Many companies conduct only metallurgical evaluations in the wake of failures, discovering nothing more than the physical mechanism by which the failure occurred. The origin of failures, however, is often complex, involving not only physical mechanisms, but also human behavior and latent factors. Failures may also involve multiple parts, entire machines, or processes of any size and shape. The chapter examines the unique aspects of many failures and explains how they can sometimes be traced to systemic issues. It also covers the reasons why products fail, including improper service or operation, improper maintenance, improper testing, assembly errors, fabrication or manufacturing errors, and design errors. The case of the Tacoma Narrows Bridge collapse is presented to illustrate the consequence of overlooked factors, in this case, wind dynamics, and the importance of identifying root causes to prevent repeat failures.

A system failure occurs when a system does not do what it is supposed to do when it is supposed to do it, or it does something it is not supposed to do. This chapter provides a basic understanding of how failures occur, how systems operate, and the types of failures, namely intermittent and inadvertent system failures.

This chapter explains what some of the terms used in physical metallurgy are intended to mean and how these meanings affect the manner in which the subject is treated throughout the book.

This chapter focuses on what can cause a system to fail and addresses the challenge in approaching a system failure. It then examines the steps involved in the four-step problem-solving process: defining the problem, identifying all potential failure causes and evaluating the likelihood of each, identifying the potential solutions, and identifying the best solution. The chapter concludes by describing the responsibilities of a failure analysis team.

Failure mode assessment and assignment (FMA&A) is a tool designed to help organize the evaluation of hypothesized failure modes. This chapter begins by describing the process of preparing an FMA&A. It then describes the follow-on activities to evaluate the hypothesized failure cause. The chapter also provides information on evaluating the hypothesized potential causes.

This chapter describes some common pitfalls encountered in failure investigations and provides guidance to help engineers recognize processes and “quick fixes” that companies often try to substitute for failure analysis. It discusses three important skills and characteristics that a professional engineer must improve to conduct an effective and successful failure investigation, namely technical skills, communication skills, and technical integrity. The chapter also provides information on the additional basic tools available for failure investigation and root cause determination: the Kepner-Tregoe structured problem-solving method, PROACT software for root cause analysis developed by the Reliability Center, Inc., and other processes and methods developed by the Failsafe Network, Inc., and Shainin LLC.

Statistics, data analysis, root cause analysis, and problem-solving processes play a key role in failure investigations. This chapter explains how to collect failure investigation data, how to build and maintain a database for company-related failures, and how to use corresponding statistics including type of failure, material, and root cause. It describes the purpose and benefits of conducting a root cause analysis and the factors, namely relative failure importance and company value, that determine when an investigation should be performed. The chapter also discusses the four-step problem-solving process as it applies to failure investigation, how to assemble an investigation team, and the details of organization and planning. It concludes with a case history of the Firestone 500 steel-belted tire failure, stressing the importance of a systematic approach to failure investigations.

Failure investigation is an integral part of any design and manufacturing operation, providing critical information to solve manufacturing problems and assist in redesigns. This chapter addresses several aspects of failure investigation, beginning with the challenges of organizing such efforts and the need to define a clear and concise goal, direction, and plan prior to the investigation. It covers the causes of failure and the training and education organizations require to understand and prevent them. The chapter emphasizes the importance of discovering the root cause of failures, and uses examples to explain the factors involved and how to recognize them when the first appear.

This chapter discusses the operating mechanism, applications, advantages, and limitations of Brinell hardness testing, Rockwell hardness testing, Vickers hardness testing, Scleroscope hardness testing, and microhardness testing. In addition, the general precautions and selection criteria to be considered are described and details of equipment setup provided.

Product design requires an understanding of the mechanical properties of materials, much of which is based on tensile testing. This chapter describes how tensile tests are conducted and how to extract useful information from measurement data. It begins with a review of the different types of test equipment used and how they compare in terms of loading force, displacement rate, accuracy, and allowable sample sizes. It then discusses the various ways tensile measurements are plotted and presents examples of each method. It examines a typical load-displacement curve as well as engineering and true stress-strain curves, calling attention to certain points and features and what they reveal about the test sample and, in some cases, the cause of the behavior observed. It explains, for example, why some materials exhibit discontinuous yielding while others do not, and in such cases, how to determine when yielding begins. It also explains how to determine other properties via tensile tests, including ductility, toughness, and modulus of resilience.

