Stress-corrosion cracking (SCC) occurs under service conditions, which can result, often without any prior warning, in catastrophic failure. Hydrogen embrittlement is distinguished from stress-corrosion cracking generally by the interactions of the specimens with applied currents. To determine the susceptibility of alloys to SCC and hydrogen embrittlement, several types of testing are available. This article describes the constant extension testing, constant load testing, constant strain-rate testing for smooth specimens and precracked or notched specimens of SCC. It provides information on the cantilever beam test, wedge-opening load test, contoured double-cantilever beam test, three-point and four-point bend tests, rising step-load test, disk-pressure test, slow strain-rate tensile test, and potentiostatic slow strain-rate tensile test for hydrogen embrittlement.

This article describes some of the mechanical/ electrochemical phenomena related to the in vivo degradation of metals used for biomedical applications. It discusses the properties and failure of these materials as they relate to stress-corrosion cracking (SCC) and corrosion fatigue (CF). The article presents the factors related to the use of surgical implants and their deterioration in the body environment, including biomedical aspects, chemical environment, and electrochemical fundamentals needed for characterizing CF and SCC. It provides a discussion on the use of metallic biomaterials in surgical implant applications, such as orthopedic, cardiovascular surgery, and dentistry. It addresses the key issues related to simulation of the in vivo environment, service conditions, and data interpretation. Theses include frequency of dynamic loading, electrolyte chemistry, applicable loading modes, cracking mode superposition, and surface area effects. The article describes the fundamentals of CF and SCC, testing methodology, and test findings from laboratory, in vivo, and retrieval studies.

Porous coatings are used in the field of joint replacement, particularly in cementless total hip/knee arthroplasty. This article reviews the offerings and biomaterial properties in orthopedic surgery for the contemporary class of highly porous metals. It describes the traditional porous metal/coating having an open-cell structure, high porosity, and a microsctructure resembling that of cancellous bone. The traditional porous metal/coating includes fiber-metal mesh, cobalt-chromium (CoCr) beads, cancellous-structured titanium, and plasma spray. The article discusses other porous metal/coating due to the limitations of traditional porous metals for numerous open-cell-structured metals, such as titanium-base foams and trabecular metal.

High-pressure die casting is a fast method for net shape manufacturing of parts from nonferrous alloys. This article reviews the automation technologies for the different stages or steps of the process. The steps include liquid metal pouring, injection, solidification, die open, part extraction, die lubrication, insert loading, and die close. Some manual aspects of the operations together with automation options are discussed. The article describes finishing steps, such as finish trimming, detailed deflashing, shot blast cleaning, and quality checks. Automation of the postcasting process is also discussed.

This article reviews the corrosion interactions between biomedical alloys, in particular iron-base, titanium-base, and cobalt-base alloys, in complex geometries and in applications where there are significant cyclic stresses and potential for wear and fretting motion. It discusses the nature of these metal surfaces and their propensity for corrosion reactions when combined with similar or different alloys in complex restrictive environments within the human body, and under loading conditions. The article describes factors that influence mechanically assisted crevice corrosion. It reviews tests, such as scratch test and in vitro fretting corrosion test, developed to investigate the aspects of mechanically assisted corrosion of metallic biomaterials.

Titanium and its alloys have been used extensively in a wide variety of implant applications, such as artificial heart pumps, pacemaker cases, heart valve parts, and load-bearing bone or hip joint replacements or bone splints. This article discusses the properties of titanium and its alloys and presents titanium-base biomaterials in a table. Titanium components are produced in wrought, cast, and powder metallurgy (PM) form. The article describes forging, casting, and heat treating of titanium alloys for producing titanium components. Typical mechanical properties of titanium biomedical implant alloys are listed in a tabular form. The article presents an overview of surface-modification methods for titanium and its alloys implants. It concludes with a section on biocompatibility and in vivo corrosion of titanium alloys.

Honeycomb is a product consisting of very thin sheets attached to form connecting cells. This article briefly explains the construction, core characteristics, properties, and testing methods of the honeycomb structures. It discusses the special processes used to custom fit the shape of core to fit customer’s specific needs. The article provides information on sandwich structures, including material selection, design guidelines, and structural efficiency.

Traditional ceramics, one of two general classes, are commonly used in high-volume manufacturing to make building materials, household products, and various industrial goods. Although there is a tendency to equate traditional ceramics with low technology, sophisticated processes and advanced manufacturing techniques are often used where these materials are employed. This article examines several traditional ceramics, including structural clay, whiteware, glazes, enamels, portland cements, and concrete. It also provides a detailed account of fabrication methods, properties, and applications. As an example, common applications for structural clay include facing materials, load-bearing units, pavers, and ceramic tiles.

