Time-of-flight diffraction (TOFD) is an ultrasonic technique used to detect diffracted waves from crack tips and to size the cracks from the arrival times of those waves. This article discusses the basic considerations and provides information on probe selection, gain setting, and instrumentation of TOFD. It describes the numerous effects that result from modifying the probe characteristics. The article provides the American Society of Mechanical Engineers (ASME), the European Committee for Standardization (CEN), and the International Standardization Organization (ISO) recommendations for the reference blocks according to applicable codes and standards. It also provides the ASME, CEN, and ISO recommendations for examination of welds. The article concludes with information on the interpretation and analysis of TOFD images with an aid of sizing algorithms.

Computed tomography (CT) is an imaging technique that generates a three-dimensional (3-D) volumetric image of a test piece. This article illustrates the basic principles of CT and provides information on the types, applications, and capabilities of CT systems. A comparison of performance characteristics for film radiography, real-time radiography, and X-ray computed tomography is presented in a table. A functional block diagram of a typical computed tomography system is provided. The article discusses CT scanning geometry that is used to acquire the necessary transmission data. It also provides information on digital radiography, image processing and analysis, dual-energy imaging, and partial angle imaging, of a CT system.

This article identifies the coatings applied to many substrates for both beautification and protection, and the inherent conflicts that exist between the coatings and the buildings they are designed to protect; emphasis is placed on masonry walls. It provides information on the purposes of the coatings in the commercial buildings. The article briefly describes some of the most common types of substrates found in buildings and the coatings commonly associated with each substrate. The selection of the coating system depends on the substrate and service expectations. The article addresses the primary causes of masonry coating problems and also provides a detailed discussion on the wall design considerations, moisture considerations, and coating system challenges in the masonry buildings.

Film radiography requires the development of the exposed film so that the latent image becomes visible for viewing. It describes the general characteristics of film, including speed, gradient, and graininess, and the factors affecting film selection and exposure time. The article discusses the three major inspection techniques for tubular sections, namely, the double-wall, double-image technique; the double-wall, single-image technique; and the single-wall, single-image technique. It illustrates the arrangements of penetrameters and identification markers for the radiography of plates, cylinders, and flanges. The article discusses various control methods, including the use of lead screens; protection against backscatter and scatter from external objects; and the use of masks, diaphragms, collimators, and filtration. The radiographic appearance of specific types of flaws is also discussed. The article concludes with a discussion on two methods of radiographic film processing: manual and automatic processing.

This article provides an overview of the corrosion theory relating to refractories on the basis of acid/base reactions, thermodynamics, and kinetic considerations. The tests to evaluate refractory corrosive wear are reviewed. The article describes the specific refractories used in steel, glass, aluminum, and chemical-resistant applications. Specific material issues that should be considered or evaluated when choosing or using refractory materials are discussed.

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 focuses on the application of solid-state nuclear magnetic resonance (NMR) spectroscopy in materials science, especially for inorganic and organic polymer solids. It begins with a discussion on the general principles of NMR, providing information on nuclear spin descriptions and line narrowing and spectral resolution and describing the impact of magnetic field on nuclear spins and the factors determining resonance frequency. This is followed by a description of various systems and equipment necessary for NMR spectroscopy. A discussion on general sampling for solid-state NMR, sample-spinning requirements, and extraneous signals is then included. Various factors pertinent to accurate calibration of the NMR spectrum are also described. The article provides information on some of the parameters both beneficial and problematic for processing NMR data. It ends with a description of the applications of NMR in glass science and ceramics.

Self-consistent models are a particular class of models in continuum micromechanics, that is, the field concerned with making predictions of the properties and evolution of aggregates whose single-crystal deformation behavior is known. This article provides information on the measurement and representation of textures as well as prediction of texture evolution in single-phase materials and two-phase aggregates.

Coining is a closed-die forging operation in which all surfaces of the workpiece are confined or restrained, resulting in a well-defined imprint of the die on the workpiece. This article focuses on the coining equipment (hammers and presses), lubricants, and general and special die materials used in the coining process. It discusses the coinability of metals such as steels, copper, and composite metals. The article describes the control of dimensions, surface finishes, and weight of coined items. It concludes with a discussion on processing problems and solutions.

This article begins with an overview of classes and applications of gray iron. It discusses the castability of gray iron in terms of section sensitivity and fluidity. The article provides information on the dimensions of prevailing sections recommended for gray irons and reviews the properties and specifications of test bar. It discusses the properties of gray iron, such as fatigue limit, pressure tightness, impact resistance, machinability, and dimensional stability, at both room and elevated temperature. Wear behavior of gray iron castings during sliding contact under conditions of normal lubrication is also discussed. The article reviews the use of alloys and heat treatment to modify as-cast properties. It concludes with information on physical properties of gray iron castings.

