This article focuses on the effects of mechanical plasticity on workability; that is, process control of localized stress and strain conditions to enhance workability. It describes the nature of local stress and strain states in bulk forming processes, leading to a classification scheme, including testing procedures and specific process measurements, that facilitate the application of workability concepts. Using examples, the article applies these concepts to forging, rolling, and extrusion processes. The stress and strain environments described in the article suggest that a workability test should be capable of subjecting the material to a variety of surface strain combinations. By providing insights on fracture criteria, these tests can be used as tools for troubleshooting fracture problems in existing processes, as well as in the process development for new product designs.

This article reviews quantifying adhesion, bonding, and interfacial characterization and strength in a solid-state welding process. It discusses metal-metal configurations and provides information on experimental work carried out in measuring the mechanical properties of interfaces based on theoretical analysis. A discussion on the properties affecting adhesion is also provided.

This article focuses on the factors that determine the extent of deformation a metal can withstand before cracking or fracture occurs. It informs that workability depends on the local conditions of stress, strain, strain rate, and temperature in combination with material factors. The article discusses the common testing techniques and process variables for workability prediction. It illustrates the simple and most widely used fracture criterion proposed by Cockcroft and Latham and provides a workability analysis using the fracture limit line. The article describes various workability tests, such as the tension test, ring compression test, plane-strain compression test, bend test, indentation test, and forgeability test. It concludes with information on the role of the finite-element modeling software used in workability analysis.

Solid-state welding (SSW) processes are those that produce coalescence of the faying surfaces at temperatures below the melting point of the base metal being joined without the addition of brazing or solder filler metal. This article discusses the fundamentals of welding and joining materials via the application of a nonmelting process. The specific processes usually associated with the nonmelting process are discussed.

Explosion welding (EXW), also known as explosive bonding, is accomplished by a high-velocity oblique impact between two metals. This article describes the practice of producing an explosive bond/weld and draws on many previous research results in order to explain the mechanisms involved. It provides a schematic illustration of the arrangement used in the parallel gap explosive bonding process. The article discusses several important concepts pertaining to explosive parameters, hydrodynamic flow, jetting, and metal properties. It summarizes the criteria used to model the explosive bonding process. The article describes bond morphology in terms of wave formation, bond microstructure, and bond strength determination.

This article discusses physical analysis, including slab method and upper-bound method and slip-line field analysis, for calculating stress states in plastic deformation processes. It presents various validation standards and models for evaluating the criterion of fracture for use in finite-element analyses of deformation processing. The article reviews the Cockcroft-Latham criterion of fracture and its reformulated extension for analysing the fracture locus for compression. It concludes with information on fundamental fracture models.

This article provides the definitions of stress and strain, and describes the relationship between stress and strain by stress-strain curves and true-stress/true-strain curves. The emphasis is on understanding the factors that determine the extent of deformation a metal can withstand before cracking or fracture occurs. The article reviews the process variables that influence the degree of workability and summarizes the mathematical relationships that describe the occurrence of room-temperature ductile fracture under workability conditions. It discusses the most common situations encountered in multiaxial stress states. The construction of a processing map based on deformation mechanisms is also discussed.

The fracture-mechanics technology has significantly improved the ability to design safe and reliable structures and identify and quantify the primary parameters that affect structural integrity of materials. This article provides a discussion on fracture toughness of notched materials by explaining the ductile-to-brittle fracture transition and by correlating KId, KIc, and Charpy V-notch impact energy absorptions. It highlights the effects of constraint, temperature, and loading rate on the fracture transition. The article discusses the applications of fracture mechanism in limiting of operating stresses. It describes the mechanisms, testing methods, and effecting parameters of two main categories of fracture mechanics: linear-elastic fracture mechanics and elastic-plastic fracture mechanics. The article concludes with a discussion on the three major progressive stages of fatigue: crack initiation, crack growth, and fracture on the final cycle.

This article focuses on the subject of proactive or predictive maintenance with particular emphasis on the control and prediction of corrosion damage for life extension and failure prevention. It discusses creep life assessment from the perspective of creep-rupture properties and creepcrack growth. Practical methods based on replication and parametric approaches are also discussed.

