, a micro-hardness was tested on the carbide colonies in complement the aged conditions. The results showed that the hardness correlated well to the normalized impedances obtained from the swept-frequency eddy current testing. [ABSTRACT FROM AUTHOR]

In this work a new electrocoagulation reactor with cylindrical geometry using a three-dimensional steel wool anode has been developed. The architecture of the Electrocoagulation reactor is closely related to a filter cartridge, modified in order to contain the electrodes. The complete system includes the Cartridge Type ElectroCoagulation Reactor (CTECR) and its housing. The residence time distribution (RTD) was used as tool to study the flow behavior of the electrolyte within the reactor. The new reactor has been successfully used in the removal of a textile dye (Remazol Red RB 133) working in continuous mode of operation, where the color elimination rate reaches 99%. Moreover, its design allows both an easy replacement of the cartridge when the steel wool anode is consumed, and the collection and storage of the hydrogen generated on the cathode. [ABSTRACT FROM AUTHOR]

The article focuses on use of electrochemical reactor with stainless steel concentric tubes electrode for removal of cadmium from waste water, and talks of cathodic reaction, mass transfer control, and electrolyte flow rate.

The initial stage of contact formation during field-activated/assisted sintering of powders is investigated experimentally and numerically for spherical particles of nickel, steel, and copper. The results of experimental studies of the contact resistance and the neck formation process due to melting/sintering in two- to three-particle systems under a single high-current pulse from a capacitor discharge are compared with results of fully coupled thermo-electrical finite-element simulations. The impact of particle size, contact geometry, and electrical load on the temperature and temperature gradient distribution during the pulse discharge is analyzed numerically for nickel spheres. The influence of the material itself is compared for nickel, steel, and copper systems. [ABSTRACT FROM AUTHOR]

The theoretical and experimental analysis described in this paper demonstrate a simple systematic procedure to determine the contact parameters between a spherical impactor and an elastic half space via impact tests. Two main contact parameters were measured at different velocities of impact, that is the time duration of contact and the maximum normal contact force. A general nonlinear contact model based on power law is used to extract the contact stiffness and frequency of contact resonance from these two main contact parameters. Experimental results were obtained and compared for three steel samples with different hardness numbers and impacted by different sphere diameters of 2.0, 2.5 and 3.5 mm to investigate the limits of elastic deformation. Effect of the used sphere diameter on the contact parameters are shown. The test results show that the adopted model using independently measured material data can predict the contact parameters due to hard sphere impact with elastic half space. The general trend shows the increase of contact stiffness with the sphere diameter but the limits of elastic regime decrease. [ABSTRACT FROM AUTHOR]

In order to study the issues of the main energy-absorbing position configuration in coach-to-car frontal crashes, and using a numerical simulation model of sedan Taurus and medium-sized coach, we evaluate configuration performance by choosing the intrusion deformation and speed of the steering wheel as the parameters. Coach-to-Car frontal crash simulations were developed by three-dimensional explicit finite element analysis software LS-DYNA3D. Through the analysis of the simulation results, we found that configuration performance of the two vehicles could be improved by adding a secondary, 'deputy', energy-absorbing beam (DEB) with type of No20 steel. Then we contrasted and analyzed the test results. The results show that: DEB has a significant impact on solving the frontal crash configuration issues, and also improves the crashworthiness of coach frontal steel energy-absorbing structure. [ABSTRACT FROM AUTHOR]

This review is devoted to an analysis of plasma electrolytic saturation of steel and titanium alloys with light elements (nitrogen, carbon, and oxygen). These technologies have a number of advantages because of the high rates of processes and the low cost of equipment. Electrochemical aspects of the process, which include the formation of a gas-vapor shell, its composition, processes of anodic dissolution, and oxidation and adsorption of a saturating element on the surface processed, are considered. Data of investigations of the mechanism of the release and transport of nitrogen and carbon from the electrolyte into metal are given. [ABSTRACT FROM AUTHOR]

