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.

This article describes the applications of induction heat treatment of metals, including normalizing, annealing, hardening, and tempering and stress relieving. It discusses the simulation techniques of the electromagnetic and thermal processes that occur during induction heat treating. The article explains the finite-difference method, finite-element method, mutual impedance method, and boundary-element method for the numerical computation of the induction heat treating processes. It also discusses the direct and indirect coupling approaches for coupling the electromagnetic and heat-transfer problems. Modern computer simulation techniques are capable of effectively simulating electromagnetic and thermal phenomena for many processes that involve electromagnetic induction. The article considers the challenges faced by developers of modern simulation software.

This article focuses on the methods that are being developed for detecting and monitoring corrosion: electrochemical methods, electromagnetic or sound wave methods, fiber-optic technology, fluorescence methods, and the Diffracto Sight method. It reviews the importance of data management and the Corrosion Expert System. It concludes with information on the simulation and modeling for incorporating the mechanisms of corrosion prevention into military hardware systems design and operation.

This article emphasizes the traits that are common to high-velocity forming operations. It describes general principles on how metal forming is accomplished and analyzed when inertial forces are large. The article discusses the principal methods of high-velocity forming, such as explosive forming, electrohydraulic forming, and electromagnetic forming. It provides examples that illustrate how these methods can be practically applied. The article concludes with information on the status and development potential for the technology.

Inspection involves two types of testing, namely, destructive and non-destructive. This article provides an overview of the various inspection plans, such as first-article inspection and periodic tests done by destructive metallurgical testing and the final inspection done by the application of non-destructive technology. It describes the processes involved in destructive methods, such as surface hardness measurement, induction hardening pattern and heat-affected zone inspection, and the examination of microstructure before and after induction hardening. It also discusses non-destructive evaluation techniques for defect detection and microstructure characterization as well as non-destructive evaluation for real-time monitoring of induction process.

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.

In terms of their electrical properties, plastics can be divided into thermosetting and thermoplastic materials, some of which are conductive or semiconductive. This article provides detailed information on factors that affect the property of plastics. It discusses the major test methods used to determine the following dielectric properties of plastics: dielectric breakdown voltage, dielectric strength, dielectric constant, dissipation factor, arc tracking resistance, insulation resistance, volume, and surface resistivity or conductivity. The test specifications and conditions, recommended by several U.S. and foreign testing organizations for characterizing the electrical properties of plastic materials are listed. The article describes the influence of these properties on selection of plastics for insulation application. An outline of the electromagnetic shielding and testing methods of electromagnetic interference are also provided. Designations, electrical properties, and applications of elastomers are tabulated.

Designing of induction heating, or, generally electro technological installations, requires mathematical modeling for solving problems related to various physical phenomena, including electromagnetic (EM), thermal, mechanical, fluidic, and metallurgical fields. This article focuses on the solution of Maxwell's equations (MEs) and provides some basic information regarding the heat transfer and fluid equations, because these physical phenomena usually are strongly coupled to magnetic and electric fields. The solutions are usually obtained by using specific numerical methods such as finite-element method, finite difference method, boundary-element method or volume-integral method, and direct-solution method. The article also discusses the typical structure of commercial codes (preprocessor, solver, and postprocessor) to solve field problems mainly in finite-element method.

Eddy-current inspection is a nondestructive evaluation method based on the principles of electromagnetic induction. Eddy-current methods are used to identify or differentiate a wide variety of physical, structural, and metallurgical conditions in electrically conductive ferromagnetic and nonferromagnetic metals and metal parts. Giving a brief introduction on the uses of eddy-current inspection, this article discusses the operating principles and the principal operating variables encountered in eddy-current inspection, including coil impedance, electrical conductivity, magnetic permeability, lift-off and fill factors, edge effect, and skin effect. It further describes different aspects of eddy current testing such as the selection of inspection frequencies and the types and configurations of inspection coils. The article also deals with the eddy current instrumentation and the discontinuities that are detectable by eddy-current methods.

Polymeric materials that possess similar solubility parameters can be joined using a variety of polymer joining techniques. This article describes commonly available fusion-welding techniques such as joining methods, key joining parameters, and the application areas of each joining method. The techniques are hot-tool, hot-gas, extrusion, focused infrared, laser, friction, vibration, spin, ultrasonic, and electromagnetic welding techniques (resistance, induction, dielectric, and microwave welding). The article concludes with a discussion on welding evaluation methods.

This article presents the different hardness test methods used to measure the effectiveness of surface carbon control in carburized parts of steel. Common test methods include Rockwell hardness measurements, superficial Rockwell 15N testing, and microhardness testing. The article provides information on the microscopic method used to detect smaller variations in carbon content, and reviews consecutive cuts analysis and spectrographic analysis that are used to accurately evaluate the carbon concentration profile of carburized parts. It describes procedures of and precautions to be undertaken during shim stock analysis, which is used to measure the atmosphere carbon potential. The article includes a discussion on the electromagnetic nondestructive tests that are used to evaluate the case depth of case-hardened parts.

