Magnetic materials are broadly classified into two groups with either hard or soft magnetic characteristics. Soft magnetic behavior is essential in any application involving changing electromagnetic induction such as solenoids, relays, motors, generators, transformers, and magnetic shielding. This Article provides a description on ferromagnetic properties, the effect of impurities, alloying additions, heat treatment, residual stress, and grain size on magnetic properties. It also describes the alloy classification and magnetic testing methods of soft magnetic materials, which include high-purity iron, low-carbon steels, silicon steels, iron-aluminum alloys, nickel-iron alloys, iron-cobalt alloys, ferrites, and stainless steels. The Article discusses the corrosion resistance of soft magnetic materials, and provides information on selection of alloys for power generation applications, including motors, generators and transformers. It concludes with a short note on design and fabrication of magnetic cores.

Powder metallurgy (PM) techniques are effective in making magnetically soft components for use in magnetic part applications. This article provides an account of the factors affecting magnetism, permeability, and hysteresis losses. It includes information on the magnetic properties of PM materials that are used in the magnetic part applications, namely, pure iron, phosphorus irons, ferritic stainless steels, 50 nickel-50 iron, and silicon irons. The article describes the factors that affect and optimize magnetic properties. It contains a table that lists the magnetic properties possible in metal injection molding parts. The article also discusses ferromagnetic cores used in alternating current applications and some permanent magnets, such as rare earth-cobalt magnets and neodymium-iron-boron (neo) magnets.

This article presents an overview of the electric and magnetic parameters and discusses the significance of these parameters for electronic applications. It describes the components of analog and digital electronic circuits. The article discusses the augmenting technologies: magnetic and special technologies such as electrooptical. It provides information on the special applications of the electric and magnetic parameters.

Magnetic flux controllers are materials other than the copper coil that are used in induction systems to alter the flow of the magnetic field. This article describes the effects of magnetic flux controllers on common coil styles, namely, outer diameter coils, inner diameter coils, and linear coils. It provides information on the role of magnetic flux controllers for whole-body and local area mass-heating applications, continuous induction tube welding, seam-annealing inductors, and various induction melting systems, namely, channel-type, crucible-type, and cold crucible systems. The article also describes the benefits of the flux controllers for induction heat treating processes such as single-shot and scanning.

This article describes the fundamental theory of magnetic pulse welding (MPW). It reviews the equipment used for MPW, namely, work coil, capacitor bank, high-voltage power supply, high-voltage switches, and field shapers. The article discusses the MPW process and explains the critical parameters needed to obtain acceptable welds. Applications and safety guidelines of the MPW are also presented.

A major portion of microstructural analysis of magnetic materials has centered on examination of optical, electron, and scanning probe metallographic techniques. This article reviews the methods pertaining to the microstructural examination of bulk magnetic materials, including microscopy techniques specific to magnetic materials (e.g., domain imaging), with specific examples where possible. It includes metallographic sample preparation procedures, followed by descriptions of microstructures of bulk magnetic materials. Information on magnetically soft materials, permanent magnets, magnetism and magnetic domains is also included. Finally, the article discusses microscopy techniques unique to magnetic materials characterization. Techniques used in the study of magnetic domain structures (microstructure) include the magneto-optical Kerr method, the Faraday method, and the Bitter technique. Scanning electron microscopy (magnetic contrast Types I and II), scanning electron microscopy with polarization analysis, Lorentz transmission electron microscopy, and magnetic force microscopy are also examined.

Magnetic-particle inspection is a method of locating surface and subsurface discontinuities in ferromagnetic materials. This article discusses the applications and advantages and limitations of magnetic-particle inspection. It describes magnetic fields in terms of magnetized ring, magnetized bar, circular magnetization, longitudinal magnetization, and effects of flux direction. General applications, advantages, and limitations of the various magnetizing methods used in magnetic-particle inspection are listed in a table. The article discusses the items that must be considered in establishing a set of procedures for the magnetic-particle inspection of a specific part: type of current, type of magnetic particles, method of magnetization, direction of magnetization, magnitude of applied current, and equipment. It concludes with a discussion on demagnetization after magnetic-particle inspection.

Magnetic-particle inspection is a nondestructive testing technique used to locate surface and subsurface discontinuities in ferromagnetic materials. Beginning with an overview of the applications, advantages, and limitations of magnetic-particle inspection, this article provides a detailed account of the portable power sources available for magnetization, and the different ways of generating magnetic fields using yokes, coils, central conductors, prod contacts, direct-contact, and induced current. In addition, the article discusses the characteristics and classification, and properties of magnetic particles and suspended liquids. Finally, the article outlines the types of discontinuities (surface and subsurface) that can be identified by magnetic-particle inspection and the importance of demagnetization after inspection.

This article provides an overview of electromagnetic fields (EMFs) and discusses their direct and indirect effects on human health. It provides a detailed description of the exposure levels of EMFs in residential and work environments. The article examines the international and European standards and regulations regarding occupational exposure to EMFs encountered in industrial activities. It discusses the categories of work equipment or activities that may expose the worker above and under the orientation value. The article also describes the main principles underlying the protection system adopted for the frequency range of 50 Hz to 10 MHz.

After solidification and cooling, further processing and finishing of the castings are required. This article describes the general operations of shakeout, grinding, cleaning, and inspection of castings, with particular emphasis on automation technology. It illustrates the vertical core knockout machine and the A-frame core knockout machine and lists the advantages and disadvantages of the knockout machines. The article describes the general factors in automated or manual gate removal process. It concludes with discussion on the various types of inspection, such as liquid penetrant inspection, pressure testing, radiographic inspection, magnetic particle inspection, and ultrasonic inspection.

