This article reviews nondestructive and destructive test methods used to characterize welds. The first process of characterization discussed involves information that may be obtained by direct visual inspection and measurement of the weld. An overview of nondestructive evaluation is included that encompasses techniques used to characterize the locations and structure of internal and surface defects, including radiography, ultrasonic testing, and liquid penetrant inspection. The next group of characterization procedures discussed is destructive tests, requiring the removal of specimens from the weld. The third component of weld characterization is the measurement of mechanical and corrosion properties. Following the discussion on the characterization procedures, the second part of this article provides examples of how two particular welds were characterized according to these procedures.

This chapter discusses the engineering significance of steel and briefly describes its chemical composition, crystal structure, Fe-C phases, and associated characterization techniques.

Visual inspection is the most important method of inspection of materials. This chapter describes the procedures involved in visual inspection such as identification markings, identification of defects caused by heating problems, scaling of materials, cracking characterization, and measurement of material dimensions. It discusses the mechanisms, advantages, limitations, components, and applications of various visual inspection tools, namely magnifying devices, lighting for visual inspection, measuring devices, miscellaneous measuring equipment, record-keeping devices, and macroetching.

This chapter discusses the practices and procedures used to reveal and record macrostructural features such as hardening depth, weld thickness, crack size, porosity, hot folds, and machining and tooling marks. It provides information on sectioning, sample location, orientation, surface grinding, and etching. It describes macrographic etchants and the features they reveal along with common etching problems and how to avoid them. It explains how to evaluate etching results and how they can be improved using remedial processes such as light grinding. It also discusses photographic reproduction, lighting, and image enhancement techniques.

This chapter provides guidelines for conducting metallographic evaluations and offers suggestions on how to effectively report the results. It explains how the approach depends on the objective of the evaluation, which is usually to measure a structural feature, test a hypothesis, or investigate structure-related effects. The chapter addresses each case, tailoring its guidelines and suggestions accordingly.

This appendix is a compilation of tables helpful to metallographers in characterizing irons and steels. The tables include AISI/SAE designations and specific composition ranges for various steels and irons, listings of companies that sell metallographic equipment and supplies, and compositions and usage guidance for etchants, chemical polishing solutions, and coatings.

This chapter explains the distinction between materials and matter through the concept of microstructure. It presents the history of matter science and the establishment of metallography. The chapter provides an overview of the progress of steel technology, progress in synthetic polymers and ceramics, and establishment and development of materials science.

This chapter discusses the context in which metallography is used and some of the challenges of analyzing three-dimensional structures from a two-dimensional perspective. It describes the hierarchical nature of metals, the formation of grain boundaries, and the notable characteristics of microstructure. It explains how microstructure can be represented qualitatively by points, lines, surfaces, and volumes associated to a large extent with grain contact, and how qualitative features (including grains) can be quantified based on cross-sectional area, volume fraction, density, distribution, and other such metrics.

This chapter provides an overview of the various inspection methods used with metals and alloys, namely visual inspection, coordinate measuring machines, machine vision, hardness testing, tensile testing, chemical analysis, metallography, and nondestructive testing. The nondestructive testing methods discussed are liquid penetrant inspection, magnetic particle inspection, eddy current inspection, radiographic inspection, and ultrasonic testing.

This chapter discusses the effects of hot working on the structure and properties of steel. It explains how working steels at high temperatures promotes diffusion, which helps close cavities and pores, and how it changes the shape and distribution of segregates, offsetting their effect. It describes the effect of hot working on nonmetallic inclusions and the many properties influenced by them. It discusses the recrystallization mechanism by which hot working produces microstructural changes and explains how to control it by adjusting temperature, degree of reduction, and cooling rates. It describes special cases of segregation, including banding and why it occurs, and the application of closed die forging. The chapter also presents several examples of hot working defects, including forging laps, cracks, and overheated or burned steel.

This chapter first introduces the various factors that may alter the physical and mechanical properties of aluminum castings that are addressed in the other chapters in the book. Then, it presents the historical development of aluminum castings, followed by a discussion on the advantages and limitations of aluminum castings. Next, the chapter describes the major trends that are influencing the increased use of aluminum castings. Finally, it introduces the considerations involved in the selection of an appropriate aluminum alloy and casting process for a given application.