Induction heating computations deal with a multiphysics problem containing analysis of several coupled physical fields such as electromagnetic, temperature, mechanical, and metallurgical. In order to solve coupled electromagnetic-temperature field problems, it is necessary to develop suitable algorithms and numerical procedures, which make it possible to deal with these nonlinear coupled problems. This article focuses on the most common approaches to coupled electromagnetic and heat transfer problems, namely, weak-, quasi-, and hard-coupled formulations.

Induction hardening of steel components is the most common application of induction heat treatment of steel. This article provides a detailed account of electromagnetic and thermal aspects of metallurgy of induction hardening of steels. It describes induction hardening techniques, namely, scan hardening, progressive hardening, single-shot hardening, and static hardening. The article discusses the techniques used to control the heat pattern, and provides a brief review of quenching techniques used in the induction hardening. It provides guidelines for selecting the frequency and power for induction hardening, and describes common methods for measuring case depth, such as optical and microhardness, and surface hardness. It provides information on some complications and ambiguities associated with these measurements. The article also discusses the commonly used non-destructive testing methods, namely, magnetic particle testing, ultrasonic testing, and eddy current testing to evaluate induction-hardened components.

This article introduces the principal methodologies and some advanced technologies that are being applied for nondestructive evaluation (NDE) of fiber-reinforced polymer-matrix composites. These include acoustic emission, ultrasonic, eddy-current, computed tomography, electromagnetic acoustic transducer, radiography, thermography, and low-frequency vibration methods. The article also provides information on NDE methods commonly used for metal-matrix composites.

This article provides an overview of the characteristics of Rayleigh waves plus methods for generation and detection of waves, including using piezoelectric transducers or noncontact techniques such as lasers, electromagnetic acoustic transducers, or air-coupled ultrasonics. It reviews the methods for using Rayleigh waves for defect detection and materials characterization, alongside nonlinear ultrasonic inspection and surface acoustic wave (SAW) microscopy. The article concludes with information on the standards that use Rayleigh waves for nondestructive evaluation (NDE) of different structures.

Electron spin resonance (ESR), or electron paramagnetic resonance (EPR), is an analytical technique that can extract a great deal of information from any material containing unpaired electrons. This article explains how ESR works and where it applies in materials characterization. It describes a typical ESR spectrometer and explains how to tune it to optimize critical electromagnetic interactions in the test sample. It also identifies compounds and elements most suited for ESR analysis and explains how to extract supplementary information from test samples based on the time it takes electrons to return to equilibrium from their resonant state. Two of the most common methods for measuring this relaxation time are presented as are several application examples.

Microwaves (or radar waves) are a form of electromagnetic radiation with wavelengths between 1000 cm and 1 mm in free space. One of the first important uses of microwaves in nondestructive evaluation was for components such as waveguides, attenuators, cavities, antennas, and antenna covers (radomes). This article focuses on the microwave inspection methods that were subsequently developed for evaluation of moisture content in dielectric materials; thickness measurements of thin metallic coatings on dielectric substrates; and detection of voids, delaminations, macroporosity, inclusions, and other flaws in plastic or ceramic materials. It also discusses the advantages and disadvantages and the general approaches that have been used in the development of microwave nondestructive inspection.

Electroless, or autocatalytic, metal plating is a nonelectrolytic method of deposition from solution that can be plated uniformly over all surfaces, regardless of size and shape. The plating's ability to plate onto nonconductors is an advantage that contributes to the choice of electroless copper in various applications. This article provides information on the bath chemistry and deposit properties of electroless copper and discusses the applications of electroless copper plating, such as printed wiring boards, decorative plating-on-plastic, electromagnetic interference shielding, and hybrid and other advanced applications. It describes two commercial processes, pretreatment and post-treatment. The article reviews the solutions used, controls and control equipment, and performance criteria of electroless copper plating. It concludes with information on the environmental and safety issues associated with electroless copper plating.

This article presents the basic guidelines considered in designing a composite structure, and the basic definitions of terms that apply to composites. It describes the analysis of a composite laminate based on stress-strain relationships, stress-strain load relationships, general load displacement case, and general load case solution. Factors affecting the composite materials properties and allowables of fiber-reinforced polymers are reviewed. The article discusses the process considerations for mold design, such as master model, metal tooling, composite tooling, and tool care. It explains the resin selection in designing the composite for use in a particular application. The article illustrates the various methods that are used to process a composite component, namely, wet lay-up, autoclave, resin transfer molding, and vacuum-assisted resin transfer molding. It provides a discussion on electromagnetic interference shielding, electrostatic discharge protection, metal plating, fire resistance, and corrosion resistance on composite materials.