bluuebunny/crossref_metadata_2025 huggingface dataset:
Secondary Operations for Powder Metallurgy Stainless Steels
Authors: dePoutiloff Peter A
Published: December 2018

Powder metallurgy (PM) stainless steels, as with conventional PM steels, are often used in the as-sintered condition. In addition to cost considerations, minimization of postsinter handling and secondary operations is also preferred because it reduces the potential for contamination of the parts with particulates and residues, which can result in the appearance of surface rust. This article provides information on various secondary operations, including tumbling, re-pressing, resin impregnation, annealing or heat treating, brazing, machining, and welding. It describes those aspects relating to welding of PM stainless steels, specifically, the effects of density, residual porosity, and sintered chemistry on weldability. Further, the article investigates the influence the sintering atmosphere has on machinability, as well as differences created by the presence of residual porosity.
Properties of Powder Metallurgy Tool Steels
Authors: Beiss Paul
Published: December 2018

Powder metallurgy (PM) high-alloy tool steels (HATS) have unique properties that assist them in solving various problems related to machining of metal components. This article describes the cost-intensive PM processing routes of HATS, as well as their major properties, including elastic properties, density, mechanical properties, grindability, fatigue and wear resistance, and thermophysical properties.
Effects of Alloying on Powder Metallurgy Tool Steels
Authors: Beiss Paul
Published: December 2018

This article describes the effects of undissolved carbides formed by segregation of alloying elements on the hardness of the powder-metallurgical (PM) high-alloy tool steels (HATS). It explains the calculation of exact stoichiometric carbon content that depends on the required martensite hardness, amount of carbon forming alloying elements, types of undissolved carbides during austenitizing, and the densities of the carbides. Microhardness values for carbides in HATS are also listed.
Direct Powder Rolling
Authors: Samal Prasan K.
Published: December 2018

Direct powder rolling (DPR) is a process by which a suitable powder or mixture of powders is compacted under the opposing forces of a pair of rolling mill rolls to form a continuous green strip that is further densified and strengthened by sintering and rerolling. This article discusses the basic principle, process considerations, and advantages of DRP, and describes the application of this process in the manufacture of powder titanium and titanium alloy components. It further illustrates the complexity of the process and describes the benefits of using DRP in terms of economics and product quality.
Interdiffusion Structures
Authors: Morral J.E. , Dayananda M.A.
Published: December 2018

Interdiffusion microstructures appear as a region on either side of the original interface of contact between two materials. This article outlines the principles used in analyzing various interdiffusion microstructures: binary systems, copper-base systems, nickel-base systems, and silicide-forming systems. The analysis can be helpful in classifying microstructures and in understanding how they change with alloy composition, especially when thermal history is known. The microstructures also help in identifying microstructural artifacts caused by polishing and in recognizing errors in reported heat treating schedules.
Field Metallography Techniques
Authors: Bramfitt Bruce L. , Lawrence Samuel J.
Published: December 2018

This article discusses the advantages and disadvantages of field metallography and describes the important material characteristics and other aspects to be considered before performing any metallographic procedure. It investigates the various stages of sample preparation in the metallographic laboratory: grinding, polishing, etching, preparing a replica, and obtaining a small sample. The article also illustrates the applications of field metallography with case studies.
Metallography and Microstructures of Stainless Steels and Maraging Steels
Authors: Vander Voort George F. , Lucas Gabriel M. , Manilova Elena P.
Published: December 2018

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.
Metallography and Microstructures of Beryllium, Copper-Beryllium, and Nickel-Beryllium Alloys
Authors: Harkness John C. , Guha Amitava
Published: December 2018

The two major types of beryllium-containing alloys are copper-berylliums and nickel-berylliums. The most widely used beryllium-containing alloys are wrought copper-berylliums, which provide good strength while retaining useful levels of electrical and thermal conductivity. This article provides information on the specimen preparation procedures, macroexamination, microexamination, and microstructures of beryllium, copper-beryllium alloys, as well as nickel-beryllium alloys. It also discusses health and safety measures associated with the specimen preparation of beryllium and beryllium-containing alloys.
Metallography and Microstructures of Magnesium and Its Alloys
Authors: Padfield Toby V.
Published: December 2018