This chapter discusses the equipment and processes used to convert titanium billet and bar into useful shapes or more refined product forms. These secondary working operations include open-die, closed-die, hot-die and isothermal forging as well as ring rolling and extruding. The chapter describes each method in detail and how it affects the microstructure and mechanical properties of various titanium alloys. It also discusses the propensity of titanium to react with oxygen and hydrogen when heated and explains how to mitigate the effects.

During fusion welding, the thermal cycles produced by the moving heat source causes physical state changes, metallurgical phase transformations, and transient thermal stresses and metal movement. This chapter begins by discussing weld metal solidification behavior and the solid-state transformations of the main classes of metals and alloys during fusion welding. The main classes include work- or strain-hardened metals and alloys, precipitation-hardened alloys, transformation-hardened steels and cast irons, stainless steels, and solid-solution and dispersion-hardened alloys. The following section provides information on the residual stresses and distortion that remain after welding. The focus then shifts to distortion control of weldments. Inclusions and cracking are discussed in detail. The chapter also discusses the causes for reduced fatigue strength of a component by a weld: stress concentration due to weld shape and joint geometry; stress concentration due to weld imperfections; and residual welding stresses. Inspection and characterization of welds are described in the final section of this chapter.

This chapter describes some of the most effective tools for investigating boiler tube failures, including scanning electron microscopy, optical emission spectroscopy, atomic absorption spectroscopy, x-ray fluorescence spectroscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. It explains how the tools work and what they reveal. It also covers the topic of image analysis and its application in the measurement of grain size, phase/volume fraction, delta ferrite and retained austenite, inclusion rating, depth of carburization/decarburization, scale thickness, pearlite banding, microhardness, and hardness profiles. The chapter concludes with a brief discussion on the effect of scaling and deposition and how to measure it.

This chapter describes the basic steps in the production of titanium ingots and their subsequent conversion to standards product forms. It explains how titanium ore is reduced to a spongy residue, then granularized, compacted, and melted (along with alloying additions) to form an ingot, which may be remelted several times to achieve the necessary properties. It also discusses the cause of defects and ingot imperfections and the benefits of billet reduction and grain-refinement processes.

This chapter discusses the properties and compositions of steels used in pressure vessels, piping, boilers, rebar, and other structural applications. It covers fine-grained steels, quenched and tempered steels, and controlled rolled (thermomechanical treatment) steels. It also compares and contrasts steels used for concrete reinforcement and in various types of pressure vessels, and presents a metallographic study of the effects of welding on the micro and macrostructure of steel.

This chapter serves as a study and guide on the main phase constituents of cast aluminum-silicon alloys, alpha-Al solid solution and Si crystals. The first section focuses on the structure of Al-Si castings in the as-cast state, covering the morphology of the alpha-Al solid solution grains and the process by which they form. It describes how cooling rates, temperature gradients, and local concentrations influence the topology of the crystallization front, and how they play a role in determining the morphology and dispersion degree of the grains observed in cross sections of cast parts. It also describes the mechanism behind dendritic grain crystallization and how factors such as surface tension, capillary length, and lattice symmetry affect dendritic arm size and spacing. The section that follows examines the morphology of the silicon crystals that form in aluminum-silicon castings and its effect on properties and processing characteristics. It discusses the faceted nature of primary Si crystals and the modification techniques used to optimize their shape. It also describes the morphology of the (alpha-Al + Si) eutectic, which can be lamellar or rodlike in shape, and explains how it can be modified through temperature control or alloy additions to improve properties such as tensile strength and plasticity and reduce shrinkage.

This chapter introduces many of the key concepts on which metallurgy is based. It begins with an overview of the atomic nature of matter and the forces that link atoms together in crystal lattice structures. It discusses the types of imperfections (or defects) that occur in the crystal structure of metals and their role in mechanical deformation, annealing, precipitation, and diffusion. It describes the concept of solid solutions and the effect of temperature on solubility and phase transformations. The chapter also discusses the formation of solidification structures, the use of equilibrium phase diagrams, the role of enthalpy and Gibb’s free energy in chemical reactions, and a method for determining phase compositions along the solidus and liquidus lines.