This article presents fractographs that show evidence of overload and fatigue in gray cast irons. The overload failure section illustrates a fractured motor housing, valve body, and bracket with microvoid coalescence (dimpled rupture) in the metal matrix between graphite flakes. The fractographs of fatigue failures illustrate a gearbox housing with fatigue striations and pearlitic microstructure.

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 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 aims to summarize the work on cryogenic strength and toughness and to present the fractography of aluminum alloys. It presents case studies on the importance of understanding the fractography of aluminum alloys and the role of microstructure in the appearance of fractographic features, with variables comprised of in-plane/through-thickness anisotropy, test temperature, heat treatment condition, and the effect of welding.

This article presents a detailed discussion on the microstructures, physical metallurgy, classification, deformation behavior, and fracture modes of titanium alloys. It illustrates the effect of microstructure and texture on the fracture topography and fracture behavior of titanium alloys with a variety of relevant examples.

Steels are among the most versatile materials in modifying their microstructure and properties by heat treatment. This article outlines the basic concepts of physical metallurgy relating to the heat treatment of steel. It considers the phases and microstructures of steel together with the transformations observed and critical temperatures during heat treatment. Additionally, the different types of steels, heat treatments, and their purposes are also discussed.

This article details investigations on the characterization of various nanofluids as quenchants for industrial heat treatment. It provides a discussion on the preparation, stability, thermophysical properties, and wetting characteristics of nanofluids. The article explains the mechanism of heat transfer in nanofluids and discusses the effect of the deposition of nanoparticles on the probe surface. The article also presents the microstructure and mechanical properties of steel quenched in nanofluids.

This article briefly introduces the concept of creep properties of additively manufactured (AM) alloys, with a focus on the effects of the characteristic microstructure of AM alloys on creep performance. Relevant postprocessing treatment also is discussed, in relation to improved creep performance based on the improvement of AM initial microstructure.

Additive manufacturing (AM) process modalities offer access to rich sets of structures for metallic materials that are otherwise difficult to obtain through a single conventional manufacturing process for bulk-scale materials. This article presents the primary aim of understanding the linkage between the process and structure in AM, which is typically focused on the correlation of machine process settings to defects such as material porosity and cracking. It also presents the development of scan strategies for site-specific microstructure control and discusses factors influencing process-structure relationships in fusion metals AM.

Additive manufacturing (AM) is a highly desired layer-by-layer fabrication process capable of creating near-net-shaped three-dimensional components for a wide range of industries, such as the automotive and aerospace industries. This article focuses on aluminum, titanium, and stainless steel alloys that are commonly used or highly desired for use with AM due to their widespread applicability and favorable mechanical properties. It presents an overview of two of the major AM processes: powder-bed and powder-fed. The article discusses processability using AM. It also provides an overview of material microstructures, defects, and the impact on mechanical behaviors.

Structure-property relationships for metal additive manufacturing (AM) using solidification-based AM processes (e.g., powder-bed fusion and directed-energy deposition) are the focus of this article. Static strength and ductility properties in AM materials are impacted heavily by the microstructure but are also affected by porosity and surface roughness. Fatigue failure in AM materials is also influenced by porosity, surface roughness, microstructure, and residual stress due to applied manufacturing processing parameters. Post-processing treatments can further influence fatigue failure in AM materials.

Process optimization is the discipline of adjusting a process to optimize a specified set of parameters without violating engineering constraints. This article reviews data-driven optimization methods based on genetic algorithms and stochastic models and demonstrates their use in powder-bed fusion and directed energy deposition processes. In the latter case, closed-loop feedback is used to control melt pool temperature and cooling rate in order to achieve desired microstructure.

This article focuses specifically on material modeling applied to structure-property predictions. It provides general guidelines and considerations in terms of modeling the salient material features that ultimately impact the mechanical performance of parts produced by additive manufacturing (AM). Two of the primary ingredients needed to predict structure-property relationships via material modeling include a geometrical representation of the microstructural features of interest (e.g., grain structure and void defects) and a suitable constitutive model describing the material behavior, both of which can be scale and resource dependent. The article also presents modeling challenges to predict various aspects of (process-) structure-property relationships in AM.

This article provides an overview of different modeling approaches used to capture the phenomena present in the additive manufacturing (AM) process. Inherent to the thermomechanical processing that occurs in AM for metals is the development of residual stresses and distortions. The article then provides an overview of thermal modeling. It presents a discussion on solid mechanics simulation and microstructure simulation.

X-ray radiography and computed tomography (CT) are nondestructive testing (NDT) tools particularly well suited to additive manufacturing (AM). A brief overview of NDT for AM is presented in this article, including other NDT methods, followed by identifying the key advantages and requirements for x-ray radiography and CT in AM. Less widely known applications of CT are also presented, including powder characterization, the evaluation of lattice structures, surface roughness measurements, and four-dimensional CT involving interrupted (before-after) CT scans of the same parts, or even in situ scans of the same part subjected to some processing or loading conditions. The article concludes with a discussion on the limits and some guidelines for the use of x-ray and CT for various AM materials.

The first part of this article focuses on two major forms of machining-related failures, namely machining workpiece (in-process) failures and machined part (in-service) failures. Discussion centers on machining conditions and metallurgical factors contributing to (in-process) workpiece failures, and undesired surface layers and metallurgical factors contributing to (in-service) machined part failures. The second part of the article discusses the effects of microstructure on machining failures and their preventive measures.

Directed-energy deposition (DED) is a kind of additive manufacturing (AM) technology based on synchronous powder feeding or wire feeding. This article provides a comprehensive coverage of DED for ceramic AM, beginning with an overview of DED equipment setup, followed by a discussion on DED materials and the DED deposition process. The bulk of the article is devoted to the discussion on the microstructure and properties of oxide ceramics, namely alumina and zirconia ceramics.