Practices in Failure analysis Introduction ANALYZiNg the inevitable failures that occur during testing. manufacturing. and service is an essential ngineering process for continual improvement in product reliability. This article describes the general procedures, techniques, and precautions employed in the investigation and analysis of metallurgical failures that occur in service. The stages of investigation are discussed. and the various features of the more common causes of failure characteristics are described for fracture. corrosion and wear failures The mechanisms of fracture corrosion, and wear failures are explained in more detail in other Sections of this volume Practices in Failure Analysis Stages of a Failure Analysis Although the sequence is subject to variation depending on the nature of the failure and the availability of physical evidence or background information, there are stages that are common to all successful failure analyses. The combination of these stages comprises the total investigation and analysis. The following list includes many of the commonly used stages. The sequence in which these stages are used is not necessarily critical, and not all of the stages will or can be used in every failure analysis. However, a key principle is to not unnecessarily disrupt conditions that may require closer examination at a later date. Moreover, an additional constraint is to follow the Federal Rules of Evidence during investigation of a failure that may be destined for The stages discussed in this article begin first with the preliminary steps of information gathering such Collection of background data and selection of samples Preliminary examination of the failed part(visual examination and record keeping) Nondestructive testing These preliminary steps may then be followed by assessment of the damage and conditions leading to failure investigated. In an analysis of a fracture, the following steps are described and/or wear conditions are being These stages may differ depending on whether fracture, corrosion, Selection, identification, preservation, and/or cleaning of critical specimens Macroscopic examination and analysis (fracture surfaces, secondary cracks, and other surface nomen Microscopic examination and analysis of fracture surfaces Stress analysis to determine the actual stress state of the failed component Fracture mechanic Determination of the fracture mode Following these topics on the analysis of fractures, separate sections also briefly describe factors and methods in the analysis of corrosion and wear failures In addition, investigations of a failure may utilize various techniques to characterize the condition of material These include Metallography or microstructural analy Mechanical testingPractices in Failure Analysis Introduction ANALYZING the inevitable failures that occur during testing, manufacturing, and service is an essential engineering process for continual improvement in product reliability. This article describes the general procedures, techniques, and precautions employed in the investigation and analysis of metallurgical failures that occur in service. The stages of investigation are discussed, and the various features of the more common causes of failure characteristics are described for fracture, corrosion, and wear failures. The mechanisms of fracture, corrosion, and wear failures are explained in more detail in other Sections of this Volume. Practices in Failure Analysis Stages of a Failure Analysis Although the sequence is subject to variation depending on the nature of the failure and the availability of physical evidence or background information, there are stages that are common to all successful failure analyses. The combination of these stages comprises the total investigation and analysis. The following list includes many of the commonly used stages. The sequence in which these stages are used is not necessarily critical, and not all of the stages will or can be used in every failure analysis. However, a key principle is to not unnecessarily disrupt conditions that may require closer examination at a later date. Moreover, an additional constraint is to follow the Federal Rules of Evidence during investigation of a failure that may be destined for court. The stages discussed in this article begin first with the preliminary steps of information gathering such as: · Collection of background data and selection of samples · Preliminary examination of the failed part (visual examination and record keeping) · Nondestructive testing These preliminary steps may then be followed by assessment of the damage and conditions leading to failure. These stages may differ depending on whether fracture, corrosion, and/or wear conditions are being investigated. In an analysis of a fracture, the following steps are described: · Selection, identification, preservation, and/or cleaning of critical specimens · Macroscopic examination and analysis (fracture surfaces, secondary cracks, and other surface phenomena) · Microscopic examination and analysis of fracture surfaces · Stress analysis to determine the actual stress state of the failed component · Fracture mechanics · Determination of the fracture mode Following these topics on the analysis of fractures, separate sections also briefly describe factors and methods in the analysis of corrosion and wear failures. In addition, investigations of a failure may utilize various techniques to characterize the condition of material. These include: · Metallography or microstructural analysis · Mechanical testing