Electrodeposition of tin alloys is used to protect steel against corrosion or wear, to impart resistance to etching, and to facilitate soldering. This article focuses on the compositions, operating conditions, advantages, and limitations of methane sulfonic acid plating solutions and fluoborate plating solutions for tin-lead. It briefly describes the solution compositions and operating conditions of tin-bismuth, tin-nickel, and tin-zinc.

Both nondestructive testing (NDT) and nondestructive evaluation (NDE) use noninvasive measurement techniques to gain information about defects and various properties of materials, components, and structures. This article begins with a discussion on the historical development of quantitative measurement techniques, evaluation reliability, and quantitative interpretation of nondestructive inspection methods. The common nondestructive evaluation methods, along with their uses and limitations, are summarized in a table. The article conceptually illustrates the interplay of NDE and fracture mechanics in the damage tolerant approach. It concludes with information on pressure vessel applications that can be separated into three protocols used by military nuclear power, commercial nuclear power, and non-nuclear pressure vessels and/or fired boilers.

In the handling of molten aluminum, it is fairly common to use filters as a part of the melting unit and in the gating and/or riser system. This article describes the methods of in-furnace and in-mold filtration, with emphasis on the filtration of molten aluminum. It discusses the factors that influence the formation of inclusions. The article describes the three basic methods of mechanically removing or separating inclusions from molten metal. The methods include sedimentation, flotation, and positive filtration. The article provides a discussion on the types of molten-metal filters, including bonded-particle filters, cartridge filters, and ceramic foam filters. It lists the factors that are important in achieving optimum performance of any in-furnace filtering application. The article concludes with information on filtered metal quality.

This article focuses on the construction, operation of electric arc furnaces (EAF), and their auxiliary equipment in the steel foundry industry. It provides information on the power supply of EAF and discusses the components of the EAF, including the roof, furnace shell, spout and tap hole, water-cooling system, preheat and furnace scrap burners, and ladles. The article describes the acid and basic steelmaking practices. It discusses the raw materials used, oxidation process, methods of heat reduction, and deoxidation process in the practices. The article provides a discussion on arc melting of iron and EAF steelmaking.

This article describes the casting characteristics and practices of copper and copper alloys. It discusses the melting and melt control of copper alloys, including various melt treatments to improve melt quality. These melt treatments include fluxing and metal refining, degassing, deoxidation, grain refining, and filtration. The article provides a discussion on these melt treatments for group I to III alloys. It describes the three categories of furnaces for melting copper casting alloys: crucible furnaces, open-flame furnaces, and induction furnaces. The article explains the important factors that influence the selection of a casting method. It also describes the production of copper alloy castings. The article concludes with a discussion on the gating and feeding systems used in production of copper alloy castings.

This article provides an overview of the thixocasting process and discusses the concepts that are important to the practical application of this technology. The thixocasting process involves two casting processes. The first casting process is required to make the feedstock that must be reheated to achieve the structures necessary for casting. The second casting process combines billet sawing, reheating, and the actual injecting of material into the mold. The article focuses on these processes and provides information on rheological tests. It discusses some key design concepts used in thixocasting. The article illustrates the differences between a conventional high-pressure die-casting injection profile and the thixocasting injection profile used to produce the same part.

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 is a pictorial guide to forms of corrosion that draws attention to common pitfalls or situations that have caused premature corrosion, sometimes with expensive consequences. The examples used are not exhaustive; they highlight the necessity to fully examine materials, conditions, and specific circumstances that together can reduce the anticipated service life of a component or plant. The color images in this article are categorized according to the type of corrosion following the general order that is adopted in Volume 13A of ASM Handbook. The first table of the article provides a categorization of the forms of corrosion. It also provides a reference to articles or sections of articles in Volume 13A that detail the particular corrosion form or mechanism. The second table is a guide listing the figures in this article by material and by the corrosion form or mechanism illustrated.

This article describes the four basic steps of the purchasing process of cast components. The steps include defining requirements and developing a purchasing plan; requesting and evaluating bids from potential sources; selecting a source and negotiating contract terms; and carrying out the contract and pursuing continuous improvement. It provides guidance on purchasing cast components and describes specific issues and approaches that have proved useful in purchasing castings. The article presents a list of the most significant considerations when attempting to determine the overall cost and design requirements of a metal casting.