Magnesium and its alloys are among the most difficult metals to prepare for metallographic examination. This article describes specimen preparation processes, including sectioning, mounting, grinding, and polishing. It discusses macro and microexamination techniques as well as related etching processes, including macroetching and color etching based on polarized light enhancement. The article concludes with an overview of the effects of alloying elements, including aluminum, beryllium, calcium, copper, iron, lithium, manganese, rare earth metals, silicon, silver, strontium, thorium, tin, zinc, and zirconium.
Preparation and Microstructural Analysis of High-Performance Ceramics
Authors: Täffner Ulrike , Carle Veronika , Schäfer Ute , Hoffmann Michael J.
Published: December 2018

Microstructural analysis reveals many important details about the qualities and capabilities of high-performance ceramics. This article explains how to prepare ceramic samples for imaging and the imaging technologies normally used. It describes sectioning, mounting, grinding, and polishing as well as ceramographic etching. It discusses common imaging approaches, including scanning electron microscopy and thin-section polarized light techniques, a type of optical microscopy. The article also addresses microstructural classification, examining detailed micrographs from samples of aluminum oxide, zirconium dioxide, aluminum nitride, silicon carbide, and piezoelectric ceramics.
Introduction—Composite Materials and Optical Microscopy
Authors: Hayes Brian S. , Gammon Luther M.
Published: December 2018

This article illustrates the polymer matrices used for composite materials. It describes the use of prepeg materials in manufacturing high-performance composites. The article discusses the various infusion processes for the development of fiber-reinforced composites, namely, resin transfer molding, vacuum-assisted resin transfer molding, and resin film infusion. It explains the composite- and matrix-toughening methods for fiber-reinforced composites, such as dispersed-phase toughening and interlayer toughening. The article concludes with information on optical microscopy, which provides an insight into the micro- and macrostructure of fiber-reinforced composites.
Viewing Composite Specimens Using Reflected Light Microscopy
Authors: Hayes Brian S. , Gammon Luther M.
Published: December 2018

The analysis of composite materials using optical microscopy is a process that can be made easy and efficient with only a few contrast methods and preparation techniques. This article is intended to provide information that will help an investigator select the appropriate microscopy technique for the specific analysis objectives with a given composite material. The article opens with a discussion of macrophotography and microscope alignment, and then goes on to describe various illumination techniques that are useful for specific analysis requirements. These techniques include bright-field illumination, dark-field illumination, polarized-light microscopy, interference and contrast microscopy, and fluorescence microscopy. The article also provides a discussion of sample preparation materials such as dyes, etchants, and stains for the analysis of composite materials using optical microscopy.
Thin Section Preparation and Transmitted Light Microscopy for Fiber-Reinforced Composites
Authors: Hayes Brian S. , Gammon Luther M.
Published: December 2018

This article describes the various aspects relating to the selection and preparation of ultrathin-section specimens of fiber-reinforced polymeric composites for examination by transmitted light microscopy. It provides information on the contrast-enhancement methods used by transmitted-light microscopy and optimization of microscope conditions. Examples of composite ultrathin sections analyzed using transmitted-light microscopy contrast methods are also presented.
Design for Deformation Processing
Authors: Kuhn Howard
Published: December 2018

This article reviews the general aspects of product design and provides an overview of the manufacturing processes and their relationship to design, with an emphasis on deformation processes. It discusses the various classes of deformation processes to illustrate their impacts on product design while taking advantage of the benefits of deformation processing.
Precision Hot Forging
Authors: Richard Douglas J.
Published: December 2018