This article discusses the presses, auxiliary equipment, and dies used in the blanking and piercing of commonly used magnetically soft materials, namely, low-carbon electrical steels and oriented and nonoriented silicon electrical steels. It describes the effect of stock thickness and work metal composition and condition on blanking and piercing. The article provides an overview of the influence of burr height on stacking factors and presents a discussion on the lubrication and core plating of electrical steels that ease the process.

This article discusses the need of and the strain basis for residual stress measurements and describes the nature of residual stress fields. A generic destructive stress relief procedure is described along with the issues generally involved in each procedural step. The article presents the stress reconstruction equations to be used for computational reconstruction of the stress fields from the measured strains for the destructive methods. It provides information on the sectioning, material removal, strain measurement, and chemical methods of residual stress measurement. The article reviews the semidestructive methods of residual stress measurement: blind hole drilling and ring coring, spot annealing, and X-ray diffraction techniques. Nondestructive methods such as neutron diffraction, ultrasonic velocity, and magnetic Barkhausen noise techniques, are also discussed.

This article discusses the ferromagnetic properties of soft magnetic materials, explaining the effects of impurities, alloying elements, heat treatment, grain size, and grain orientation on soft magnetic materials. It describes the types of soft magnetic materials, which include high-purity iron, low-carbon irons, silicon (electrical) steels, nickel-iron alloys, iron-cobalt alloys, ferritic stainless steels, amorphous metals, and ferrites (ceramics). Finally, the article provides a short note on alloys for magnetic temperature compensation.

Electromagnetic problem solutions are based on the macroscopic theory of the continuous model for the electromagnetic field (EMF). It is described by a system of integral or partial differential equations for five vector quantities, namely, electric field strength, electric flux density, current density, magnetic field strength, and magnetic flux density. This article describes the behavior of the EMF by Maxwell's equations in integral or differential forms. It discusses the definition of potentials; methods of mathematical modeling; boundary conditions; and energy, power density, and electromagnetic forces.

The most popular metal hot working processes for which induction heating is applied are forging, forming, extrusion, and rolling. This article focuses on estimation techniques to determine basic induction heating process parameters, including coil power, length of heating line, and frequency selection. It discusses three modes of heat transfer: conduction, convection, and radiation, in induction heating. The article describes the factors affected by a distortion of the magnetic field at the coil end through a schematic illustration of distribution of three magnetic force components experienced by the turns of the coil. It concludes with information on some case studies of numerical simulation.

This article discusses the principles and limitations of micromagnetic techniques, namely, magnetic Barkhausen noise (MBN) and magnetoacoustic emission (MAE). It also discusses various factors limiting the establishment of acceptance criteria for test components as they pertain to the successful application of MBN measurement and signal interpretation. The article provides an overview of basic magnetic phenomena and dynamics in ferromagnetic materials that underlie the origin of MBN emissions. It describes the changes in the domain structure of the ferromagnetic material under an applied external field. The relationship between uniaxial stress and angular-dependent strain is also discussed. The influence of stress on domain walls, and therefore, the generation of Barkhausen noise are described. The article also describes the directional and angular MBN measurements and provides information on detection, angular dependence, and advanced analysis methods of MBN emissions.

Ceramic materials serve important insulative, capacitive, conductive, resistive, sensor, electrooptic, and magnetic functions in a wide variety of electrical and electronic circuitry. This article focuses on various applications of advanced ceramics in both electric power and electronics industry, namely, dielectric, piezoelectric, ferroelectric, sensing, magnetic and superconducting devices.

Hyperthermia is a type of cancer treatment that requires directing a carefully controlled dose of heated nanoparticles to the cancerous tumor that leads to the destruction of cancer cells. Nanoparticles are used as the heat generating sources within the cancer cells and the tumors. The problem in controlling the temperature of nanoparticles is solved by the use of induction heating, which uses a high-frequency alternating magnetic field localized in the area of interest. This article provides an overview of this technique along with the description of its major components, namely, nanoparticles, induction heating setup, and magnetic field strength.

In an induction heating system, thermal and electromagnetic properties of heated materials make the greatest impact on the heat transfer and performance of induction heating process. This article focuses on major thermal properties, namely, thermal conductivity, heat capacity, and specific heat. It describes the two important electromagnetic properties, electrical resistivity (electrical conductivity) and magnetic permeability, which posses the most pronounced effect on the performance of the induction heating system, its efficiency, and selection of main design parameters. The article also discusses the magnetic properties of diamagnetic, paramagnetic, ferromagnetic, ferrimagnetic, antiferromagnetic, and metamagnetic materials.

This article focuses on nondestructive inspection of steel bars. The primary objective in the nondestructive inspection of steel bars and wire is to detect conditions in the material that may be detrimental to the satisfactory end use of the product. The article discusses various types of flaws encountered in the inspection of steel bars, including porosity, inclusions, scabs, cracks, seams, and laps. Inspection methods, such as magnetic-particle inspection. liquid penetrant inspection, ultrasonic inspection, and electromagnetic inspection, of steel bars are also described. The article provides a discussion on electromagnetic systems, eddy-current systems, and magnetic permeability systems for detection of flaws on steel bars. It concludes with a description of nondestructive inspection of steel billets.