On evaluating the corrosion resistance of concrete, it is frequent to perform electrochemical tests in the so called simulated pore solutions (SPS) to replace tests performed in concrete specimens. Besides, to study the effect of the chloride content in concrete, chloride ions are added to the SPS. However, it is not obvious whether the SPS simulate the electrochemical behaviour of steel in concrete. Another concern is related to the relationship between the chloride content in concrete and the chloride content of a SPS. To investigate this issue a comparison between the polarization curves of steel in mortar and in SPS was performed. It was found that the SPS is not fully representative of the corrosion behaviour of steel in mortar but it yields conservative results. The relationship between the chloride content in mortar and in SPS that yields similar behaviour is not straightforward but depends on the electrochemical parameter considered. [ABSTRACT FROM AUTHOR]

The electrical resistivity is an important parameter describing materials’ ability to conduct electric current. Dry cementitious materials exhibit very high value of the electrical resistivity due to their insulating nature. Indeed, the electrical resistivity of an oven-dried concrete is about 10 9 Ω m. However, it can be significantly decreased by a sufficient amount of electrically conductive admixture. Such an enhancement is beneficial in self-sensing or self-heating concrete design, but it is not convenient in special cases such as design of concrete used for railroad ties production. In this case, mechanical properties (tensile strength) need to be improved without an accompanying decrease of the electrical resistivity. In this paper, reference concrete together with three types of steel-fibre reinforced concrete (0.5% vol., 1% vol., 2% vol.) were prepared and analyzed in terms of determination of electric properties. Experiments were carried out in both, DC and AC electric regime by means of precise DC multimeter and LCR meter measurements. [ABSTRACT FROM AUTHOR]

TiB2 particle-reinforced copper matrix composite is electroformed in copper sulfate on stainless steel plate. The impact of the particle content in electroforming solution on the surface morphology, hardness, and electrical conductivity of the electroformed composite are studied, and the influence of electroforming current density on the effective content of particles in the composite is also analyzed. The results show that when the content of particles in electroforming solution is 25 g/L, the current density is 4 A/dm2, particles in the electroformed composite are well-distributed, and the average grain diameter can be reduced to 20 µm. The microhardness of Cu/TiB2 composite reinforced by particles with diameter of 3 µm is 25% higher than that of electroformed copper, and its conductivity remains 86% of the copper. [ABSTRACT FROM AUTHOR]

Power transformers are designed to operate under pure ac excitation; however, they may be subjected to superimposed dc voltages and consequential offset currents, for example, from geomagnetically induced currents, geomagnetically induced quasi-dc currents, arising from solar activity. To determine the effects of dc offsets, a single-sheet tester was used with a digital excitation signal created with an ac waveform summed with a dc voltage addition and measured with a digital feedback control algorithm to ensure an ideal flux density waveform. Using this method, results with 300% additional dc contribution were able to be measured for results up to B\mathrm{ ac} + B\mathrm{ dc} = 1.9 T. The measurements of grain-oriented 3% Si–Fe show increasing power losses and peak applied magnetic field for peak-to-peak flux densities above 3 T, with a 33% increase in power loss and 500% increase in applied magnetic field for an offset of 25%. [ABSTRACT FROM AUTHOR]

Heavily loaded rolling-sliding concentrated contacts operate often in the mixed lubrication regime. Only a part of the load is carried by the elastohydrodynamic lubricant film. The rest is carried by the contacting asperities. At these spots, temperature and pressure reach very high values and may cause extensive wear, smearing and even scuffing. The surfaces of machine elements made from steel are never 'clean' and 'bare'. Instead, they are covered at least to some extent by reaction layers. These layers play an important role in the load carrying capacity, since they prohibit bare steel to steel contact and in this way they may protect the rubbing surfaces. The need to study them is evident. One major difficulty is that they are built-up and worn-away during operation while the surfaces pass though the contact. Fortunately, their electrical resistance differs significantly from the resistance of steel, giving a possibility to study their behaviour. In the present work, a newly developed measurement equipment, which allows for precise ECR measurements under realistic operating conditions is presented. The concurrent and competitive process of removal and reformation of the reaction layers and the revelation of bare steel surfaces coming directly into contact is clearly demonstrated. [ABSTRACT FROM AUTHOR]