Precision forging is defined as a closed-die forging process in which the accuracy of the shape, dimensional tolerances, and surface finish exceed normal expectations to the extent that some of the postforge operations can be eliminated. This article provides an overview of the key factors that impact the precision forging process. It provides information on the achievable tolerances and presents examples of precision forging. A discussion on forging of bevel gears/spiral bevel gears is also presented.
Forging of Carbon and Alloy Steels
Authors: Van Tyne C.J.
Published: December 2018

This article focuses on the forging behavior and practices of carbon and alloy steels. It presents general guidelines for forging in terms of practices, steel selection, forgeability and mechanical properties, heat treatments of steel forgings, die design features, and machining. The article discusses the effect of forging on final component properties and presents special considerations for the design of hot upset forgings.
Thermomechanical Processes for Nonferrous Alloys
Authors: Furrer D.U. , Semiatin S.L.
Published: December 2018

The thermomechanical processing (TMP) of conventional and advanced nickel and titanium-base alloys is aimed at altering or enhancing one or more metallurgical features within the material and component. This article presents a number of examples of the TMP of nickel-base superalloys and titanium alloys. The TMP techniques include retained-strain processing, dual-microstructure processing, and dual-alloy processing. The article also describes the TMP of alpha-beta titanium alloys, including fine-grain processing, hybrid-structure processing, dual-microstructure processing, and dual-alloy processing. It concludes with a discussion on computer simulation of advanced TMP processes.
Roll Forming of Axially Symmetric Components
Authors: Bewlay B.P. , Gigliotti M.F.X. , Hardwick C.U. , Kaibyshev O.A. , Valitov V.A. , Furrer D.U.
Published: December 2018

This article describes the roll forming of components of nickel, titanium, and aluminum alloys. The metallurgical characteristics of the roll formed components, such as macrostructures, microstructures, tensile strength, and stress rupture performance, are discussed. The article compares the resulting properties of roll formed and conventionally forged components.
Models for Predicting Microstructural Evolution
Authors: Beynon J.H. , Sellars C.M.
Published: December 2018

The systematic study of microstructural evolution during deformation under hot working conditions is important in controlling processing variables to achieve dimensional accuracy. This article explains the microstructural features that need to be modeled and provides an outline of the principles and achievements of each of the various microstructural models, including black-box modeling, gray-box modeling, white-box modeling, and hybrid modeling.
Workability and Process Design in Extrusion and Wire Drawing
Authors: Wright Roger N.
Published: December 2018

Workability is the ability of the workpiece metal to undergo extrusion or drawing without fracture or defect development. This article describes the limits of workability in extrusion and drawing in terms of fracture and flaw development and presents some comments on fracture mechanisms. It discusses the empirical projections of absolute workability from various mechanical tests. The article concludes with a discussion on extrusion and drawing process design implications.
Age Forming
Authors: Kallivayalil Jacob A.
Published: December 2018

Compared to cold-formed parts, age-formed parts have lower residual stresses and consequently better stress corrosion resistance. This article addresses the technical issues that arise in the investigations of creep in precipitate-strengthened materials. The issues addressed help in developing alloys and tempers particularly suited for the age-forming process. The different steps involved in the program for predicting the final part shape are discussed. These basic steps involve developing mechanical tests to study creep at low temperatures and low stresses, describing low-temperature creep in terms of a constitutive model, and then using the constitutive model in a process model or finite element analysis to predict the final part shape.
Forming of Wire
Authors: Berardis David
Published: December 2018

This article describes the operation procedures of wire rolling in a Turks Head machine. It discusses spring coiling, as well as the manual and power bending used in the wire forming process. The article contains a table that lists examples of several wire-forming production problems and solutions. Lubricants for wire forming such as inorganic fillers, soluble oils, and boundary lubricants are reviewed. The article also analyzes the applications of lubricants in wire forming.
Forming of Copper and Copper Alloys
Authors: Mandigo Frank , Tyler Derek
Published: December 2018

