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.

This chapters discusses the basic steps in the failure analysis process. It covers examination procedures, selection and preservation of fracture surfaces, macro and microfractography, metallographic analysis, mechanical testing, chemical analysis, and simulated service testing.

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.

This chapter describes the nine steps of a failure investigation. The steps add detail to the problem-solving process introduced in Chapter 3. The first five steps are (1) understanding and negotiating the investigation goals, (2) obtaining an understanding of the failure, (3) objectively and clearly identifying all possible root causes, (4) evaluating the likelihood of each root cause, and (5) converging on the most likely root cause(s). Many failure investigations stop at this point, but significant value is provided in the next four steps, which are (6) identifying all possible corrective actions, (7) evaluating each corrective action, (8) selecting the optimal corrective action(s), and (9) evaluating the effectiveness of each corrective action. Each step is discussed in detail with examples along with information on the procedures to be followed and resources needed for the investigation.

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.

This article introduces the subject of fractography and how it is used in failure analysis. The discussion covers the structure of and fracture and crack-propagation behavior of polymeric materials, the distinction between the ductile and brittle fracture modes on the basis of macroscopic appearance, and the examination and interpretation of the features of fracture surfaces. In addition, the article considers several cases of field failure in various polymers to illustrate the applicability of available analytical tools in conjunction with an understanding of failure mechanisms.