Understanding fatigue crack growth is critical for the safe operation of many structural components. This article reviews the standard fracture mechanics and methods to determine the crack growth rate for a material and loading condition experimentally. It also addresses the two most important aspects of crack-growth modeling: loading environment and crack geometry.

This article describes eight stages of the atomistic film growth: vaporization of the material, transport of the material to the substrate, condensation and nucleation of the atoms, nuclei growth, interface formation, film growth, changes in structure during the deposition, and postdeposition changes. It also discusses the effects and causes of growth-related properties of films deposited by physical vapor deposition processes, including residual film stress, density, and adhesion.

Engineered components fail predominantly in four major ways: fracture, corrosion, wear, and undesirable deformation (i.e., distortion). Typical fracture mechanisms feature rapid crack growth by ductile or brittle cracking; more progressive (subcritical) forms involve crack growth by fatigue, creep, or environmentally-assisted cracking. Corrosion and wear are another form of progressive material alteration or removal that can lead to failure or obsolescence. This article primarily covers the topic of abrasive wear failures, covering the general classification of wear. It also discusses methods that may apply to any form of wear mechanism, because it is important to identify all mechanisms or combinations of wear mechanisms during failure analysis. The article concludes by presenting several examples of abrasive wear.

Any model that describes the early stage of cavitation must therefore address experimental observations of continuous nucleation, cracklike interface cavities, cavity growth from nanometer-scale sizes, and debonding at particle interfaces and formation of large-faceted cavities. This article summarizes the microstructural details of the early stages of cavitation in metals for understanding the interface-constrained plasticity cavitation model. It discusses formulation, predictions and implications, involved in analysis of cavitation under constrained conditions.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of AISI/SAE alloy steels (4xxx steels) and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the brittle fracture, ductile fracture, impact fracture, fatigue fracture surface, reversed torsional fatigue fracture, transgranular cleavage fracture, rotating bending fatigue, tension-overload fracture, torsion-overload fracture, slip band crack, crack growth and crack initiation, crack nucleation, microstructure, hydrogen embrittlement, sulfide stress-corrosion failure, stress-corrosion cracking, and hitch post shaft failure of these steels. The components considered in the article include tail-rotor drive-pinion shafts, pinion gears, outboard-motor crankshafts, bull gears, diesel engine bearing cap bolts, splined shafts, aircraft horizontal tail-actuator shafts, bucket elevators, aircraft propellers, helicopter bolts, air flasks, tie rod ball studs, and spiral gears.

This article briefly reviews the factors that influence the occurrence of intergranular (IG) fractures. Because the appearance of IG fractures is often very similar, the principal focus is placed on the various metallurgical or environmental factors that cause grain boundaries to become the preferred path of crack growth. The article describes in more detail some typical mechanisms that cause IG fracture. It discusses the causes and effects of IG brittle cracking, dimpled IG fracture, IG fatigue, hydrogen embrittlement, and IG stress-corrosion cracking. The article presents a case history on IG fracture of steam generator tubes, where a lowering of the operating temperature was proposed to reduce failures.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of polymers, including polycarbonate, polyethylene, and polyimide, and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the quasi-brittle fatigue crack propagation, brittle and ductile fracture, crack-growth mechanisms, tearing, fibrillation, and fatigue striations of these surfaces.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of titanium alloys and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the fracture surface, fatigue crack growth, intergranular fracture, crack propagation, ductile overload fracture, dimpled rupture, microvoid coalescence, and quasi-cleavage fracture of these alloys.

This article describes concepts and tools that can be used by the failure analyst to understand and address deformation, cracking, or fracture after a stress-related failure has occurred. Issues related to the determination and use of stress are detailed. Stress is defined, and a procedure to deal with stress by determining maximum values through stress transformation is described. The article provides the stress analysis equations of typical component geometries and discusses some of the implications of the stress analysis relative to failure in components. It focuses on linear elastic fracture mechanics analysis, with some mention of elastic-plastic fracture mechanics analysis. The article describes the probabilistic aspects of fatigue and fracture. Information on crack-growth simulation of the material is also provided.

This article reviews the various types of mechanical testing methods, including hardness testing; tension testing; compression testing; dynamic fracture testing; fracture toughness testing; fatigue life testing; fatigue crack growth testing; and creep, stress-rupture, and stress-relaxation testing. Shear testing, torsion testing, and formability testing are also discussed. The discussion of tension testing includes information about stress-strain curves and the properties described by them.

This article describes the vapor-phase growth techniques applied to the epitaxial deposition of semiconductor films and discusses the fundamental processes involved in metal-organic chemical vapor deposition (MOCVD). It reviews the thermodynamics that determine the driving force behind the overall growth process and the kinetics that define the rates at which the various processes occur. The article provides information on the reactor systems and hardware, MOCVD starting materials, engineering considerations that optimize growth, and the growth parameters for a variety of Group III-V, II-VI, and IV semiconductors.

