This article begins with a description of indirect and direct semisolid metalworking processes. It then provides information on alloy compositions of common aluminum semisolid metalworking alloys and primary die-cast magnesium alloys in a tabular form. The article describes the macroscopic examination of defects, which occur in semisolid metalworking with illustrations. It discusses the macroscopic examination of gating systems and semisolid feedstocks. The article also provides information on feedstock microstructures, direct semisolid metalworking component microstructures, and indirect semisolid metalworking component microstructures of series 300 aluminum casting alloys and magnesium die-casting alloys.

Examination of a damaged component involves a chain of activities that, first and foremost, requires good observation and documentation. Following receipt and documentation, the features of damage can be recorded and their cause(s) investigated, as this article briefly describes, for typical types of damage experienced for metallic components. This article discusses the processes involved in visual or macroscopic examination of damaged material; the interpretation of fracture features, corrosion, and wear damage features; and the analysis of base material composition. It covers the processes involved in the selection of metallurgical samples, the preparation and examination of metallographic specimens in failure analysis, and the analysis and interpretation of microstructures. Examination and evaluation of polymers and ceramic materials in failure analysis are also briefly discussed.

This article commences with a discussion on the characteristics of stress-corrosion cracking (SCC) and describes crack initiation and propagation during SCC. It reviews the various mechanisms of SCC and addresses electrochemical and stress-sorption theories. The article explains the SCC, which occurs due to welding, metalworking process, and stress concentration, including options for investigation and corrective measures. It describes the sources of stresses in service and the effect of composition and metal structure on the susceptibility of SCC. The article provides information on specific ions and substances, service environments, and preservice environments responsible for SCC. It details the analysis of SCC failures, which include on-site examination, sampling, observation of fracture surface characteristics, macroscopic examination, microscopic examination, chemical analysis, metallographic analysis, and simulated-service tests. It provides case studies for the analysis of SCC service failures and their occurrence in steels, stainless steels, and commercial alloys of aluminum, copper, magnesium, and titanium.

This article describes the metallographic technique for nonferrous metals and special-purpose alloys. These include aluminum alloys, copper and copper alloys, lead and lead alloys, magnesium alloys, nickel and nickel alloys, magnetic alloys, tin and tin alloys, titanium and titanium alloys, refractory metals and alloys, zinc and zinc alloys, and wrought heat-resisting alloys. The preparation of specimens for metallographic technique includes operations such as sectioning, mounting, grinding, polishing, and etching of nonferrous metals and alloys. The article contains tables that list the etchants for macroscopic examination and microscopic examination of nonferrous metals and special-purpose alloys.

This article focuses on the visual or macroscopic examination of damaged materials and interpretation of damage and fracture features. Analytical tools available for evaluations of corrosion and wear damage features include energy dispersive spectroscopy, electron probe microanalysis, Auger electron spectroscopy, secondary ion mass spectroscopy, and X-ray powder diffraction. The article discusses the analysis and interpretation of base material composition and microstructures. Preparation and examination of metallographic specimens in failure analysis are also discussed. The article concludes with a review of the evaluation of polymers and ceramic materials in failure analysis.

This article describes various evaluation techniques of fractography such as visual inspection, macroscopic and microscopic examinations that are used to resolve different aspects of failure. It gives a brief description and pictorial representation of various defects leading to fracture of metals, including laps, seams, cold shuts, cracks, inclusions, porosity, fatigue, and stress corrosion cracking.

This article presents examples of the visual fracture examination that illustrate the procedure as it applies to failure analysis and quality determination. It describes the techniques and procedures for the visual and light microscopic examination of fracture surfaces with illustrations. The article also describes microscopic and macroscopic features of the different fracture mechanisms with illustrations with emphasis on visual and light microscopy examination. The types of fractures considered include ductile fractures, tensile-test fractures, brittle fractures, fatigue fractures, and high-temperature fractures.

The metallographic specimen preparation process for microstructural investigations of cast iron specimens usually consists of five stages: sampling, cold or hot mounting, grinding, polishing, and etching with a suitable etchant to reveal the microstructure. This article describes the general preparation of metallographic specimens and the methods of macroscopic and microscopic examination. Usually, gray-scale (black-and-white) metallography is sufficient for microstructural analysis of cast irons. The article discusses the use of color metallography of gray irons and ductile irons. It also presents application examples of color metallography.

This article describes metallographic preparation and examination techniques for stainless steels and maraging steels. It presents a series of micrographs demonstrating microstructural features of these alloys. Procedures used to prepare stainless steels for macroscopic and microscopic examination are similar to those used for carbon, alloy, and tool steels. Cutting and grinding must be carefully executed to minimize deformation because the austenitic grades work harden readily. The high-hardness martensitic grades that contain substantial undissolved chromium carbide are difficult to polish while fully retaining the carbides. Unlike carbon, alloy, and tool steels, etching techniques are more difficult due to the high corrosion resistance of stainless steels and the various second phases that may be encountered. The microstructures of stainless steels can be quite complex. Matrix structures vary according to the type of steel, such as ferritic, austenitic, martensitic, precipitation hardenable, or duplex.