The advantages of trumpet-shaped ladle shrouds (TLS) have been frequently demonstrated over conventional straight-bore ladle shrouds (CLS) with respect to production efficiency and molten steel quality in continuous casting practices. The present study is to shed some lights on why the TLS are better than the CLS design by examining the fluid dynamics and mass transfer using large eddy simulation. The obtained numerical results were validated with particle imaging velocimetry experiments. Flow velocity, deformation, turbulent energy dissipation, and mixing kinetics of tracer were discussed. The results showed that the entering jet of the CLS flowed straight down into the tundish with a relatively high speed (average at 0.710 to 0.815 m/s) and turbulent kinetic energy. However, the trumpet section of a TLS intensified velocity differences, strain rates, and vortices, and promoted an increase on turbulence dissipation rate in the interior of the ladle shroud. The average speed of the entering jet to the tundish was decreased to 0.270 to 0.410 m/s from the 0.708 m/s of the inlet speed. The entering jet from the TLS swung, twisted and well mixed with surrounding fluid in the tundish, and dissipated its kinetic energy. Consequently, the turbulence of the whole flow field as well as the mean skin friction coefficient of tundish wall and the velocity of free liquid surface were reduced. A tracer experiment was carried out to study mass transfer and flow mixing behavior, and the results demonstrated that the use of the TLS increased the plug volume and decreased the dead zone, thereby enhancing inclusion flotation. [ABSTRACT FROM AUTHOR]

The effect of hot band grain size on the development of crystallographic texture and magnetic properties in non-oriented electrical steel sheet was studied. After cold rolling the samples with different initial grain sizes displayed different microstructures and micro-textures but nearly identical macro-textures. The homogeneous recrystallized microstructure and micro-texture in the sample having small grains caused normal continuous grain growth. The quite irregular microstructure and micro-texture in the recrystallized sample with large initial grain size provided a preferential growth of grains in 〈001〉//ND and 〈113〉//ND which were beneficial for developing superior magnetic properties. [ABSTRACT FROM AUTHOR]

This paper develops an approach to evaluate and predict the effect of punching processes upon the performance of switched reluctance motors (SRMs). Punching is a common process for manufacturing of electric motors although the magnetic performance of the electrical steels at the cut edges may degrade. This could then result in a lower motor performance than expected. Annealing can usually restore the material property but it would be costly for production of common electric motors. Therefore, it is useful to compensate this effect in the design of electric motors. In this paper, the damaged range due to punching is modeled and included in the finite-element simulation for the SRMs such that the effect of this damage can be evaluated. The material properties at the cut edges are determined using the techniques developed here. Two SRMs are investigated: one being annealed after punching and the other not before assembly. Test results show that the annealed SRM produces a better performance. The comparison between the simulations and experiments shows that the developed method can be used for analysis of punching effect on motor performance. [ABSTRACT FROM AUTHOR]

We study the influence of long-term operation and high-cycle loading under laboratory conditions on the electrochemical characteristics of low-strength carbon steels. It is established that both cycling and long-term operation decrease the corrosion resistance and strongly affect the electrochemical characteristics of steels. It is also demonstrated that the polarization resistance is a quite sensitive informative parameter for the evaluation of the in-service degradation of steels of gantry cranes. We reveal a correlation between the changes in the impact toughness regarded as a characteristic of brittle fracture resistance and the changes in the polarization resistance, which can be used as basic for the creation of a new nondestructive method of diagnostics of the degradation of steels of gantry cranes after long-term operation. [ABSTRACT FROM AUTHOR]

It is well known that the magnetic properties of electrical steel sheets are influenced strongly by mechanical stress. We have measured the residual stress distribution with an X-ray stress measurement device and clarified not only the tensile and compressive stress but also the shear stress in a rotating machine core. In particular, the influence of the shear stress on the magnetic properties has not previously been reported. We attempt to develop a new system for measurement of vector magnetic properties under shear stress. This paper presents a mechanism for applying shear stress and the measured vector magnetic properties of nonoriented electrical steel sheet under shear stress. These results indicate that the difference in the vector magnetic properties of the nonoriented electrical steel sheets depended on the shear stress. [ABSTRACT FROM AUTHOR]

