Temperature and deformation gradients developed in the course of manufacturing can have undesired effects on the microstructures along their path; the two most common being residual stress and distortion. This chapter discusses these manufacturing-related problems and how they can be minimized by heat treatments. It also provides information on residual stress evaluation and prediction techniques.

This chapter reviews weld corrosion in three key application areas: petroleum refining and petrochemical operations, boiling water reactor piping systems, and components used in pulp and paper plants. The discussion of each area addresses general design and service characteristics, types of weld corrosion issues, and prevention or mitigation strategies.

Fatigue failures occur due to the application of fluctuating stresses that are much lower than the stress required to cause failure during a single application of stress. This chapter describes three basic factors that cause fatigue: a maximum tensile stress of sufficiently high value, a large enough variation or fluctuation in the applied stress, and a sufficiently large number of cycles of the applied stress. The discussion covers high-cycle fatigue, low-cycle fatigue, and fatigue crack propagation. The chapter then discusses the stages where fatigue crack nucleation and growth occurs. It describes the most effective methods of improving fatigue life. The chapter also explains the effect of geometrical stress concentrations on fatigue. In addition, it explores the environmental effects of corrosion fatigue, low-temperature fatigue, high-temperature fatigue, and thermal fatigue. Finally, the chapter discusses a number of design philosophies or methodologies to deal with design against fatigue failures.

The mechanical behavior of a material is its response to an applied load or force. Important mechanical properties are strength, hardness, stiffness, and ductility. This chapter discusses three principal ways in which these properties are tested: tension, compression, and shear. Important tensile properties that can be determined by the tensile test include yield strength, ultimate tensile strength, ductility, resilience, and toughness. The chapter describes the effects of stress concentrations on ductile metals under cyclic loads. Other topics covered include combined stresses, yield criteria, and residual stresses of metals.

This chapter discusses the stress-strain response of materials, how it is measured, and how it used to set performance expectations. It begins by describing the common tensile test and how it sheds light on the elastic design of structures as well as plasticity and fracture behaviors. It explains how engineering and true stress-strain curves differ, how one is used for design and the other for analyzing metal forming operations. It discusses the effect of holes, fillets, and radii on the distribution of stresses and the use of notch tensile testing to detect metallurgical embrittlement. The chapter also covers compression, shear, and torsion testing, the prediction of yielding, residual stress, and hardness.

Residual, or locked-in internal, stresses are regions of misfit within a metal part or assembly that can cause distortion and fracture just as can the more obvious applied, or service, stresses. This chapter describes the fundamental facts about residual stresses and discusses the basic mechanisms of residual stress formation: thermal, transformational, mechanical, and chemical.

This appendix provides detailed information on design deficiencies, material and manufacturing defects, and service-life anomalies. It covers ingot-related defects, forging and sheet forming imperfections, casting defects, heat treating defects, and weld discontinuities. It shows how application life is affected by the severity of service conditions and discusses the consequences of using inappropriate materials.

Some gears may need to be hardened only at the surface without altering the chemical composition of the surface layers. Induction hardening may be a suitable processing choice in these cases. This chapter provides information on the wide variety of materials that can be induction hardened and on process details involved in induction hardening gears. It discusses the processes involved in heating, quenching, and tempering of gears. Information on surface hardness and case depth after induction hardening, induction hardening problems, the applications of induction hardening gears, and the advancements in induction hardening are also provided.

This chapter examines the stress-corrosion cracking (SCC) failure of stainless steel pipe welds in boiling water reactor (BWR) service. It explains where most of the failures have occurred and provides relevant details about the materials of construction, fabrication techniques, environmental factors, and cracking characteristics. It includes a model that accounts for the primary factors involved in intergranular SCC, namely, tensile stresses above the yield stress of the base material, a sensitized microstructure, and reactor cooling water. The chapter also provides proven remedies and mitigation techniques corresponding to a wide range of issues related to stress, sensitization, and operating conditions.

