This article provides a discussion on the corrosion of industrial refractory materials and technical ceramics. These materials, which are used to minimize heat losses and provide a barrier between the vessel and its contents, are utilized in the metallurgical, chemical process, power generation, automotive, and aerospace industries. The article covers the fundamental principles of chemical corrosion of refractories and ceramics, and the use of thermodynamic calculations and kinetic models to evaluate the probability of the occurrence of corrosion-causing chemical reactions. It describes the corrosion resistance characteristics of specific classes of refractories and structural ceramics. The article also examines the prevention strategies that minimize corrosion failures of both classes of materials.

This article discusses fractures and cracks due to ancient artifact weaknesses. It provides several case studies to aid the appreciation of fractography as a diagnostic technique and to understand the importance of cracking. These case histories concern ancient gold and silver alloys, bronzes, and wrought irons. The article considers the applicabilities of fractography, metallography, and chemical analyses in answering archaeological and archaeometallurgical questions. The article also discusses the restoration and conservation of corroded and embrittled artifacts, including the use of coatings.

This article addresses macroscale fracture appearances, microscale fracture-surface appearances or morphologies, fracture mechanisms, and those factors that influence fractures and fracture appearances. Some of the macroscopic and microscopic features identified by the failure analyst to evaluate the fracture surfaces of metals and plastics are described and compared.

With regard to documentation and photography of a catastrophic event, the field investigator's duties are fundamentally different from those of the laboratory-based analyst, even though both share the same goals. This article presents a case study on documentation considerations during the field investigation. It provides a detailed discussion on the general procedure to downselect from a multicomponent assemblage to a set of potential primary failed components. The article describes visual examination in macrofractography.

Fracture surfaces can provide an important and indispensable record of many factors in simple or complex failures. Visual examination of fracture surfaces can reveal the type and direction of loading, with fracture-surface features often providing definitive evidence of torsion, tension, bending, and compressive loads. This article discusses tools and techniques of visual examination and characteristic features of fracture features. A brief review of ductile and brittle fracture-surface features is provided. The article also describes macroscopic features that can be used to identify fracture-initiation sites, locations of final overload, and the directions of crack propagation. In addition, the use of these features to characterize loading at the time of failure is also described.

The introduction of focused ion beam (FIB) microscopy in the 1990s added the capability of studying fracture surfaces in the third dimension and making site-specific and stress-free transmission electron microscope (TEM) specimens in situ. This article reviews the methods for preparing replicas and the site-specific FIB thin-foil preparation technique. It provides an overview of FIB-TEM specimen preparation.

Quantitative fractography (QF) is the examination and characterization of fracture surfaces of failed or broken-open components and specimens. This article provides examples of the application of QF to evaluate real-life fatigue failures and also a comprehensive guideline chart for detecting and measuring fatigue striations and progression markings, with examples.

This article presents the concept of fracture mechanisms in general terms in order to impart a practical understanding as well as enable readers to develop the ability to identify the basic fracture mechanisms correctly based on microscope observations. The key microscopic features of fracture surfaces are described and illustrated for the important types of fracture mechanisms. It provides a detailed discussion on environmentally assisted crack initiation and growth.

This article reviews the historical development of fractography, from the early studies of fracture appearance dating back to the sixteenth century, and including the development of microfractography in the middle of the 20th century, to the current state-of-the-art work in electron fractography and quantitative fractography.

This article provides practical guidance for interpreting macroscale fracture appearances. It focuses on metallic fracture features. The article covers the important distinctions between ductile and brittle fracture and the influence of the type of loading on the facture-surface orientation. It discusses both ductile fracture and brittle fracture macroscale features. Finally, it delves into fracture-initiation sites and metal-processing effects on fracture appearance, including castings, powder metals, additive manufacturing, and surface treatments.

Identification of the fracture mechanism is one of the principal responsibilities of a failure analyst and is an important component of any root-cause analysis. This article explores the varied mechanisms responsible for metal fracture, particularly regarding fractography. The behavior of engineering materials at fracture is based on a large number of interrelated characteristics from the atomic level to the component level. These characteristics range from ductile to brittle at the microscale and macroscale levels. Fundamental relative ductility results from the type of electronic bonding, the crystal structure, and the broader long-range degree of order. It provides detailed discussion on ductile fracture, brittle fracture, mixed fracture, embrittlement, stress-corrosion cracking.

