Heat treatment of aluminum alloys is assessed by various quality-assurance methods that include metallographic examination, hardness measurements, mechanical property tests, corrosion-resistance tests, and electrical conductivity testing. The use of hardness measurements in the quality assurance of heat treated aluminum products is effectively used in conjunction with the measurement of surface electrical conductivity. This article provides a detailed discussion of the error sources in eddy-current conductivity measurements. It also presents useful information on the variation of electrical conductivity of alloy 2024 samples as a function of aging time at different isothermal holding temperatures.

The commonly used nondestructive testing of cast products include liquid penetrant inspection, radiographic inspection, fluoroscopic inspection and automated defect recognition, ultrasonic inspection, eddy current inspection, process-controlled resonant testing (PCRT), leak test, and electrical conductivity measurements. This article summarizes the application of these nondestructive tests to castings. It also tabulates a partial list of automotive part types and materials amenable to PCRT and lists the potential limitations to the use of PCRT.

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.

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.

Eddy-current inspection is based on the principles of electromagnetic induction and is used to identify or differentiate among a wide variety of physical, structural, and metallurgical conditions in electrically conductive ferromagnetic and nonferromagnetic metals and metal parts. This article discusses the advantages and limitations of eddy-current inspection, as well as the development of the eddy-current inspection process. It reviews the principal operating variables encountered in eddy-current inspection: coil impedance, electrical conductivity, magnetic permeability, lift-off and fill factors, edge effect, and skin effect. The article illustrates some of the principal impedance concepts that are fundamental to understanding of and effective application of eddy-current inspection. It discusses various types of eddy-current instruments, such as the resistor and single-coil system, bridge unbalance system, induction bridge system, and through transmission system. The article concludes with a discussion on the inspection of aircraft structural and engine components.

Nondestructive inspection (NDI) methods for cast iron are used to ensure that the parts supplied perform as required by the purchaser. This article focuses on the principal nondestructive methods used to inspect for anomalies in cast irons and to determine if the volume, shape, size, or number of these anomalies exceeds the maximum allowed by the purchaser. The nondestructive methods include visual inspection, dimensional inspection, liquid penetrant inspection, magnetic-particle inspection, eddy-current inspection, radiographic inspection, ultrasonic inspection, resonant testing, and leak testing. The technique, strengths, and weaknesses of each of the nondestructive methods are also discussed.

This article describes the fundamental aspects of three nondestructive evaluation (NDE) methods of solid-state welds in terms of operation principles. These methods are radiography, ultrasound, and eddy current methods. The article provides examples of these NDE techniques performed on various types of flaws resulting from solid-state welding processes.

A number of nondestructive evaluation (NDE) methods, such as radiography, ultrasound, and eddy current, are available to detect flaws in solid materials. This article describes the fundamental aspects of these NDE methods in terms of operation principles. It presents some examples of the methods performed on various types of flaws resulting from solid-state welding processes.

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.

This article discusses the installation of the most commonly used force-monitoring devices, namely, load cells and piezoelectric force sensors. It describes the purpose and operation of commonly used displacement sensors, such as linear variable differential transformers, proximity sensors, photoelectric sensors, and ultrasonic sensors. The article provides information on the sensors used for detecting tool breakages and flaws in parts, the measurement of material flow during sheet metal forming, and lubrication. It also describes the operating stages of machine vision systems used for automated quality-control purposes. The theory of eddy-current-based material properties evaluation is also discussed.

The potential for introducing defects during processing becomes greater as the relative density of pressed and sintered powder metallurgy (PM) parts increases and more multilevel parts with complex geometric shapes are produced. This article discusses the potential defects in pressed and sintered PM parts: density variations, compaction and ejection cracks, microlaminations, poor degree of sintering, and voids from prior lubricant agglomerates. It describes the various methods applicable to green compacts: direct-current resistivity testing, radiographic techniques, computed tomography, and gamma-ray density determination. The article also discusses the methods for automated nondestructive testing of pressed and sintered PM parts: acoustic methods-resonance testing, eddy current testing, magnetic bridge comparator testing, ultrasonic techniques, radiographic techniques, gamma-ray density determination, and visual inspection.