To ensure the proper application of plastics, one must keep in mind three factors that determine the appropriate end-use: material selection, processing, and design. This article begins by providing information on various factors pertinent to the anticipated use conditions of the article to be designed. This is followed by a discussion on several stages necessary to define the geometry of plastic parts. Details on the strength of and cost estimation for plastic parts are then provided. The article ends with a section providing information on the structure, properties, processing, and end-use applications of plastics.

This chapter explains the idea of solution theory and the nature of mixed materials. The chapter considers approximation of free energy by the regular solution model and sublattice model. It discusses chemical potential and nonrandom distribution based on the interactions between solute atoms.

The need for precise targeted interactive surgery on boards or modules is the main driver of backside preparation technology. This article assists the analyst in making decisions on backside thinning and polishing requirements. Thinning of the substrates can be accomplished by flat lapping, laser assisted chemical etch, plasma reactive ion etch, and CNC based milling and polishing. The article discusses the general characteristics, key principles, advantages, and disadvantages of these processes. It also contains case studies that illustrate the application of these processes to ceramic cavity devices, injection molded parts, and ball grid arrays.

Several specialized instruments are available for the metallographer to use as tools to gather key information on the characteristics of the microstructure being analyzed. These include microscopes that use electrons as a source of illumination instead of light and x-ray diffraction equipment. This chapter describes how these instruments can be used to gather important information about a microstructure. The instruments covered include image analyzers, transmission electron microscopes, scanning electron microscopes, electron probe microanalyzers, scanning transmission electron microscopes, x-ray diffractometers, microhardness testers, and hot microhardness testers. A list of other instruments that are usually located in a research laboratory or specialized testing laboratory is also provided.

This chapter explains the significance of the phase diagram and its use in the development of new materials. The chapter describes the basic rules of heterogeneous equilibrium, presents a comparison between liquidus line and solidus line, and provides information on the solubility curve and the binodal curve.

This chapter reviews various ways to classify failure categories and summarizes the basic types, causes, and mechanisms of damage, with particular consideration given to whether the likelihood of the types of damage can or cannot be influenced by the heat treating of steel parts. The classical organization for types of damage (failures) is as follows: deformation, fracture, wear, corrosion or other environmental damage, and multiple or complex damage. The chapter also provides some examples of lack of conformance to specification that may at first look like the heat treater did something wrong, but where other contributing factors made it difficult or impossible for the heat treater to meet the specification.

This chapter discusses the processes and procedures involved in tribotesting, the significance of test parameters and conditions, and practical considerations including test metrics and measurements and the interpretation of wear damage. It also describes the different types of erosion tests in use and common approaches for adhesive wear and abrasion testing.

A systematic procedure for minimizing risks involved in heat treated steel components requires a combination of metallurgical failure analysis and fitness for service with respect to safety and reliability based on risk analysis. This chapter begins with an overview of heat treat processing of steels. This is followed by sections on various aspects of heat treatment design and heat treating practices for minimizing distortion. Influence of design, steel grade, and condition is then illustrated in the examples of failures due to heat treatment. A procedure is analyzed to improve the performance of the design process of a component. A heat-transfer model, coupling with a phase transformation model, a thermomechanical model, and a thermochemical model, is also considered. The chapter further provides information on the failure aspects of and heat treatment procedures applied to welded components. It ends with a section on risk-based approach applicable to heat treated steel components.

This chapter instructs the metallographer on the basic skills required to prepare a polished metallographic specimen. It is organized in a chronological sequence starting with the information-gathering process on the material being investigated, then moving on to sectioning, mounting, grinding, and polishing processes, and ending with methods used to properly store metallographic specimens. The discussion covers the preparation procedures, the materials being investigated, and equipment used to perform these procedures.