This article reviews the general characteristics of copper and copper alloys and explains how these characteristics affect the behavior of strip in different types of forming operations. These forming operations include blanking, piercing, bending, drawing and stretch forming, spinning, rubber-pad forming, and contour roll forming. Specialized forming operations such as hydraulic forming, embossing and swaging, and high-velocity metal forming are also reviewed. The article discusses the forming of smaller and larger parts from copper and copper alloy strips, as well as their property requirements and applications.
Formability Testing of Sheet Metals
Authors: Miles Michael
Published: December 2018

Sheet metal forming operations are so diverse in type, extent, and rate that no single test provides an accurate indication of the formability of a material in all situations. This article presents an overview of types of forming, formability problems, and principal methods of measuring deformation. It reviews the effect of materials properties and temperature on formability. The article provides a detailed discussion on the two major categories of formability tests such as the intrinsic test, including uniaxial tension testing, plane-strain tension testing, biaxial stretch testing, and simulative tests such as bending tests, stretching tests, the Ohio State University test, the drawing test, and stretch-drawing tests. It extends the correlation between simulative tests and materials properties using forming limit diagrams and circle grid analysis, and discusses the improvements to the forming limit diagram technology.
CAD/CAM and Die Face Design in Sheet Metal Forming
Authors: Herman Ed , Schaeffler Daniel J. , Vineberg Evan J.
Published: December 2018

This article describes grade designations of the various sheet steels used for draw forming. It discusses the specifications associated with most sheet draw forming materials. The article examines the behavior of stress- and strain-based forming limit curve (FLC). It provides a discussion on three separate frictional conditions acting in a draw die. The frictional conditions include the metal passing through a draw bead, the metal clamped in the binder, and the metal sliding across a die radius. The article also explains the basic steps in the vehicle development process. The steps involved in the thought process of direct engineering for formability are also explained. The article places considerable emphasis on the need for the designer to clearly define the die/tooling faces in the computer-aided design (CAD)/computer-aided manufacturing (CAM) system before the data are passed on to the construction functions.
Forming of Refractory Metals
Authors: Huber Louis E. , Michaluk Christopher A.
Published: December 2018

This article describes the formability and surface contamination of the refractory metals such as niobium, tantalum, molybdenum, tungsten, and titanium-zirconium-molybdenum alloys. It reviews the factors that affect mechanical properties and formability during rolling and heat treatment. The effect of temperature on the formability of refractory metals is discussed. The article provides a description of the forming methods of sheet and preformed blanks using refractory metals. It also discusses the types of lubricants, including oils, soaps, waxes, silicones, graphite, and molybdenum disulphide, used in the forming of refractory metals.
Mechanical Joining by Forming
Authors: Rammohan Deepak , Gonzalez-Mendez Jose L.
Published: December 2018

Mechanical joining by forming includes all processes where parts being joined are formed locally and sometimes fully. This article focuses on the types, advantages, disadvantages, and applications of the various mechanical joining methods, namely, riveting, crimping, clinching, and self-pierce riveting.
Gases in Metals
Authors: Fruehan Richard J. , Anyalebechi Prince N.
Published: December 2018

This article reviews the solubilities of the common gases present in ferrous metals, such as cast irons, and nonferrous metals, such as aluminum, copper, magnesium, and their alloys. The kinetics of the relevant reactions, reactions during solidification, and possible methods of control or removal of the dissolved gases are discussed. The most common method for removing hydrogen from aluminum, copper, and magnesium is inert gas flushing. The article concludes with a discussion on overcoming gas porosity in ferrous and nonferrous metals.
Induction Furnaces
Authors: Perkul Ralph Y.
Published: December 2018

This article describes the principles and classifications of induction furnaces. The classifications of induction furnaces are coreless and channel. The electromagnetic stirring action in these furnaces is reviewed. The article provides information on various power supplies and water cooling systems for the induction furnaces. Furnace operators can increase the power supply utilization by the use of mechanical skimmers. The article describes the various lining materials used in induction furnaces, namely, silica, alumina, and magnesia. The crucible wall scrapers, ramming mixes, and lining push-out device used in induction furnaces are also reviewed. The article concludes with a discussion on two distinct ways of operating a coreless induction furnace: batch operation and tap-and-charge operation.
Skull Melting
Authors: Keough G.
Published: December 2018

