This chapter addresses the basic concepts important to understanding corrosion of metals. It begins with an overview of the three types of behaviors that a metal exhibits when immersed in an environment and of the four requirements of a corrosion cell. The chapter then covers the important characteristics of metals with respect to corrosion, namely the metallurgical characteristics, the inherent tendency to corrode, and the tendency to form insoluble corrosion products. The important characteristics of aqueous solutions with respect to corrosion are then addressed. The characteristics include: conductivity of the solution, acidity and alkalinity, oxidizing power, degree of ionization, and solubility in the solution. These characteristics, in combination with the characteristics of the metal, will determine the corrosion behavior of a metal/environment combination. The chapter concludes with a section on the determination of corrosion rates and corrosion rate allowances.

The design stresses for most pressure-containing structural application, which are based upon minimum mechanical properties designated in the specifications published by the American Society for Testing and Materials (ASTM). This chapter reviews metallurgical characteristics and their influence on the properties and performance of structural carbon and low alloy steels and contains a summary of the relevant features of the ASTM product specifications.

This chapter discusses field, visual, physical, and metallurgical examinations of gear failures. Physical examinations reviewed include nondestructive testing, including magnetic-particle inspection, tooth characteristic studies, surface hardness testing, ultrasonic testing, nital etching, profilometer measurements, and dimensional checking. Metallurgical examinations reviewed include the cross-sectional hardness survey, macroscopic examination, carbon gradient traverse, chemical analysis, case hardness traverse [microhardness], microscopic examination, and scanning electron microscopy.

This chapter discusses the various factors influencing the evaluation of fatigue fracture of nitrided layers. It begins by describing the problems of enhancing the fatigue resistance of machine components. The significance and detailed assessment of the effect of a structural flaw are then explained, using investigations of the effect of variable core conditions on fatigue resistance as an example. This is followed by a discussion on the processes involved in the evaluation of fatigue properties of nitrided steels. The chapter also describes the determination of the fatigue characteristics of nitrided steels after the carbonitriding treatment.

This appendix focuses on procedures, techniques, and precautions associated with the investigation and analysis of metallurgical failures that occur in service. It describes the steps of an orderly failure analysis from collecting and examining samples to performing mechanical and nondestructive tests, preparing and examining fractographs and micrographs, determining failure mode, writing the report, and developing follow-up recommendations. It also examines the fundamental mechanisms of failure, why they occur, and how to identify them by their characteristic features.

Brazing and soldering processes use a molten filler metal to wet the mating surfaces of a joint, with or without the aid of a fluxing agent, leading to the formation of a metallurgical bond between the filler and the respective components. This chapter discusses the characteristics, advantages, and disadvantages of brazing and soldering. The first part focuses on the fundamentals of the brazing process and provides information on filler metals and specific brazing methods. The soldering portion of the chapters provides information on solder alloys used, selection criteria for base metal, the processes involved in precleaning and surface preparation, types of fluxes used, solder joint design, and solder heating methods.

This chapter discusses various types of material fracture toughness and the methods by which they are determined. It begins with a review of the basic principles of linear elastic fracture mechanics, covering the Griffith-Irwin theory of fracture, the concept of strain energy release rate, the use of fracture indices and failure criteria, and the ramifications of crack-tip plasticity in ductile and brittle fractures. It goes on to describe the different types of plain-strain and plane-stress fracture toughness, explaining how they are measured and how they are influenced by metallurgical and environmental variables and loading conditions. It also examines the crack growth resistance curves of several aluminum alloys and describes the characteristics of fracture when all or some of the applied load is in the plane of the crack.

Carbon and low-alloy steels are the most frequently welded metallic materials, and much of the welding metallurgy research has focused on this class of materials. Key metallurgical factors of interest include an understanding of the solidification of welds, microstructure of the weld and heat-affected zone (HAZ), solid-state phase transformations during welding, control of toughness in the HAZ, the effects of preheating and postweld heat treatment, and weld discontinuities. This chapter provides information on the classification of steels and the welding characteristics of each class. It describes the issues related to corrosion of carbon steel weldments and remedial measures that have proven successful in specific cases. The major forms of environmentally assisted cracking affecting weldment corrosion are covered. The chapter concludes with a discussion of the effects of welding practice on weldment corrosion.

