Understanding How Components Fail (Third Edition)
Preface to the First Edition
THIS BOOK IS intended for use primarly by those who have little or no prior knowledge of the principles of metallurgical failures, such as in distortion, fracture, wear, and corrosion. In this sense, it can be considered to be a primer, for many complex technical concepts are explained in relatively simple terms—sometimes oversimplified for ease of understanding.
Failure analysis is a critical first step in identifying a problem that has occurred in a metal component of a mechanism or structure. Once the mode of failure has been identified, appropriate corrective measures may then be taken to try to prevent similar future failures.
Nowhere is the need for accurate failure analysis more dramatically obvious than after an aircraft accident. After a serious crash, trained teams of investigators examine all phases of the aircraft and its operation, seeking clues to the true cause of the accident. Lives literally hang on the accuracy of the failure analysis process.
Failure analysis frequently involves comparing an unexplained failure with examples of failures whose cause has been determined. Identification of fractures, for example, is facilitated by comparing them with photographs of various types of fractures such as those shown in this book. The field of failure analysis is so vast that it encompasses all of metal and metalworking technology. There are many books and articles in the technical literature that deal with all types of failures of virtually all metals. At the end of every chapter in this book are selected references for further study. The serious reader is urged to use these and other references to pursue specific problems beyond the scope of this volume.
There is an infinite variety of types of parts, metals, treatments, conditions, types of loading, applications, environments, and combinations of all of these. Since it is impossible for a single work to cover every conceivable possibility, basic principles are explained with examples using common metals, primarily ferrous. Also, common types of parts are used in the examples, for the principles involved in their analysis may also be applicable to other types of parts not considered.
This work is the distillation of a lifetime of interest in failures and the techniques used to prevent failures, in study of failures, and in teaching others how to identify failures and how to correct them. Failure analysis is a fascinating subject, frequently compared with autopsies in the medical field.
In preparing this book I have had help from many people. Reviewers who read the first draft of each chapter and gave me many valuable suggestions for improvements were F.J. Marcom, J.P. Sheehan, G.H. Walter, and J.L. Welker. E.J. Rusnak and R.W. Morris took many of the photographs that are used. Many other photographs were given to me with the understanding that the contributor not be identified. To all of these persons, and many others who have given assistance, my sincere thanks.
Finally, my wife, Jini, has put up with my erratic schedule and helped me with the proofreading for many months. To her, particularly, my sincere thanks. The effort will have been worth it if this book is able to help many readers understand how components fail.
Fort Wayne, Indiana