Soft devices can be bent, stretched, and compressed reversibly, but conventional wires are rigid. This work describes stretchable composites that are easily fabricated with simple tools and commodity materials, and that can provide a strategy for electrical wiring that meets certain needs of soft devices. These composites are made by combining metal wool and elastomeric polymers. Embedding fine (average fiber width ≈25 μm) steel wool (or other metal wools) in a silicone polymer creates an electrically conductive path through the nonconductive elastomer. This composite is flexible, stretchable, compressible, inexpensive, and simple to incorporate into the bodies of soft devices. It is also electrically anisotropic, and shows maximum conductivity along the majority axis of the fibers, but maximum extension perpendicular to this axis. The utility of this composite for creating an electrically conductive path through an elastomer was demonstrated in several devices, including: a soft, solderless breadboard, a soft touch sensor, and a soft strain gauge. [ABSTRACT FROM AUTHOR]

A Preisach-type vector hysteresis model is developed to represent anisotropic material characteristics under static and dynamic conditions. Bi- and uniaxial anisotropy are incorporated by generalizing the input projection of the vector model. Frequency-dependent eddy current and excess effects are considered by an additional field strength component. The model is applied to simulate the magnetic properties of weakly anisotropic nonoriented magnetic steel. The simulation results are successfully validated against measurements under alternating and circular flux carried out on a rotational single-sheet tester. [ABSTRACT FROM PUBLISHER]

Including highly conductive steel infrastructure into electromagnetic (EM) earth modeling is motivated by the fact that long metal-cased boreholes have the potential to be used as boosting antennas that enable larger source dipole moments and greater signal penetration depths. Unfortunately, geophysical algorithms designed to simulate EM responses over rather regional scales are complicated by material property contrasts and structure geometries that are more typical for EM engineering applications. Hence, the great majority of earth-modeling algorithms that consider EM responses from steel-cased boreholes use integral-equation methods. To be able to model complex casing scenarios, we revisited the finite-difference time-domain (FDTD) method to advance the modeling of transient-EM field responses from steel-cased boreholes. A time-dependent function that allows for larger FDTD time steps in the DuFort-Frankel method was developed, alleviating the generally large computational overhead. We compared our method against three different kinds of benchmark solutions to demonstrate the reliability of the FDTD field solutions. These test cases were canned out to check the feasibility of a final hydraulic fracturing study. Images of the electric current distribution in a sheetlike rock fracture were calculated for the cases with and without the presence of a connecting borehole casing, demonstrating the casing's potential of illuminating deep target zones. [ABSTRACT FROM AUTHOR]

Highlights: [•] Small quantities of copper were added to non-oriented electrical steels. [•] A metastable Cu-rich phase precipitated in hot-rolled bands. [•] The Cu-rich phase has a structure that differs from a twinned 9R or 3R. [•] The copper precipitates can improve the recrystallization textures of the steels. [•] The copper precipitates can also significantly reduce the core loss of the steels. [ABSTRACT FROM AUTHOR]

Abstract: The paper focuses on changes in mechanical and electrical properties of austenitic steel due to radiation swelling. Various micromechanical models for the electrical conductivity and elastic moduli are assessed based on the experimental data available in literature. We show that, in the considered case, the effective field method provides the best prediction for both elastic and conductive properties. Comparing the two sets of experimental data, the cross-property connections that relate changes in the elastic and electrical conductivity of a material due to radiation swelling has been verified. It is shown that analytical cross-property connection is in a good agreement with experimental data and can be used to estimate changes in electrical resistivity of a material from the changes in Young’s modulus or vice versa. [Copyright &y& Elsevier]

Mechanical properties of slab tracks on a foundation with nonlinear stiffness are accounted for. At first, the cracking stages were inspected in FEM models and it was learned that slab tracks have one-way exural behavior. Secondly, experimental full-scale models were made, and the accuracy of analyses was verified by comparing the FEM load-deflection curves with those of previous studies and validating the cracking and ultimate loads with those obtained from experiments. Finally, the effects of several parameters on the cracking and ultimate loads and the energy absorption of steel fiber-reinforced slab tracks were investigated by examining the real behavior of slab tracks on elastic foundations before and after cracking. Steel fibers increased the compressive and exural strengths as well as ductility and energy absorption. The 2.5 m width was the optimal width and the fracture pattern changed at this width. Finally, based on the obtained fracture loads, design curves were plotted for AASHTO's factored loads. [ABSTRACT FROM AUTHOR]