Optical metallography, one of the most common materials characterization techniques, uses visible light to magnify structural features of interest. This article discusses the use of optical methods to evaluate micro and macrostructure and relate it to process conditions and material behavior. It covers the steps involved in sample preparation, including sectioning, mounting, grinding, polishing, and etching, and presents several examples of macro and microanalysis on various metals and alloys.

This article outlines the basic steps to be followed and the range of techniques available for failure analysis, namely, background data assembling, visual examination, microfractography, chemical analysis, metallographic examination, electron microscopy, electron microprobe analysis, X-ray techniques, and simulations. It also describes the steps for analyzing the data, preparing the report, preservation of evidence, and follow-up on recommendations.

This article explains how to prepare nickel-base alloys for metallographic examination and identifies related processing and imaging challenges. It describes sectioning, mounting, grinding, and polishing procedures along with alternative electropolishing processes. It also provides information on etching and examines the microstructure of Nickel 200, Nickel 270, Duranickel 301, Monel 400, Monel R-405, Monel K-500, and other nickel alloys.

The presence of macroscopic residual stresses in heat treatable aluminum alloys can give rise to machining distortion, dimensional instability, and increased susceptibility to in-service fatigue and stress-corrosion cracking. This article details the residual-stress magnitudes and distributions introduced into aluminum alloys by thermal operations associated with heat treatment. The available technologies by which residual stresses in aluminum alloys can be relieved are also described. The article shows why thermal stress relief is not a feasible stress-reduction technology for precipitation-hardened alloys. It examines the consequences of aging treatments on the residual stress, namely, annealing, precipitation heat treatment, and cryogenic treatment. The article provides information on uphill quenching, which attempts to reverse thermal gradients encountered during quenching. It examines how quench-induced residual stresses in heat treatable aluminum alloys are reduced when sufficient load is applied to cause plastic deformation. The article also shows how plastic deformation reduces residual stress.

This article commences with a summary of fatigue processes and mechanisms. It focuses on fractography of fatigue. Characteristic fatigue fracture features that can be discerned visually or under low magnification are described. Typical microscopic features observed on structural metals are presented subsequently, followed by a brief discussion of fatigue in nonmetals. The article reviews the various macroscopic and microscopic features to characterize the history and growth rate of fatigue in metals. It concludes with a description of fatigue of polymers and composites.

This article provides an overview of the origin of metallography. It presents information on how to select a section from a specimen and prepare it for macroscopic analysis. The article describes the macroscopic analysis of steel fracture surfaces with emphasis on ductile, brittle, and fatigue fracture with illustrations. It discusses microanalysis with a focus on the method of light microscopy and includes information of scanning electron microscope in fractography. The article also explains the characteristics of solidification, transformation, deformation structures, and discontinuities that are present in a microstructure. It concludes with information on image analysis.

Fatigue failure of engineering components and structures results from progressive fracture caused by cyclic or fluctuating loads. Fatigue is an important potential cause of mechanical failure, because most engineering components or structures are or can be subjected to cyclic loads during their lifetime. This article focuses on fractography of fatigue. It provides an abbreviated summary of fatigue processes and mechanisms: fatigue crack initiation, fatigue crack propagation, and final fracture,. Characteristic fatigue fracture features that can be discerned visually or under low magnification are then described. Typical microscopic features observed on structural metals are presented subsequently, followed by a brief discussion on fatigue in polymers and polymer-matrix composites.

This article describes the preliminary stages and general procedures, techniques, and precautions employed in the investigation and analysis of metallurgical failures that occur in service. The most common causes of failure characteristics are described for fracture, corrosion, and wear failures. The article provides information on the synthesis and interpretation of results from the investigation. Finally, it presents key guidelines for conducting a failure analysis.

This article reviews the failure analysis process with specific reference to the considerations that should be addressed when a casting has failed. It describes the failure analysis methodology for three failed cast components: an aluminum bracket, a bronze suction roll, and a steel automotive spindle. The article discusses failure analysis investigation by obtaining casting background information, planning the evaluation and selecting the appropriate casting for analysis, conducting a preliminary examination, conducting the proper material evaluations, and thoroughly evaluating the test data. It concludes with information on case studies that show how the methodology is adapted for differing materials, failure mechanisms, and failure circumstances.

As cast iron parts are extensively applied, fracture events will eventually take place. Consequently, it becomes essential to carry out failure analyses to identify the cause of fracture and to provide corrective actions that allow safe operation. This article presents a description of the main fracture modes and their characteristic fractographic features. It discusses the four principal fracture modes: dimple rupture (or fracture), cleavage, fatigue, and intergranular fracture. The article provides information on special cases of environmentally assisted fracture. It concludes with a description of fractographic analyses for identifying the direction of propagation of a crack.

This article describes the microstructure of copper alloys, including copper-zinc (brasses), bronzes, copper-nickel, and copper-nickel-zinc, and examines the effect of oxygen content on alloy phases observed in different product forms. The article also discusses inclusions, etchants, and the effect of composition and processing on grain structure and growth rates.