Skull melting refers to the use of furnaces with water-cooled crucibles that freeze a solid “skull” of material on the crucible wall. This article describes the basic components, operating pressure, advantages, and applications of vacuum arc and induction skull melting furnaces.
Transport Phenomena During Solidification
Authors: Dantzig Jonathan A.
Published: December 2018

This article begins with balance equations for mass, momentum, energy, and solute and the necessary boundary conditions for solving problems of interest in casting and solidification. The transport phenomena cover a vast range of length and time scales, from atomic dimensions up to macroscopic casting size and from nanoseconds for interface attachment kinetics to hours for casting solidification. The article describes how to determine which phenomena are most important at the particular length and time scale for the problem. It concludes with several examples of the application of transport phenomena in solidification, focusing in particular on microstructure formation.
The Oxide Film Defect: The Bifilm
Authors: Campbell John
Published: December 2018

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.
Solidification During Casting of Metal-Matrix Composites
Authors: Rohatgi Pradeep , Schultz Benjamin , Gupta Nikhil , Daoud Atef
Published: December 2018

This article discusses the solidification of matrix alloy in cast metal matrix composites (MMCs). It begins with a discussion on the mixing techniques in reinforcement incorporation and wettability of reinforcement. It describes the solidification processes, such as stir mixing and melt infiltration, used in the synthesis of MMCs. The article also discusses the fundamentals of solidification process and presents a computational modeling of particle/solidification front interactions in metal-ceramic systems. The article concludes with information on nanocomposites.
Heat Treatment
Authors: Chaudhury Sujoy Krishna
Published: December 2018

This article provides an overview of heat treatment processes, namely, solution heat treatment, quenching, and natural and artificial aging. It contains a table that lists various heat treatment tempers commonly practiced for nonferrous castings. The article describes microstructural changes that occur due to the heat treatment of cast alloys.
Slurry Molding
Authors: Nelson Charles D. , Rasmussen Wayne , Jorstad John
Published: December 2018

This article discusses slurry molding that encompasses two distinct processes: plaster molding and ceramic molding. Plaster mold casting is a specialized casting process used to produce nonferrous castings that have greater dimensional accuracy, smoother surfaces, and more finely reproduced detail. The article describes three generally recognized plaster mold processes, namely, conventional plaster mold casting, the Antioch process, foamed plaster process. Ceramic molding techniques are based on processes that employ permanent patterns and fine-grained zircon and calcined, high-alumina mullite slurries for molding. The Shaw process and the proprietary Unicast processes are also discussed.
Horizontal Centrifugal Casting
Authors: Murty Y.V.
Published: December 2018

Horizontal centrifugal casting is used to cast parts having an axis of revolution. This article discusses the operations of various horizontal casting machines, such as flanged shaft machine, horizontal roller-type machine, and double-face plate machine. It describes the types of molds, such as expendable molds and permanent molds, used for centrifugal casting. The article also discusses the steps in casting process, namely, pouring, solidification, and babbitting. It provides information on the applications of the horizontal centrifugal casting.
Permanent Mold Casting
Authors: Tyler Don , Pischel Robert
Published: December 2018

This article provides information on metals that can be cast in permanent molds. It discusses the manual and automatic operations, design guidelines, advantages, disadvantages, and applications of the casting. The article describes the number of factors considered when designing and building the molds. It examines the effect of mold design on mold life. The article outlines the primary purposes, procedure, and application of mold coatings. The variables that determine mold temperature and control measures associated with mold temperature are reviewed. The article explains the effect of short-term and long-term variables on the dimensional accuracy of permanent mold castings. It concludes with information on the factors of the surface finish on permanent mold castings.
Copper Continuous Casting
Authors: Tyler Derek E. , Vierod Richard P.
Published: December 2018