This chapter discusses the factors that play a role in fatigue failures and how they affect the service life of metals and structures. It describes the stresses associated with high-cycle and low-cycle fatigue and how they differ from the loading profiles typically used to generate fatigue data. It compares the Gerber, Goodman, and Soderberg methods for predicting the effect of mean stress from bending data, describes the statistical nature of fatigue measurements, and explains how plastic strain causes cyclic hardening and softening. It discusses the work of Wohler, Basquin, and others and how it led to the development of a strain-based approach to fatigue and the use of fatigue strength and ductility coefficients. It reviews the three stages of fatigue, beginning with crack initiation followed by crack growth and final fracture. It explains how fracture mechanics can be applied to crack propagation and how stress concentrations affect fatigue life. It also discusses fatigue life improvement methods and design approaches.

A brittle fracture occurs at stresses below the material's yield strength (i.e., in the elastic range of the stress-strain diagram). This chapter focuses on brittle fracture in metals and, more specifically, ferrous alloys. It lists the factors that must all be present simultaneously in order to cause brittle fracture in a normally ductile steel. The chapter then discusses the macroscale characteristics and microstructural aspects of brittle fracture. A summary of the types of embrittlement experienced by ferrous alloys is presented. The chapter concludes with a brief section providing information on mixed fracture morphology.

This article reviews fatigue test methodologies, provides an overview of general fatigue behavior (crack initiation and propagation) in engineering plastics, and discusses some of the factors affecting the fatigue performance of polymers. In addition, it provides information on fractography that provides useful insight into the nature of fracture processes.

Metals are used in many engineering applications because of their mechanical properties, particularly strength and ductility. This chapter explains how mechanical properties are measured and how to interpret the results. It describes the most widely used tests, including tensile tests; Rockwell, Brinell, Vickers, and Knoop hardness tests; and Charpy V-notch impact tests. The chapter also provides information on loading conditions that can lead to fatigue failure, and in some cases, counteract or prevent it.

This chapter provides an overview of the possible mechanisms of failure for heat treated steel components and discusses the techniques for examining fractures, ductile and brittle failures, intergranular failure mechanisms, and fatigue. It begins with a description of the general sources of component failure. This is followed by a section on the stages of a failure analysis, which can proceed one after the other or occur at the same time. These stages of analysis are collection of background data, preliminary visual examination, nondestructive testing, selection and preservation of specimens, mechanical testing, macroexamination, microexamination, metallographic examination, determination of the fracture mechanism, chemical analysis, exemplar testing, and analysis and writing the report. The chapter ends with a discussion on various processes involved in the determination of the fracture mechanism.

Failure analysis of steel welds may be divided into three categories. They include failures due to design deficiencies, weld-related defects usually found during inspection, and failures in field service. This chapter emphasizes the failures due to various discontinuities in the steel weldment. These include poor workmanship, a variety of hydrogen-assisted cracking failures, stress-corrosion cracking, fatigue, and solidification cracking in steel welds. Hydrogen-assisted cracking can appear in four common forms, namely underbead or delayed cracking, weld metal fisheyes, ferrite vein cracking, and hydrogen-assisted reduced ductility.

This chapter discusses the fatigue behavior of bolted, riveted, and welded joints. It describes the relative strength of machined and rolled threads and the effect of thread design, preload, and clamping force on the fatigue strength of bolts made from different steels. It explains where fatigue failures are likely to occur in cold-driven rivet and friction joints, and why the fatigue strength of welded joints can be much lower than that of the parent metal, depending on weld shape, joint geometry, discontinuities, and residual stresses. The chapter also explains how to improve the fatigue life of welded joints and discusses the factors that can reduce the fracture toughness of weld metals.

Induction and flame hardening are methods of hardening the surfaces of components, usually in selected areas, by the short-time application of high-intensity heating followed by quenching. These processes are used when gear teeth require high hardness, but size or configuration does not lend itself to carburizing and quenching the entire part. This chapter focuses on the processes involved in the induction and flame hardening, covering the applicable materials, hardening patterns, preheat treatment, quenching, tempering, surface hardness, case depth, hardening problems, dual-frequency process, and applications.

This chapter focuses on the causes of gear failure under five major headings. These include basic material, focusing on steel, engineering, focusing on the integration of design, manufacturing, heat treatment, and service application.