This article reviews the steps involved in presurface-preparation inspection: substrate replacement; removal of weld spatter, rounding of sharp edges, and grinding of slivers/laminations; and removal of rust scale, grease, oil, and chemical (soluble salt) contamination. It focuses on surface preparation methods that range from simple solvent cleaning to hand and power tool cleaning, dry and wet abrasive blast cleaning, centrifugal wheel blast cleaning, chemical stripping, and waterjetting for the application of the coating system. In addition, the article provides a description of the Society for Protective Coatings' (SSPC) standards and NACE International standards as well as the International Organization for Standardization (ISO) standards and International Concrete Repair Institute (ICRI) guidelines for surface cleanliness.

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.

X-ray powder diffraction (XRPD) techniques are used to characterize samples in the form of loose powders, aggregates of finely divided material or polycrystalline specimens. This article provides a detailed account of XRPD. It begins with a discussion on XRPD instrumentation and the techniques used to characterize samples. The article then describes the principles, advantages, and disadvantages of various types of powder diffractometers. A section on the Rietveld method of diffraction analysis is then presented. The article discusses various methods and procedures for qualifying and quantifying phase mixtures in powder samples. It provides information on typical sensitivity and experimental limits on precision of XRPD analysis and other systematic sources of errors that affect accuracy. Some of the factors pertinent to the estimation of crystallite size and defects are also presented. The article ends with a few application examples of XRPD.

This article summarizes the terminology for gas reactions, and discusses low-temperature nitriding and nitrocarburizing of stainless steels. It describes the various nitriding processes, namely, high- and low-pressure nitriding, oxynitriding, sulfonitriding, oxysulfonitriding, ferritic nitrocarburizing and austenitic nitrocarburizing. The article includes a discussion on the difficulties in specimen cleaning, importance of furnace purge, uses of pre and post oxidation, depassivation, or activation, and requirements for perfect nucleation in nitriding process. In nitriding, the successful atmosphere control depends on various potentials. The article summarizes the methods of measuring potentials in nitriding and nitrocarburizing, provides useful information on the furnaces used, and the safety precautions to be followed in the nitriding process. It also describes the sample preparation procedures and testing methods to ensure the quality of the sample.

This article presents the three levels of investigations of distortion engineering. On Level 1, the parameters and variables influencing distortion in every manufacturing step must be identified. More than 200 parameters can affect distortion. The design of experiments approach allows for the investigation of larger numbers of parameters by a limited number of samples, and can be structured into system analysis, test strategy, test procedure, and test evaluation. Level 2 focuses on understanding the distortion mechanisms by using the concept of distortion potential and its carriers. Distortion engineering aims to compensate distortion using the so-called compensation potential (Level 3). Level 3 discusses the measures to improve homogeneity, and respectively the symmetry, of the carriers of the distortion potential. The article also discusses the compensation of the resulting size and shape changes of the existing asymmetries by well-directed insertions of additional inhomogeneity/asymmetries in one or more of the distributions of the carriers.

This article reviews many commonly used stereological counting measurements and the relationships based on these parameters. The discussion covers the processes involved in sampling and specimen preparation. Quantitative microstructural measurements are described including volume fraction, number per unit area, intersections and intercepts per unit length, grain size, and inclusion content.

Examination of a damaged component involves a chain of activities that, first and foremost, requires good observation and documentation. Following receipt and documentation, the features of damage can be recorded and their cause(s) investigated, as this article briefly describes, for typical types of damage experienced for metallic components. This article discusses the processes involved in visual or macroscopic examination of damaged material; the interpretation of fracture features, corrosion, and wear damage features; and the analysis of base material composition. It covers the processes involved in the selection of metallurgical samples, the preparation and examination of metallographic specimens in failure analysis, and the analysis and interpretation of microstructures. Examination and evaluation of polymers and ceramic materials in failure analysis are also briefly discussed.

X-ray diffraction (XRD) residual-stress analysis is an essential tool for failure analysis. This article focuses primarily on what the analyst should know about applying XRD residual-stress measurement techniques to failure analysis. Discussions are extended to the description of ways in which XRD can be applied to the characterization of residual stresses in a component or assembly and to the subsequent evaluation of corrective actions that alter the residual-stress state of a component for the purposes of preventing, minimizing, or eradicating the contribution of residual stress to premature failures. The article presents a practical approach to sample selection and specimen preparation, measurement location selection, and measurement depth selection; measurement validation is outlined as well. A number of case studies and examples are cited. The article also briefly summarizes the theory of XRD analysis and describes advances in equipment capability.

The process of coating plastics with metals for functional purposes is called metallizing of plastics. This article discusses the metallizing of plastics, provides information on its history, and gives a short note on applications and adhesion properties of metallic coatings. It also discusses the selection of plastics for plating. This article also describes metallizing techniques, including plating (electrolytic or electroplating), vacuum metallizing and thermal spraying, and environmental considerations. The article discusses the quality assurance procedures for metallized plastic parts which include tests that assess the quality of the finish, coating thickness, adhesion, and corrosion resistance, and gives a short note on service performance, which includes service condition classifications.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of precipitation-hardening stainless steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the cup-and-cone tension-overload fracture, low-cycle and high-cycle fatigue fracture, fracture surface, brittle intergranular fracture, hydrogen embrittlement, and intergranular stress-corrosion cracking of stainless steel components of these steels. The components include high-pressure compressor parts, springs, deflector yokes of aircraft main landing gears, and aircraft engine mount beams.