Vacuum heat treating consists of thermally treating metals and alloys in cylindrical steel chambers that have been pumped down to less than normal atmospheric pressure. This article provides a detailed account of the operations and designs of vacuum furnaces, discussing their pressure levels, resistance heating elements, quenching systems, work load support, pumping systems, and temperature control systems. It describes the classification of instruments used for measuring and recording pressure inside a vacuum processing chamber. Common devices include hydrostatic measuring devices and devices for measuring thermal and electrical conductivity. The article also describes the applications of the vacuum heat treating process, namely, vacuum nitriding and vacuum carburizing. Finally, it reviews the heat treating process of tool steels, stainless steels, Inconel 718, and titanium and its alloys.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of electronic materials, including L-shaped electronic flat pack, transistor base lead, ohmic contact window, and brush/slip ring assembly. The fractographs illustrate the atomic oxygen environment exposure effect, solar cell interconnect, integrated circuit defects, and fatigue failure of these materials.

The biocompatibility of a material relates to its immunological response, toxicity profile, and ability to integrate with surrounding tissue without undesirable local or systemic effects on a patient. This article underscores the transformation of the medical device design ecosystem engaged as an integral part of the device ecosystem. It discusses the various applications of biomaterials, including orthopedic, cardiovascular, ophthalmic, and dental applications. The article describes the four major categories of biomaterials, such as metals, polymers, glass and ceramics, and composites. A discussion on natural materials, nanomaterials, and stem cells is also provided. The article concludes with information on examples of biomaterials applications, including endovascular devices, knee implants, and neurostimulation.

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 explains the applications of continuous electroplated steel. For each category of application, the type of coating needed and the key attributes of the coating are discussed. The bulk of the article describes electrodeposition technology, including plating line components and process classification.

Electroslag remelting (ESR) is commonly used to produce the highest levels of quality in plate steels, particularly in thick plates. This article provides an overview of the ESR and discusses the major components and operations of the ESR furnaces. It describes the principles of ingot solidification and various defects of remelted ingot such as tree ring patterns, freckles, and white spots. The article explains several variations of ESR such as pressure electroslag remelting, remelting under reduced pressure, and electroslag rapid remelting. It examines the features of steel ESR and superalloy ESR.

The vacuum arc remelting (VAR) process is widely used to improve the cleanliness and refine the structure of standard air melted or vacuum induction melted (VIM) ingots and also used in the triplex production of superalloys. This article illustrates the VAR process and the capabilities and variables of the VAR process. It also presents a discussion on the melt solidification, resulting structure, and ingot defects. The article concludes with a discussion on VAR process of superalloy, and titanium and titanium alloy.

This article provides an overview of the fundamentals of tribology. It describes the advantages, disadvantages, and applications of pin-on-disk method, which is the most commonly used configuration for testing biomaterials and for the reproducible measurement of friction and wear. The article illustrates practical tribocorrosion setup that allows the user to perform wear tests in corrosive environments under well-defined electrochemical conditions and at controlled temperature. It describes the effect of changes in electrical contact resistance on tribological mode. The article discusses various in vivo environmental conditions in tribological tests. Some typical examples of biomaterials testing are also provided.

This article outlines some of the selection criteria for choosing an implant material for biomedical devices in orthopedic, dental, soft-tissue, and cardiovascular applications. It details the development of implants based on materials, such as metallic implants, ceramic implants, and polymeric implants. The article discusses the specific problems associated with implant manufacturing processes and the consequent compromises in properties of functionally graded implants. It describes the manufacturing of the functionally-graded hip implant by using the LENS process. It reviews the four different types of tissue responses to the biomaterial. The article discusses the testing of implant failure, such as in vitro and in vivo assessment of tissue compatibility.

This article addresses the biologic aspects of implant debris both locally and systemically. It discusses the particulate debris, such as stainless steel, cobalt alloy, and titanium alloy, and soluble debris obtained due to wear from all orthopedic implants. Implant debris is known to cause local inflammation, local osteolysis, and, in some cases, local and systemic hypersensitivity. The article describes debris-induced local effects, particle-induced proinflammatory responses, and debris-induced systemic effects. It concludes with a discussion on the four systemic effects of implant debris, namely, neuoropathic effects, hypersensitivity effects, carcinogenictiy, and general toxicity.

This article discusses the equipment design, procedures, experimental considerations, and interpretation of the torsion tests used to establish workability. It describes the application of torsion testing to obtain flow-stress data and to gage fracture-controlled workability and flow-localization-controlled failure. The article discusses the torsion test used to establish the processing parameters that are required to produce the desired microstructures.

The material data for forging can be divided into two categories, namely, mechanical properties and thermophysical properties. This article describes the flow characteristics of key engineering materials, such as steels, aluminum alloys, copper alloys, titanium alloys, and nickel-base superalloys. It discusses the thermophysical properties for designing or optimizing a metalworking process: specific heat, coefficient of thermal expansion, thermal conductivity/diffusivity, and density.