The approaches to spectrum life prediction in components can be classified into two types, namely, history-based methods, using the life-fraction rule or other damage rules, and postservice evaluation methods. This article discusses the variables affecting the material crack growth rate behavior and those essential elements in making spectrum crack growth life prediction. It provides information on life assessment for bulk creep damage.

Fracture toughness is the ability of a material to withstand fracture in the presence of cracks. This article focuses on the use of fracture toughness as a parameter for engineering and design purposes. Both linear elastic and elastic-plastic fracture mechanics concepts are reviewed as they relate to fracture toughness and design process. The article explores the use of plane strain fracture toughness, crack-tip opening displacement, and the J-integral as the criteria for the design and safe operation of structures and mechanical components. It discusses the variables affecting fracture toughness, including yield strength, loading rate, temperature, and material thickness. A summary of different fatigue and fracture mechanics design philosophies and their relationship with fracture toughness is provided. The article concludes with information on the examples of fracture toughness in design.

This article summarizes the general fatigue and fracture properties of cast steels, namely, toughness, fatigue, and component design factors such as section size and discontinuities. It describes the various factors that influence fatigue of cast steels. These factors include section size, defect size, stress modes, and waveform types. The article discusses various fracture mechanics in cast steels: cyclic stress-strain behavior and low- and high-cycle fatigue life behavior; plane-stress fracture toughness; plane-strain fracture toughness; constant-amplitude fatigue crack initiation and growth; and variable-amplitude fatigue crack initiation and growth.

This article describes the underlying fundamentals, applications, the relevance and necessity of performing proper stress analysis in conducting a failure analysis. It presents an introduction to the stress analysis of bodies containing crack-like imperfections and the topic of fracture mechanics. The fracture mechanics approach is an important part of stress analysis at the tips of sharp cracks or discontinuities. The article reviews fracture mechanics concepts, including linear elastic fracture mechanics, elastic-plastic fracture mechanics, and subcritical fracture mechanics. It also provides information on the applications of fracture mechanics in failure analysis.

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.

Flanging is a process used to form a projecting rim or edge on a part. This article explores how to determine aluminum flanging limits in terms of fracture, wrinkling, and springback, and their influencing material and process parameters with examples.

The two most important classes of materials that are manufactured via infiltration methods are copper- and silver-infiltrated refractory metals and refractory carbides, and copper-infiltrated steels. This article focuses on copper-infiltrated steels and discusses the basic requirements for infiltration, which is a technique that is only applicable to material systems that meet certain requirements. It addresses these requirements and describes the conventional (partial) infiltration process of powder metallurgy (PM) steel. The materials used in the process, such as matrix and infiltrant, are discussed. The article also details several criteria used to evaluate the performance of an infiltration process. It concludes with information on alloy steels and fully infiltrated steels.

This article focuses on direct extrusion processing where metal powders undergo plastic deformation, usually at an elevated temperature, to produce a densified and elongated form having structural integrity. It provides information on the basic powder extrusion processes and the mechanics of extrusion. The article also examines specific extrusion practices for the production of wrought material from powder stock and provides examples of materials processed by powder extrusion.

Brittle materials, such as ceramics, intermetallics, and graphites, are increasingly being used in the fabrication of lightweight components. This article focuses on the design methodologies and characterization of certain material properties. It describes the fundamental concepts and models associated with performing time-independent and time-dependent reliability analyses for brittle materials exhibiting scatter in ultimate strength. The article discusses the two-parameter and three-parameter Weibull distribution for representing the underlying probability density function for tensile strength. It reviews life prediction reliability models used for predicting the life of a component with complex geometry and loading. The article outlines reliability algorithms and presents several applications to illustrate the utilization of these reliability algorithms in structural applications.

This article discusses a set of experimental and computational studies aimed at understanding the effect of various processing parameters on the extent of burr and other defect formation during sheet edge-shearing and slitting processes. It describes the development of experimentally validated finite-element models for analyzing the classes of shearing processes. The article also discusses the use of microstructural characterization with stereology to render three-dimensional volumetric parameters. It concludes with information on the numerical simulation of an edge-shearing process, along with sensitivity studies with respect to process and tool parameters.