Case depth is the normal distance from the surface of the steel to the start of the core. Measurement of case depth is highly sensitive to the type of case hardening, original steel composition, quenching condition, and even to the testing method. This article describes the various methods of measuring case depth in steels, including chemical methods such as the combustion analysis and spectrographic analysis, microhardness test method, macroscopic and microscopic visual methods, and nondestructive methods. It contains a table that provides approximate equivalent hardness numbers for steel.

Metallographic examination is one of the most important procedures used by metallurgists in failure analysis. Typically, the light microscope (LM) is used to assess the nature of the material microstructure and its influence on the failure mechanism. Microstructural examination can be performed with the scanning electron microscope (SEM) over the same magnification range as the LM, but examination with the latter is more efficient. This article describes the major operations in the preparation of metallographic specimens, namely sectioning, mounting, grinding, polishing, and etching. The influence of microstructures on the failure of a material is discussed and examples of such work are given to illustrate the value of light microscopy. In addition, information on heat-treatment-related failures, fabrication-/machining-related failures, and service failures is provided, with examples created using light microscopy.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of austenitic stainless steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the following: fatigue-crack fracture, rock candy fracture, cleavage fracture, brittle fracture, high-cycle fatigue fracture, fatigue striations, hydrogen-embrittlement failure, creep crack propagation, fatigue crack nucleation, intergranular creep fracture, torsional overload fracture, stress-corrosion cracking, and grain-boundary damage of these steels. The austenitic stainless steel components include spring wires, preheater-reactor slurry transfer lines and gas lines of coal-liquefaction pilot plants, oil feed tubes and suction couch rolls of paper machines, cortical screws and compression hip screws of orthopedic implants, and Jewett nails.

This article focuses on characterizing the fracture-surface appearance at the microscale and contains some discussion on both crack nucleation and propagation mechanisms that cause the fracture appearance. It begins with a discussion on microscale models and mechanisms for deformation and fracture. Next, the mechanisms of void nucleation and void coalescence are briefly described. Macroscale and microscale appearances of ductile and brittle fracture are then discussed for various specimen geometries (smooth cylindrical and prismatic) and loading conditions (e.g., tension compression, bending, torsion). Finally, the factors influencing the appearance of a fracture surface and various imperfections or stress raisers are described, followed by a root-cause failure analysis case history to illustrate some of these fractography concepts.

Control of grain flow is one of the major advantages of shaping metal parts by rolling, forging, or extrusion. This article shows the effects of anisotropy on mechanical properties. Cylindrical forgings commonly have a straight parting line located in a diametral plane. The alternate classes of parting lines are called either "straight" or "broken" for brevity. Regardless of whether draft is applied or natural, the forging will have its maximum spread or girth at the parting line. Proper placement of the parting line ensures that the principal grain flow direction within the forging will be parallel to the principal direction of service loading. The article reviews the mutual dependence of parting line and forging process. It provides a checklist for the forging designer that suggests a systematic approach for establishing parting line location. Finally, the article contains examples, with illustrations of parting line locations, accompanied by tables of design parameters.

This article describes the methods and equipments involved in the preparation of specimens for examination by light optical microscopy, scanning electron microscopy, electron microprobe analysis for microindentation hardness testing, and for quantification of microstructural parameters, either manually or by the use of image analyzers. Preparation of metallographic specimens generally requires five major operations: sectioning, mounting, grinding, chemical polishing, and etching. The article provides information on the principles of technique selection in mechanical polishing, and describes the procedures, advantages, and disadvantages of electrolytic and chemical polishing. It also provides a detailed account of procedures, precautions, and composition for preparation and handling of etchants.

This article focuses on the effects of mechanical plasticity on workability; that is, process control of localized stress and strain conditions to enhance workability. It describes the nature of local stress and strain states in bulk forming processes, leading to a classification scheme, including testing procedures and specific process measurements, that facilitate the application of workability concepts. Using examples, the article applies these concepts to forging, rolling, and extrusion processes. The stress and strain environments described in the article suggest that a workability test should be capable of subjecting the material to a variety of surface strain combinations. By providing insights on fracture criteria, these tests can be used as tools for troubleshooting fracture problems in existing processes, as well as in the process development for new product designs.

Quantifying microstructural parameters has received considerable attention and success in developing procedures and using such data to develop structure/property relationships has been achieved. This article reviews many of the simple stereological counting measurements of volume fraction, grain structure (two-phase grain structures, and nonequiaxed grain structures), grain size, and inclusion content. It also reviews simple relationships between number of grains per unit area, number of intersections of a line of known length with particle or grain, and number of interceptions of particles or grains by a line of known length.