Sintering provides the interparticle bonding that generates the attractive forces needed to hold together the otherwise loose ceramic powder mass. It also improves hardness, strength, transparency, toughness, electrical conductivity, thermal expansion, magnetic saturation, corrosion resistance, and other properties. This article discusses the fundamentals of sintering and its effects on pore structures and particle density. It addresses some of the more common sintering methods, including solid-state, liquid-phase, and gas pressure sintering, and presents alternative processes such as reaction sintering and self-propagating, high-temperature synthesis. It also describes several pressure densification methods, including hot isostatic pressing, gas pressure sintering, molten particle deposition, and sol-gel processing. The article concludes with a section on grain growth that discusses the underlying mechanisms and kinetics and the relationship between grain growth and densification.

This article discusses the fundamental aspects of phase-field microstructure modeling. It describes the evolution of microstructure modeling, including nucleation, growth, and coarsening. The article reviews two approaches used in the modeling nucleation of microstructure: the Langevin force approach and explicit nucleation algorithm. Calculation of activation energy and critical nucleus configuration is discussed. The article presents the deterministic phase-field kinetic equations for modeling growth and coarsening of microstructure. It also describes the material-specific model inputs, chemical free energy and kinetic coefficients, for phase-field microstructure modeling. The article provides four examples that illustrate some aspects of phase-field modeling.

Stress-corrosion cracking (SCC) is a form of corrosion and produces wastage in that the stress-corrosion cracks penetrate the cross-sectional thickness of a component over time and deteriorate its mechanical strength. Although there are factors common among the different forms of environmentally induced cracking, this article deals only with SCC of metallic components. It begins by presenting terminology and background of SCC. Then, the general characteristics of SCC and the development of conditions for SCC as well as the stages of SCC are covered. The article provides a brief overview of proposed SCC propagation mechanisms. It discusses the processes involved in diagnosing SCC and the prevention and mitigation of SCC. Several engineering alloys are discussed with respect to their susceptibility to SCC. This includes a description of some of the environmental and metallurgical conditions commonly associated with the development of SCC, although not all, and numerous case studies.

The purposes and methods of fatigue modeling and simulation in high-cycle fatigue (HCF) regime are to design either failsafe components or components with a finite life and to quantify remaining life of components with pre-existing cracks using fracture mechanics, with the intent of monitoring via an inspection scheme. This article begins with a discussion on the stages of the fatigue damage process. It describes hierarchical multistage fatigue modeling and several key points regarding the physics of crack nucleation and microstructurally small crack propagation in the HCF regime. The article provides a description of the microstructure-sensitive modeling to model fatigue of several classes of advanced engineering alloys. It describes the various modeling and design processes designed against fatigue crack initiation. The article concludes with a discussion on the challenges in microstructure-sensitive fatigue modeling.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of austenitic stainless steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the following: fatigue-crack fracture, rock candy fracture, cleavage fracture, brittle fracture, high-cycle fatigue fracture, fatigue striations, hydrogen-embrittlement failure, creep crack propagation, fatigue crack nucleation, intergranular creep fracture, torsional overload fracture, stress-corrosion cracking, and grain-boundary damage of these steels. The austenitic stainless steel components include spring wires, preheater-reactor slurry transfer lines and gas lines of coal-liquefaction pilot plants, oil feed tubes and suction couch rolls of paper machines, cortical screws and compression hip screws of orthopedic implants, and Jewett nails.

Analysis of bifilms provides a simple, powerful, and elegant concept to explain many features of the metallurgy of castings. This article describes the effects of bifilms in metals. Mechanisms for the entrainment of bifilms are reviewed. The article describes the effect of furling and unfurling on mechanical properties of the solidified cast metal. It provides a discussion on the mechanisms of unfurling to determine the casting properties of the metals. These include gas precipitation, shrinkage, linear contraction, dendrite pushing, and nucleation and growth of intermetallics. The article also describes the role of bifilm defects in fracture.

This article describes the heat treatment of wrought solid-solution and precipitation-hardening alloys with a focus on the major families of wrought nickel alloys. It also provides information on the heat treatment of some representative solid-solution alloys in the Monel (Ni-Cu), Inconel (Ni-Cr-Mo), Hastelloy (Ni-Mo-Cr), and Incoloy (Ni-Fe-Cr) families of alloys. The heat treatment processes for gamma prime nickel alloys, gamma prime nickel-iron superalloys, and gamma double-prime nickel-iron superalloys are also included. The article also provides information on age-hardenable alloys, and the effects of cold work on aging response and grain growth with examples.

Brasses are copper alloys with zinc as the principal alloying element. This article provides information on the chemical compositions and mechanical properties of the three types of brasses: alpha, duplex and beta. It briefly discusses the Unified Numbering System designations, compositions, and classifications of wrought brasses and cast brasses. The article provides a discussion on annealing, recrystallization, and grain growth of wrought brasses. Stress relief of wrought brasses, which is typically conducted below the annealing temperatures, is also briefly described.

This article assesses the evolution of martensite modeling in the changing materials engineering environment. It describes the physics of displacive transformations using Ginzburg-Landau theory, microstructure representation, dynamics and simulations, density functional theory, and shuffle transitions. The article reviews the application of the Ginzburg-Landau approach to rigorous solutions for issues in the structure of a martensitic nucleus based on the martensitic nucleation theory. The three basic behavior modes of martensitic growth, such as elastic, elastic/plastic, and fully plastic are discussed. The article also reviews the overall kinetics of martensitic transformations.