This article reviews the history and methods of copper alloy continuous casting. The methods include vertical continuous casting and horizontal continuous casting. The article discusses the upcasting methods used in vertical continuous casting and strip casting used in horizontal continuous casting. The upcasting methods include Outokumpu upcasting method, Rautomead upwards vertical casting, and pressure upcasting. The article also describes the methods and processes of wheel casting and Ohno continuous casting.
Aluminum Fluxes and Fluxing Practice
Authors: Gallo Rafael , Neff David
Published: December 2018

Aluminum fluxing is a step in obtaining clean molten metal by preventing excessive oxide formation, removing nonmetallic inclusions from the melt, and preventing and/or removing oxide buildup on furnace walls. This article discusses the solid fluxes and gas fluxes used in foundries. It reviews the classification of solid fluxes depending on their use and function at the foundry operation. These include cover fluxes, drossing fluxes, cleaning fluxes, and furnace wall cleaner fluxes. The article also discusses the operational practices and applications of the flux injection in the foundries. It describes the applications of the aluminum fluxing such as crucible furnaces, transfer ladles, reverberatory furnaces, and holding/casting furnaces.
Copper and Copper Alloy Castings
Authors: Sadayappan Kumar , Sahoo Mahi , Michels Harold T.
Published: December 2018

The properties of copper alloys occur in unique combinations found in no other alloy system. This article focuses on the major and minor alloying additions and their impact on the properties of copper. It describes major alloying additions, such as zinc, tin, lead, aluminum, silicon, nickel, beryllium, chromium, and iron. The article discusses minor alloying additions, including antimony, bismuth, selenium, manganese, and phosphorus. Copper alloys can be cast by many processes, including sand casting, permanent mold casting, precision casting, high-pressure die casting, and low-pressure die casting. The article provides information on the types of copper castings and tabulates the nominal chemical composition and mechanical properties of several cast alloys.
Degassing
Authors: Neff David V.
Published: December 2018

Gas porosity is a major factor in the quality and reliability of castings. The major cause of gas porosity in castings is the evolution of dissolved gases from melting and dross or slag containing gas porosity. Degassing is the process of removing these gases. This article describes the methods of degassing aluminum, magnesium, and copper alloys. It provides information on sources of hydrogen in aluminum and gases in copper.
Casting Design and Geometry
Authors: Gwyn Michael
Published: December 2018

In terms of component design, casting offers a great amount of flexibility. This article discusses the parameters that can drive the geometry of casting design from a process standpoint. It provides information on the design of junctions and addresses considerations of secondary operations in design. The article describes the factors that control casting tolerances and provides specific tips for designing castings with uniform wall thickness and unequal sections, designing thin sections, designing for economical coring, designing for functional packaging, and core design principles. The choice of whether a component is best manufactured as welded, assembled, fabricated, forged, machined, or cast is based on the component geometry, production costs, and requirements in application. The article addresses these issues and provides a framework for analyzing all manners of manufacturing as possible conversion candidates. It concludes with a discussion on different metalcasting design projects.
Machining
Authors:   ASM Handbook Committee
Published: December 2018

Volume 16 covers machining technologies, including fundamentals, detailed descriptions of specific machining and grinding processes, guidelines for proper selection of cutting tool materials and cutting fluids, and recommendations for improved machining productivity and efficiency. The volume, featuring 1,300 illustrations and 620 tables, includes process capabilities, machines, cutting parameters plus variables, and applications of traditional machining processes such as turning, drilling, and milling. Mechanical, electrical, thermal, and chemical material removal procedures are also summarized. For information on the print version of Volume 16, ISBN 978-0-87170-022-3, follow this link.
Machining of Nickel and Nickel Alloys
Authors: Breitzig R.W.
Published: December 2018