Abstract: Electrification occurs when metals are put into contact with polymers, and the mechanism is still not fully understood. In this paper, experimental study of contact electrification between a metal and polymers was conducted. Effects of contact cycle, load, and nominal area on electrification were investigated. Results showed that electrification charge increased with real contact area. However, experimental results showed that charge density increased with nominal area and decreased with load. The key factor that determined the charge density was contact stress. Charge density decreased with contact stress linearly. A quantitative relationship between charge density and contact stress was proposed. [Copyright &y& Elsevier]

Distributionsof potential and current and variations of crevice environments arestudied in a crevice under a simulated disbonded coating in soil extractsolutions (SES) with and without sulfate-reducing bacteria (SRB).Results show that forming of the crevice blocks the penetration ofcathodic currents in the crevice and weakens the cathodic polarizationof the steel Q 235. The cathodic currents in the presence of SRB arenearly three times more than those without SRB at the same cathodicprotective potential, which indicates that SRB increases the energyconsumption of the cathodic protection systems. SRB leads to basificationof the solution in the crevice. The forming of inner electric fieldenhances the anionic migration into the crevice. The forming of thereversed potential increases the cathodic current. [ABSTRACT FROM AUTHOR]

In order to eliminate errors that result from different properties of a calibration sample and a tested object when selecting the conditions for an eddy-current inspection, the electric and the magnetic properties of various steel grades were investigated that are necessary to analyze the positions of the hodographs on the flawless areas of the calibration sample and the test object and to make corrections for the expected changes in these properties that are caused by the effects of a gap for defective areas of a tested object. The study was carried out using samples that were manufactured of steel grades of different chemical compositions with a set of artificially made defects of known sizes. The test technique was evaluated on the basis of a reference specimen from D16 duralumin. The magnetic and electrical properties of the steel grades that are necessary to calculate the hodographs of the signals from the transition-type and lay-on eddy-current converters and to select test conditions are reported. [ABSTRACT FROM AUTHOR]

The physical and mechanical properties of 09Γ2C steel that was subjected to strengthening by intense plastic deformation using the method of equal channel angular pressing (ECAP) are studied. An unambiguous interrelationship between the magnetic (coercive force, maximal permeability, Barkhausen magnetic noise parameters) and mechanical (rupture limit, conditional yield strength, relative elongation and narrowing upon damaging) characteristics of 09Γ2C steel, which was strengthened using ECAP following different technological regimes, is demonstrated. Therefore, it is possible to estimate the strength and plasticity characteristics of the analyzed material based on the measurement of its magnetic parameters. It has been revealed that under conditions of uniaxial tension in the range from 0 to (0.2-0.6) of the conditional yield strength (depending on the ECAP regime), it is possible to diagnose changes in the stressed state of items that are made of 09Γ2C steel that is hardened in accordance with the ECAP technique using magnetic structuroscopy methods. [ABSTRACT FROM AUTHOR]

Abstract: Accurate measurement of electromagnetic properties of steels is of significant importance as electromagnetic properties are indicative of structure, performance and condition related parameters of the material. In this paper, we present the measurement of cylindrical power station steel samples with different degrees of degradation in their lifetime. Cylindrical air cored sensors were used. Analytical and numerical methods (Finite Elements Methods) were employed to calculate the sensor response of these samples. Experimental results were obtained for a range of samples and their electromagnetic properties inferred by fitting finite element models to the measured results. In addition, sensitivity and error analysis were carried out to evaluate the accuracy of the method. [Copyright &y& Elsevier]

Abstract: Aimed at the geometrical characteristics of the overall discrete of large cross-sectional aluminum-steel stranded conductor, combined with the composite properties of conductor material made of aluminum and steel, the mechanism characteristics of large cross-sectional aluminum-steel stranded conductor are studied in this paper from surface to inside, by the individual to the whole and by the same to the different. The principal stiffness, coupling stiffness and modulus of elasticity of aluminum-steel stranded conductor are analyzed and given by using the continuity and the same nature of strand and synthesizing tension,torsion,shear and bending etc factors. Simplified results and formulas for engineers also given in this paper. All kinds of stiffness are not only the need of the mechanical calculation of conducting wire and the design overhead transmission lines but also the contents which fill the gaps in china. Especially the optimized conclusion that the section stiffness of wire is asymmetric is innovative and the general conclusion is that the section stiffness is different with the change of cross-section location. Although optimization can eliminate their differences, but can not change the fact that the stiffness is asymmetry. The results of this paper also have practical value for various types of lifting wire rope and the current steel configuration. [Copyright &y& Elsevier]

