Steel heated in contact with air at temperatures in the tempering range takes on various temper colors due to the formation of a thin oxide film. This appendix provides information on the cause and source of oxidation of steel and time-temperature effect on SAE 1035 steel. In addition, figures that show temper colors after heating 1035 steel in circulating air are presented.

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 chapter discusses the functions of surface treatments important for stainless steel, namely the removal of oxide scale and cleaning, brightening, and coloring of the stainless surface. Details on the main methods of producing aesthetic surface finishes are also provided.

Most steels that are hardened are subjected to a subcritical heat treatment referred to as tempering. Tempering improves the toughness of as-quenched martensitic microstructures but lowers strength and hardness. This chapter describes the microstructural changes that occur during tempering and their effect on the mechanical properties of steel. It also discusses the effect of alloying elements and the formation of oxide colors.

This article is a brief account of various factors pertinent to the characterization of materials and analysis of optical components, namely transmission, haze, yellowness, refractive index, surface irregularity, birefringence, internal contamination, surface gloss, and color. In addition, details on ad hoc tests used for determining the acceptability of a plastic part for its application are provided, along with typical examples.

Temperature is a critical process parameter in the heat treatment and forging of steel and must be accurately measured to properly control it. This appendix discusses the operating principles of thermocouples and infrared pyrometers, describing the various types as well as advantages and applications.

This chapter discusses the tools and techniques of light microscopy and how they are used in the study of materials. It reviews the basic physics of light, the inner workings of light microscopes, and the relationship between resolution and depth of field. It explains the difference between amplitude and optical-phase features and how they are revealed using appropriate illumination methods. It compares images obtained using bright field and dark field illumination, polarized and cross-polarized light, and interference-contrast techniques. It also discusses the use of photometers, provides best practices and recommendations for photographing structures and features of interest, and describes the capabilities of hot-stage and hot-cell microscopes.

This chapter explains how to achieve accurate, sharp delineation of the microstructure of metals using appropriate etching and contrasting techniques. It covers a variety of methods, including chemical etching, heat tinting, gas contrasting, vapor deposition, magnetic etching, ion bombardment, and dislocation etch pitting.

This chapter reviews the nomenclature of different vehicle components helpful in identifying the target applications and discusses the implementation of advanced high-strength steels (AHSS) in automotive and nonautomotive industries. In addition, the chapter provides information on the utilization and trends of AHSS in vehicle bodies and closures.

This chapter describes the methods and equipment applicable to metallographic studies and discusses the preparation of specimens for examination by light optical microscopy. Five major operations for preparation of metallographic specimens are discussed: sectioning, mounting, grinding, polishing, and etching. The discussion covers their basic principles, advantages, types, and applications, as well as the equipment setup. The chapter includes tables that list etchants used for microscopic examination. It also provides information on microscopic examination, microphotography, and the effects of grain size on the structural properties of the material.

Most quenched steels are tempered because the toughness of as-quenched steels is generally very poor. The tempering operation sacrifices strength for improvements in ductility and toughness. This chapter discusses the tempering process, the challenge of tempered martensite embrittlement, and the effect of wt% carbon on toughness. It also explains how alloying elements improve the hardenability and tempering response of plain carbon steels.

This chapter describes the various features of the metallurgical microscope. Key concepts are defined such as resolving power, the virtual image, bright- and dark-field illumination, numerical aperture, focal length, image contrast, depth of field, and spherical and chromatic aberration. Metallurgical microscope features such as apochromatic objectives, hyperplane oculars, vertical illuminators, counting reticles, widefield oculars, polarization filters, field diaphragms, interferometers, and tungsten-halogen lamps are explained. The optical system, nosepiece, types of objectives (the lens assembly close to the specimen) and eyepieces, and components of the illumination system are all explained. The last part of this chapter describes special procedures involved in using and calibrating the metallurgical microscope.

This chapter discusses the important aspects that a metallographer should understand in order to effectively reveal a microstructure. It begins by exploring etching response and how it can be a tool for revealing various microstructural features. The next part of the chapter discusses methods for revealing microstructure in the as-polished (unetched) specimen, then guidelines for selecting and using etchants when needed. The chapter discusses different types of etchants in terms of their ingredients, etching procedure, and major uses. The etchants discussed include basic etchants (nital and picral and their variations) and tint etchants for carbon and low-alloy steels and cast irons, and basic etchants for stainless steels. Finally, information is provided on different illumination methods (differential interference contrast and dark-field illumination) that can be used to highlight certain features in microstructures.

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 explains how to safely prepare beryllium alloy samples for metallographic analysis. It describes grinding, polishing, and etching procedures in detail. It also discusses the identification of major and minor constituents and the general appearance of beryllium microstructure.

This appendix provides information on the chemical composition, method of use, and applications of various etchants used in the metallography of carbon steels.

This chapter explains how to prepare material samples for optical microscopy, the most common method for characterizing the microstructure of cast iron and steel. It provides information on sectioning, mounting, polishing, etching, and recording. It describes the nature of surface roughness, the factors that contribute to it, and its effect on image quality. It discusses the use of fixturing and holding devices, includes photographic examples of polishing defects and drying marks, and provides an overview of micrographic etchants and the features they reveal. It also describes the steps involved in replicating part surfaces.

In the second step of the four-step problem-solving process, the failure analysis team should identify all potential failure causes. This chapter discusses the steps involved in five such techniques for identifying potential causes of failure, namely brainstorming, mind mapping, Ishikawa diagrams, the “five whys” technique, and flow charting.