Nickel-base alloys can be machined by techniques that are used for iron-base alloys. This article discusses the effects of distortion and microstructure on the machinability of nickel alloys. It tabulates the classification of nickel alloys based on machining characteristics. The article describes the machining operations performed on nickel alloys, such as turning, planing and shaping, broaching, reaming, drilling, tapping and threading, milling, sawing, and grinding. It provides information on the cutting fluids used in the machining of nickel alloys. The article also analyzes nontraditional machining methods that are suitable for shaping high-temperature, high-strength nickel alloys. These include electrochemical machining, electron beam machining, and laser beam machining.
Tribology of Nitrided and Nitrocarburized Steels
Authors: Senatorski J. , Tacikowski J. , Roliński E. , Lampman Steven
Published: December 2018

The surface of irons and steels can be hardened by introducing nitrogen (nitriding), nitrogen and carbon (nitrocarburizing), or nitrogen and sulfur (sulfonitriding) into the surface. This article lists the principal reasons for nitriding and nitrocarburizing, and summarizes the typical characteristics of nitriding processes along with a general comparison of carburizing processes in a table. It describes the two most common nitriding methods: gas nitriding and ion (plasma) nitriding. The article discusses the wear behavior of nitrided layers and the wear resistance of selected steels. Rolling-contact fatigue (RCF) occurs in rolling contacts such as bearings, rolls, and gears. The article provides a discussion on rolling-contact fatigue of nitrided steels for aerospace bearing components.
Carbon-Base (Diamondlike and Diamond) Coatings
Authors: Evans Ryan D.
Published: December 2018

This article describes two variations of carbon-base coatings: diamondlike carbon (DLC) coatings and polycrystalline diamond (PCD) coatings. It discusses the basics of a few deposition methods as they apply to industrially relevant coatings. The methods include deposition of tungsten-containing hydrogenated amorphous carbon films, deposition of tetrahedral amorphous carbon films, and deposition of silicon-incorporated hydrogenated amorphous carbon films. The most common deposition technologies for diamond films are also discussed. The article provides information on surface preparation for DLC and diamond deposition. It also provides a discussion on the coating composition and structure, mechanical and tribological properties, and applications of DLC and diamond coatings. The quality control techniques for DLC and diamond coatings are specified to meet customer requirements and ensure repeatable quality.
Gas-Lubricated Bearings
Authors: Wardle Frank
Published: December 2018

This article describes the characteristics of three types of gas bearings, such as aerostatic bearing, precision aerodynamic bearing (PAB), and compliant aerodynamic bearing (CAB). It discusses the applications for aerostatic bearings and advantages in lubricating a bearing with a compressible gas. The article also describes the different types of aerostatic bearings, such as annular thrust bearings and orifice-compensated journal bearings. It presents a discussion on load capacity and stiffness, friction and power loss, and stability and damping of the aerostatic bearings. The article provides a discussion on the types of PAB and CAB. The types include spiral groove annular thrust bearings, cylindrical journal bearings, three-sector journal bearings, tilting-pad journal bearings, and helical-grooved journal bearings. The types of CAB include foil bearings and pressurized-membrane bearings. The article concludes with a description of factors that influence materials selection for gas-lubricated bearings.
Surface Texturing
Authors: Podgornik Bojan
Published: December 2018

This article provides an overview of surface-texturing techniques. It describes the texturing parameters, namely, shape, depth, and width of the textured pattern, its aspect ratio (depth over width), texture area density, and orientation. The article explains the effect of these parameters on tribological behavior of textured surfaces. It provides information on various modeling approaches for surface texture. The article also discusses the beneficial effect of surface texturing.
Friction and Wear of Automotive and Aircraft Brakes
Authors: Hu Bo
Published: December 2018

This article focuses on friction and wear of automotive and aircraft brakes. It provides a comparison of friction and wear behaviors, frictional characteristics, and frictional performance of the friction materials. The article describes the components of brake friction materials and the classifications of brake lining materials. It discusses the effect of formulation compositions and manufacturing processes and the effect of braking operation conditions. The article provides information on aircraft brake linings, which operate under a wide range of kinetic energy conditions. The morphology effect of graphite on automotive brake drum and disk is explained. The article also describes the characteristics of specific wear rates for both normal and local cast iron in automotive brake drums and disk rotors. It provides information on noises, vibrations, and harshness caused by brake pads. The article concludes with information on physical and chemical testing of brakes and toxicity of brake formulation and regulations.
Tribology of Extrusion
Authors: Saha Pradip , Schmid Steven
Published: December 2018