Abstract: Although theoretical models have already been proposed, experimental data is still lacking to quantify the influence of grain size upon coercivity of electrical steels. Some authors consider a linear inverse proportionality, while others suggest a square root inverse proportionality. Results also differ with regard to the slope of the reciprocal of grain size–coercive field relation for a given material. This paper discusses two aspects of the problem: the maximum induction used for determining coercive force and the possible effect of lurking variables such as the grain size distribution breadth and crystallographic texture. Electrical steel sheets containing 0.7% Si, 0.3% Al and 24ppm C were cold-rolled and annealed in order to produce different grain sizes (ranging from 20 to 150μm). Coercive field was measured along the rolling direction and found to depend linearly on reciprocal of grain size with a slope of approximately 0.9(A/m)mm at 1.0T induction. A general relation for coercive field as a function of grain size and maximum induction was established, yielding an average absolute error below 4%. Through measurement of B 50 and image analysis of micrographs, the effects of crystallographic texture and grain size distribution breadth were qualitatively discussed. [Copyright &y& Elsevier]

The effects of flaws in the insulating coating of an electric anisotropic steel, which are formed during its laser processing in accordance with the optimal technology used in industry, on the elastic tensile stresses induced in the metal by the coating and magnetic properties were investigated. It was shown that discontinuity of insulating coating at the location of laser-beam action does not lead to a decrease in elastic tensile stresses and deterioration of magnetic properties of steel. [ABSTRACT FROM AUTHOR]

The resistance of sensitized 12Kh18N10T steel in aqueous electrolyte solutions, which model steaming condensates of the main refinery plants, namely, primary oil processing, reforming, and heavy fraction hydrorefining, is studied using chemical and electrochemical methods according to the Russian State Standard GOST 9.912. Condensate models were proposed based on many years of analyzing the steaming condensates of the Kirishi refinery plants. The main parameters of the steel susceptibility to pitting corrosion (pitting factor and electrochemical bases of pitting resistance) of the austenitic steels of Kh18N10T grade are shown to depend on the concentration of corrosive anions and their ratios in the solution. A system of correlation dependences is proposed for forecasting the probability of pit formation in the solutions. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this paper is to study the corrosion resistance and the insulating characteristics of an environment-friendly chromium-free coating on electrical steel. Design/methodology/approach - A water-based semi-inorganic environment-friendly insulating coating on electrical steel was developed. The coating system of silane coupling agent and rare earth salt were used first in this coating to replace the chromate containing coating. In this study, it provided a successful combination of coating and passivation. Findings - Several test results, such as insulating ability, corrosion resistance, adhesion strength and hardness, showed that the performance of the film complied fully with the industry standards, particularly excellent in its corrosion resistance and the maximum corrosion resistance (neutral salt-spray test) time up to 20?h. Originality/value - There have been few reports on the chromium-free insulating coating on electrical steel, and described in the paper, this environment-friendly insulating coating on electrical steel was found to be highly effective. [ABSTRACT FROM AUTHOR]

The present study investigates the relationship of process parameters in electro-discharge of CK45 steel with novel tool electrode material such as Al–Cu–Si–TiC composite produced using powder metallurgy (P/M) technique. The central composite second-order rotatable design had been utilized to plan the experiments, and response surface methodology (RSM) was employed for developing experimental models. Analysis on machining characteristics of electrical discharge machining (EDM) die sinking was made based on the developed models. In this study, titanium carbide percent (TiC%), peak current, dielectric flushing pressure, and pulse on-time are considered as input process parameters. The process performances such as material removal rate (MRR) and tool wear rate (TWR) were evaluated. Analysis of variance test had also been carried out to check the adequacy of the developed regression models. Al–Cu–Si–TiC P/M electrodes are found to be more sensitive to peak current and pulse on-time than conventional electrodes. The observed optimal process parameter settings based on composite desirability are TiC percent of 18%, peak current of 6 A, flushing pressure of 1.2 MPa, and pulse on-time of 182 μs for achieving maximum MRR and minimum TWR; finally, the results were experimentally verified. A good agreement is observed between the results based on the RSM model and the actual experimental observations. The error between experimental and predicted values at the optimal combination of parameter settings for MRR and TWR lie within 7.2% and 4.74%, respectively. [ABSTRACT FROM AUTHOR]

