This article presents fractographs of overload fractures in a ductile cast iron piston, tensile test bar, differential case, brake caliper, compressor crankshaft, and pivot arm. SEM images show such features as dimpled rupture at the thin metallic matrix ligatures between the graphite nodules, bull's-eye ferrite and pearlite microstructure, loose graphite nodules and dimpled rupture morphology transitioning to cleavage, cleavage morphology with river lines, and ratchet marks and beach marks.

This article presents fractographs that show evidence of overload in white cast irons. Images illustrate brittle fracture with cleavage facets and fracture at carbide boundaries, as well as cracks caused by shear stress and the tensile stress due to rebounding.

This article presents fractographs that show evidence of overload in a ferritic malleable cast iron. The images illustrate crack initiation and propagation, as well as regions of dimpled rupture.

This article presents fractographs of pure irons that show evidence of overload, fatigue, and embrittlement. Woody fracture, microvoid coalescence, cleavage, and stress rupture are seen in the overload failure images. A large inclusion is seen in the fatigue fractograph. Embrittlement images show an impact fracture with intergranular rupture and transcrystalline cleavage.

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.

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.

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 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 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.

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.

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.

Fracture of aluminum alloys can occur due to several failure types and/or fracture morphologies, including overload, intergranular fracture, fatigue, corrosion, and mixed-mode fracture. This article provides a detailed discussion on these failure types and/or fracture morphologies. It also presents the differences between wrought and cast aluminum products.