This appendix contains sample problems with worked solutions pertaining to the use of binary phase diagrams. The problems require the determination of favorable temperatures and compositions, the amount and composition of phases in an alloy at a given temperature, the amount of a certain phase in different steels, and the microstructure developed in different alloys.

This chapter discusses the crystal structures of steel and cast iron, the iron-iron carbide equilibrium diagram, microconstituents or phases in the iron-iron carbide phase diagram, the iron-carbon carbide-silicon equilibrium diagram of cast irons, and the influence on microstructure by base elements and alloying elements. Graphitization, cooling rates, and heat treatment effects are covered. There also is discussion on inoculation benefits, flake graphite types and typical applications, evolution of cast iron types, ASTM specification A247 for graphite shapes, and selection of the best molding process. A large table lists typical material choices for various applications.

Unlike conventional quench and temper heat treatment, austempering is an iron and steel heat-treatment process that enhances mechanical properties through the isothermal transformation of austenite with a minimum amount of quenching stresses. This chapter begins with a discussion of austemperability requirements. Then outlines of austenitizing and austempering cycles and resultant microstructures are presented. This is followed by sections discussing the mechanical properties, advantages, limitations, machinability, process variants, and applications of austempered ductile iron (ADI). Information on the growth of premachined ADI components is also provided. Further, the chapter describes two slightly different systems for austempering: atmospheric-salt and salt-salt systems. Finally, it presents general guidelines for component designers, casting manufacturers, and heat treaters to apply ADI more widely and with improved success.

The existence of austenite and ferrite, along with carbon alloying, is fundamental in the heat treatment of steel. In view of the importance of structure and its formation to heat treatment, this chapter describes the various microstructures that form in steels, the various factors that determine the formation of microstructures during heat treatment processing of steel, and some of the characteristic properties of each of the microstructures. The discussion also covers the constitution of iron during heat treatment and the phases of heat-treated steel with elaborated information on iron phase transformation, hysteresis in heating and cooling, ferrite and austenite as two crystal structures of solid iron, and the diffusion coefficient of carbon.

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 phases and constituents present in iron-carbon steels in near-equilibrium conditions. It explains how to use phase diagrams to predict and manage the development of ferrite, austenite, cementite, and pearlite through controlled cooling. It discusses the transformations, grain structure, and properties associated with each phase and identifies the primary stabilizing elements. It includes several micrographs revealing various microstructural features and describes the processing route by which they were achieved. It explains how to estimate the volume fraction of iron-carbon phases in equilibrium and how to determine the amount of each phase that must be present to reach a desired composition. The chapter also discusses the phases associated with hypo- and hyper-eutectoid steels and presents more than a dozen micrographs, identifying important structural features along with cooling conditions and sample preparation procedures.

Heat treatment is the most common way of altering the mechanical, physical, and even chemical properties of steels. This chapter describes the changes that occur in carbon and low-alloy steels during conventional heat treatments. It explains how austenite decomposition largely defines the final microstructure, and how the associated phase transformations are driven by nucleation and growth processes. It describes diffusionless and diffusive growth mechanisms and provides detailed information on the properties, structure, and behaviors of the transformation products produced, namely martensite and bainite. It also discusses the formation of austenite, the control and measurement of austenitic grain size, the characteristics of ferritic microstructures, and the methods used to classify ferrite morphology.

This chapter provides an overview of the microstructure-property relationships associated with aluminum-silicon alloys. It includes information on commercial designations and grades, phase compositions, solidification paths, alloying elements, and intermetallic phases. It also provides solubility data and maps out the topics covered in subsequent chapters in the book.

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.

Structurally differentiated intermetallic phases are important constituents in the microstructure of aluminum alloys, with the potential to influence properties, behaviors, and processing characteristics. These phases can form in aluminum-silicon alloys with transition metals (Fe, Mn, Ni, Cr, V, Ti) and with metals such as Mg and Cu. This chapter is a compilation of phase diagrams, microstructure images, and tables, providing information on more than 30 binary, ternary, and quaternary alloy systems associated with intermetallic phases in aluminum-silicon castings. Each section includes tabular information and data on the intermetallic phases in the aluminum corner of the equilibrium phase diagram, the characteristics of the crystal lattice of intermetallic phases, the chemical composition of the alloy intermetallic phases, and equilibrium reactions in the alloy system.

This chapter is an atlas of microstructures observed in AlSi7Mg, AlSi11, and Al21CuNiMg modified with either eutectic (strontium, sodium) or hypereutectic (phosphorus) silicon crystals. The microstructure images reveal the as-cast state of gravity castings made in sand and metal molds, before and after modification. The chapter also provides composition data and includes callouts identifying various phase constituents in the interdendritic eutectic microstructure.

Intermetallic phase precipitates in aluminum alloys can often be identified without resorting to chemical analysis. Very often the determination can be made based on the shape, color, and refractive properties of the particular phase. This chapter explains how these visual attributes can be observed using metallographic techniques. It describes, and in many cases illustrates, the characteristic shapes, colors, and optical properties associated with aluminum alloy intermetallic phases and how they can be enhanced through selective etching. It provides an atlas of microstructures comparing the effects of selective etching procedures on various phase constituents in cast aluminum-silicon alloys. The compilation of images demonstrates the use of two types of reagents: those that reveal discontinuities in crystal orientation and grain boundaries, and those that reveal differences in chemical composition.

This appendix lists the intermetallic phase designations of aluminum-silicon casting alloys and defines symbols and abbreviations associated with the variables, processes, and tools used in microstructural examination.

This chapter discusses the basic principles of alloying and their practical application in the production of titanium mill products and engineered parts. It begins with a review of the atomic and crystal structure of titanium and the conditions for interstitial and substitutional alloying. It then describes the different classes of alloying elements, their effect on mechanical properties and behaviors, and their influence on phase transitions and transformations. The chapter also discusses the role of intermetallic compounds and their effect on crystal structure and creep behavior.

This chapter describes the iron-carbon phase diagram, its modification by alloying elements, and the effect of carbon on the chemistry and crystallography of austenite, ferrite, and cementite found in Fe-C alloys and steels. It also lays the groundwork for understanding important metallurgical concepts, including solubility, critical temperature, dislocation defects, slip, and diffusion, and how they affect the microstructure, properties, and behaviors of steel.

The microstructure of carbon steel is largely determined by the transformation of austenite to ferrite, cementite, and pearlite. This chapter focuses on the microstructures produced by diffusion-controlled transformations that occur at relatively low cooling rates. It describes the conditions that promote such transformations and, in turn, how they affect the structure of various phases and the rate at which they form. The chapter also discusses the concepts of transformation kinetics, minimum free energy, and nucleation and growth, and provides information on alloying, interphase precipitation, and various types of transformations.

The formation of martensite is characterized by its athermal transformation kinetics, crystallographic features, and development of fine structure. This chapter describes the diffusionless, shear-type transformation of austenite to martensite and how it affects the morphology and microstructure of heat-treatable carbon steels. It also provides information on lath and plate martensite and how they differ in structure and deformation properties.

Bainite is an intermediate temperature transformation product of austenite. This chapter describes the conditions under which bainite is likely to form. It discusses the effects of alloying on bainitic transformation, the difference between upper and lower bainite, and the influence of solute drag on bainite formation mechanisms. It also discusses the development of ferrite-carbide bainites and their effect on toughness, hardness, and ductility.