This article describes the applications, methods, and limitations of five principal nondestructive test methods, namely, penetrant testing, magnetic-particle testing, eddy current testing, radiographic testing, and ultrasonic testing. The article also provides guidance for the method selection for respective applications.

This article provides information on the application of nondestructive examination (NDE) technologies to tube and pipe products. These include modeling and simulation methods, eddy-current methods, magnetic methods, acoustic methods, and physical methods. A summary of nondestructive examination methods based on flaw type and product stage is presented in a table. The article also discusses in-service inspection of tubular products and presents an example that illustrates the importance of nondestructive testing (NDT) for welds in austenitic stainless steel tubing.

This article describes the test techniques that are available for monitoring crack initiation and crack growth and for obtaining information on fatigue damage in test specimens. These techniques include optical methods, the compliance method, electric potential measurement, and gel electrode imaging methods. The article discusses the magnetic techniques that are primarily used as inspection techniques for detecting fatigue cracks in structural components. It details the principles and operation procedures of the liquid penetrant methods, positron annihilation techniques, acoustic emission techniques, ultrasonic methods, eddy current techniques, infrared techniques, exoelectron methods, and gamma radiography. The article explains the microscopy methods used to determine fatigue crack initiation and propagation. These include electron microscopy, scanning tunneling microscopy, atomic force microscopy, and scanning acoustic microscopy. The article also reviews the X-ray diffraction technique used for determining the compositional changes, strain changes, and residual stress evaluation during the fatigue process.

Nondestructive testing (NDT), also known as nondestructive evaluation (NDE), includes various techniques to characterize materials without damage. This article focuses on the typical NDE techniques that may be considered when conducting a failure investigation. The article begins with discussion about the concept of the probability of detection (POD), on which the statistical reliability of crack detection is based. The coverage includes the various methods of surface inspection, including visual-examination tools, scanning technology in dimensional metrology, and the common methods of detecting surface discontinuities by magnetic-particle inspection, liquid penetrant inspection, and eddy-current testing. The major NDE methods for internal (volumetric) inspection in failure analysis also are described.

The success of a reliable non-destructive evaluation (NDE) application depends greatly on the expertise and thoroughness of the NDE engineering that is performed. This article discusses the general considerations of NDE in terms of NDE response and NDE system management and schedule. It describes the NDE engineering and NDE process control, along with some case studies related to the applications of NDE. The article reviews various models for predicting NDE reliability, such as ultrasonic inspection model, eddy current inspection model, and radiographic inspection model. It concludes with an example that illustrates the integration of an ultrasonic reliability model with a CAD system.

Superconductivity has been found in a wide range of materials, including pure metals, alloys, compounds, oxides, and organic materials. Providing information on the basic principles, this article discusses the theoretical background, types of superconductors, and critical parameters of superconductivity. It discusses the magnetic properties of selected superconductors and types of stabilization, including cryogenic stability, adiabatic stability, and dynamic stability. The article also focuses on alternating current losses in superconductors, including hysteresis loss, penetration loss, eddy current loss, and radio frequency loss. Furthermore, the article describes the flux pinning phenomenon and Josephson effects.

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 focuses on the basic turbulent flow, and the thermal, mass-transfer, and hydrodynamic phenomena for use in modeling physical processes during induction melting. It provides a discussion on transport phenomena equations that includes the approximation of convective terms in the transport equation and computational schemes for the fluid dynamics equation. The aspects of computational algorithms for specific magnetohydrodynamic problems with mutual influence of the magnetic field and melt flow due to the changing shape of the free surface are also considered. The article illustrates the application of the basic equations and approaches formulated for electromagnetic field and melt turbulent flow for the numerical study of an induction crucible furnace.

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.