This article describes the general factors that can influence fracture appearances. The focus is on the general practical relationships of fracture appearances, with factors presented in some broad categories, including: material conditions (e.g., crystal structure and microstructure); loading conditions (stress state, strain rate, and fatigue); manufacturing conditions (casting, metal-working, machining, heat treatment, etc.); and service and environmental factors (hydrogen embrittlement, stress corrosion, temperature, and corrosion fatigue).

This article provides a discussion on the following photographic equipment: point-and-shoot cameras, digital single-reflex cameras, stand-mounted digital zoom cameras, and digital microscope cameras. It presents two principal types of optical microscopes that are appropriate for visual examination of fractured parts: the stereomicroscope and the single-light-path digital microscope. The common features present on fracture surfaces are each considered separately, both in their significance and as photographic challenges. The article also presents a short note on low-magnification scanning electron microscopy and postcapture image processing.

This article discusses the importance of the care and handling of fracture specimens and what to look for during the preliminary field or laboratory observation and collection, the preservation of specimens, and the cleaning and preparation of fracture specimens for additional analyses. The preservation of nonmetallic specimens, medical devices, oversized components, light alloys, nondestructively tested components, and materials that are part of legal proceedings is addressed.

This article presents a basic overview of technology-driven advances in the imaging of primarily metallic fracture surfaces. It describes various types of microscopes, including scanning electron, dual-beam, ion source, and transmission electron microscopes, and their capabilities. It also covers other useful hardware, such as computer-aided tomography (CAT) and micro-computer-aided tomography (micro-CAT) instruments. The article introduces some of the fracture image postprocessing methods and software, including image registration or alignment, focus stacking, Z-stacking, focal plane merging, and image stitching.

This article presumes the reader has a basic understanding of the operation and principles of scanning electron microscopy (SEM). The emphasis of this article is specifically on the application of SEM to the study of metallic and nonmetallic fracture surfaces, where the typical objectives of SEM examination of a fracture surface may include the following: identification of characteristic fracture features to aid in identifying fracture mechanism(s); characterization of material anomalies that may have influenced the fracture; qualitative or semiquantitative chemical analysis of component material(s); and qualitative or semiquantitative analysis of deposits or corrosion products on or near fracture surfaces.

The development of quantitative fractography (QF) parameters basically requires topological data of a fracture surface that can be derived from the stereological analysis of multiple projected scanning electron microscope (SEM) images; the profilometry-based techniques that measure the fracture surface profile along x-y sections of a fracture surface from metallographic sections or nondestructive techniques; and the three-dimensional reconstruction of the fracture surface topology using imaging methods such as stereo SEM imaging and confocal scanning laser microscopy. These three general methods of assessing fracture surface topology are reviewed in this article.

This article discusses several examples of fatigue load histories that intentionally create artificial fracture-surface markings during testing such that they are measurable by post-test quantitative fractography (QF). It reviews a number of methods for providing fatigue fracture-surface markers to aid QF of fatigue crack growth (FCG). These methods are based on load changes, including reordering the basic load histories and/or adding loads to them. The article also provides some guidelines for obtaining recognizable FCG markers for a variety of load histories and crack-growth regimes for coupons, components, and, particularly, full-scale fatigue tests.

The cast iron family includes several different groups, including gray iron, ductile iron, compacted graphite iron, malleable iron, white iron, and many different grades within each of these alloy groups. This article addresses issues specific to gray iron, but in many instances the discussion can be related to the other cast iron groups and the various grades within those groups. It discusses the usage of techniques and procedures in cast iron fractography. The article presents a list of common defects that can initiate failure.

In this article, a basic summary of fracture mechanisms in carbon and alloy steels is presented, along with numerous examples of these fractures. These examples include ductile fracture, brittle cleavage fracture, intergranular fracture, fatigue fracture, and environmentally assisted failure mechanisms.