Discontinuities are interruptions in the desirable physical structure of a weld. This article describes the types of weld discontinuities that are characteristic of the principal welding processes. Discontinuities covered are metallurgical discontinuities, discontinuities associated with specialized welding processes, and base metal discontinuities. In addition, information on the common inspection methods used to detect these discontinuities is provided.

This chapter explains how to take the known facts of a specific failure, place them in a systematic context to arrive at a logical conclusion, and point to a corrective measure. It presents example examinations to describe a systematic approach to failure examination.

This chapter discusses the various methods used to join titanium alloy assemblies, focusing on welding processes and procedures. It explains how welding alters the structure and properties of titanium and how it is influenced by composition, surface qualities, and other factors. It describes several welding processes, including arc welding, resistance welding, and friction stir welding, and addresses related issues such as welding defects, quality control, and stress relieving. The chapter also covers mechanical fastening techniques along with adhesive bonding and brazing.

A successful heat treating operation is determined by the ability to satisfy the customer's quality requirements consistently and economically. This chapter reviews the steps that are important to produce quality parts in heat treating with a brief practical explanation of each. The steps include selecting proper material and design of the part being treated; determining whether the process is capable of heat treatment; using statistical process control, control charting, and in-process inspection and testing; and applying statistical quality control and final testing (sampling) to verify the results.

This chapter discusses the factors influencing the corrosion resistance of bulk materials, namely alloying, metallurgical factors, and mechanical treatments.

This appendix includes selected references on topics related to the production and application of superalloys, including properties and microstructure; melting/ingot breakdown; forging/powder metallurgy; machining, heat treating, joining, refurbishment/repair; investment casting; coatings/corrosion; and modeling.

This chapter begins with information on the historical development of aluminum alloy castings. It then covers the basic factors involved in the selection of a casting process. This is followed by sections describing the various categories of casting processes and their variants: expendable mold gravity-feed casting, nonexpendable (permanent) mold gravity feed casting, and pressure die casting. Next, the chapter describes the technologies used to produce premium engineered castings and when such castings may be relevant. The chapter concludes with descriptions of other process technologies used with castings, including metallurgical bonding, metal-matrix composites, and hot isostatic pressing.

This chapter provides a detailed discussion on five occasions that require written accounts. They are field report, transmittal report with failed unit, laboratory notes of the analyst, failure analysis report, and letter of transmittal of the report to the customer.

This chapter discusses the role of failure analysis in cases involving product liability, property damage, and personal injury litigation. It also explains how material science and technology shed light on criminal activities such as smuggling, counterfeiting, theft, and the willful destruction of property.

Many factors must be considered when welding dissimilar metals, and adequate procedures for the various metals and sizes of interest for a specific application must be developed and qualified. Most combinations of dissimilar metals can be joined by solid-state welding (diffusion welding, explosion welding, friction welding, or ultrasonic welding), brazing, or soldering where alloying between the metals is normally insignificant. This chapter describes the factors influencing joint integrity and discusses the corrosion behavior of dissimilar metal weldments.

This chapter provides an introduction to metal forming processes and where they fit among the five general areas of manufacturing. It also discusses the basic differences between bulk deformation and sheet-metal forming processes and how they relate to hybrid forming processes such as drawing, bending, and coining.

Elevated-temperature failures are the most complex type of failure because all of the modes of failures can occur at elevated temperatures (with the obvious exception of low-temperature brittle fracture). Elevated-temperature problems are real concerns in industrial applications. The principal types of elevated-temperature failure mechanisms discussed in this chapter are creep, stress rupture, overheating failure, elevated-temperature fatigue, thermal fatigue, metallurgical instabilities, and environmentally induced failure. The causes, features, and effects of these failures are discussed. The cooling techniques for preventing elevated-temperature failures are also covered.