Abstract: In stress-controlled constant amplitude and service loading tests at ambient temperature mechanical stress-strain hysteresis, temperature and electrical resistance measurements were performed to characterize the fatigue behavior of the quenched and tempered steel SAE 4140. The applied measurement methods use deformation-induced changes of the microstructure in the bulk material and represent the actual fatigue state. A new test procedure combines any kind of load spectra with periodically inserted constant amplitude sequences to measure the plastic strain amplitude, the change in temperature and the change in electrical resistance at the same time. The average values of the measuring sequences are plotted as function of the number of cycles in cyclic ‘deformation’ curves and represent the summation of microstructural changes caused by service loading. On the basis of generalized Morrow and Basquin equations the physically based fatigue life calculation method “PHYBAL” was developed for constant amplitude and service loading. With only three fatigue tests, Woehler (S–N) and fatigue life curves can be calculated in very good agreement with experimental ones determined in a conventional manner. The application of “PHYBAL” provides an enormous saving of experimental time and costs. [Copyright &y& Elsevier]

Abstract: The passivation of 316L austenitic stainless steel in sulphuric acid solution has been measured at a single temperature, and then further, after a series of temperature sweeps. After 15h at 20°C and constant electrode potential, the passive current density has fallen to 16nAcm−2 and still continues to decline, with no evidence of an approach to the steady state. After subjecting the metal to a series of temperature sweeps the passive current density has decayed much further to ca. 0.5nAcm−2 and probably still decaying slowly. The metal is thereby rendered extremely passive. It is argued that the passive current density as measured by conventional potential sweep voltammetry is not in fact the steady state current density, because the true approach to a steady state is far too slow. [Copyright &y& Elsevier]

Magnetostriction in nonoriented (NO) electrical steels is a harmful source of vibration and acoustic noise in electrical machines. It is far more anisotropic than specific power loss, which results in more complexity in prediction of the vibration and acoustic noise. An investigation of the anisotropy in magnetostriction and mechanical elastic properties of a NO steel is presented in this paper. Measurements of deformation in the stator teeth of an induction motor model core were conducted in order to study the effect of the magnetostriction anisotropy. Strain due to Maxwell forces in the air gap was calculated and compared with the measured deformation. Measurement results indicate that anisotropic magnetostriction has a great impact on unsymmetrical deformation of the stator teeth of induction motor cores. [ABSTRACT FROM AUTHOR]

In this paper an attempt has been made to find optimal process parameters of abrasive mixed electrical discharge machining (AEDM). Taguchi methodology has been adopted for planning and analysing the experiments for optimising the multiple performance characteristics. The process input parameters, viz, concentration of silicon in dielectric fluid, current, pulse-on time, duty factor were chosen to study process performance in terms of material removal rate (MRR) and surface roughness (SR). The investigations result show that with addition of silicon abrasive powder (2 g 1-1) in kerosene dielectric fluid, material removal rate improves by 23% and surface roughness is reduced by 35 %. The optimum process conditions as suggested by the present study are verified by conducting confirmation experiments. [ABSTRACT FROM AUTHOR]

Abstract: Quantitative and qualitative analysis techniques were employed to study the first stages of ultra-high vacuum plasma nitriding of the 42CrMo4 steel. At constant treatment temperature, maintained for all samples at about 360°C, we have established the influence of treatment time on the chemical composition, thickness and electrical properties of the nitrided layer. In this purpose it was used a stacking atomic layer model describing the sample surface, which takes into account the attenuation depth of photoelectrons by the atomic monolayers. So, we have found that after 2h of nitriding in laboratory conditions, 70% of the nitrided layer was composed of iron oxide. Also, I–V measurements indicate an influence of the nitride overlayer with increasing treatment time. [Copyright &y& Elsevier]