This article discusses two basic forms of extrusion: cold and hot. It provides information on three types of extrusion processes, namely, direct extrusion, reverse extrusion, and hydrostatic extrusion. The article also discusses the mechanics, analysis, tooling and die design of extrusion as well as thermodynamics. The finite-element method suitable for simulation of metal forming processes is explained. The article examines the extrusion defects that are divided into three different categories including surface, subsurface, and internal type. It includes information on friction and lubrication modeling of extrusion processes. The article also discusses the fundamentals of extrusion technology of titanium alloys and aluminum. It concludes with information on two forms of wear in extrusion, namely, adhesive and abrasive wear.
Friction and Wear of Cobalt-Base Alloys
Authors: Ahmed Rehan , de Villiers-Lovelock Heidi
Published: December 2018

This article focuses on the tribological behavior of group 1, 2, and 3 cobalt-base alloys, namely, carbide-type wear-resistant alloys and laves-type wear-resistant alloys. The behavior includes hardness, yield strength and ductility, and fracture toughness. The article contains a table that lists the nominal compositions and typical applications of cobalt-base alloys. It discusses the properties and relative performance of specific alloys when subjected to the more common types of wear. These include abrasive wear, high-temperature sliding wear, rolling-contact fatigue wear, and erosive wear.
Introduction to Condition Monitoring
Authors: Skaf Zakwan
Published: December 2018

This article introduces the concept of condition monitoring (CM) and summarizes various techniques used for CM across the industrial sectors. The techniques include visual inspection, performance monitoring, vibration condition monitoring, vibration condition monitoring, lubricant oil analysis, acoustic emission testing, temperature monitoring, motor current signature analysis, and ultrasound emission. The article describes the evolution of condition-based maintenance in CM. It also describes the basics of integrated vehicle health management, a capability that enables a number of maintenance philosophies. The article concludes with a discussion on various condition monitoring in industrial sectors, including condition-monitoring techniques in nuclear power plants, road condition monitoring, and condition monitoring in wind turbines.
Lubricant Additives and Their Functions
Authors: Bardasz Ewa A.
Published: December 2018

This article focuses on lubricants classified as either internal combustion engine or nonengine lubricants, and the lubricant additives. The functional groups of chemically active and inert additives, as well as friction modifiers and other additives, are described in detail. The chemically active additives include dispersants, detergents, antiwear, and extreme-pressure agents, oxidation inhibitors, and rust and corrosion inhibitors. The chemically inert additives include emulsifiers, demulsifiers, pour-point depressants, foam inhibitors, and viscosity improvers. The article also discusses the multifunctional nature of additives and concludes with information on lubricant formulation.
Lubricants for Rolling-Element Bearings
Authors: Lugt Piet M.
Published: December 2018

This article discusses the functions of lubricants to prevent premature failure of rolling element bearings and the advantages of fluid lubrication. It describes the composition of refined mineral oil for rolling bearing applications. The article reviews the types and properties of nonpetroleum oils, such as polyglycols, phosphate esters, silicone fluids, dibasic acid esters, and fluorinated polyethers. It discusses the properties of greases, including grease speed limits, grease composition, relubrication intervals, corrosion prevention behavior, and grease compatibility. The article concludes with a discussion on polymeric lubricants and solid lubricants.
Fretting Wear
Authors: Shipway P.H.
Published: December 2018

Fretting is the small-amplitude oscillatory movement that can occur between contacting surfaces, which are nominally at rest. This article discusses fretting wear in mechanical components and the mechanisms of fretting wear. It describes the role of fretting conditions, such as fretting duration, slip amplitude, normal load, fretting frequency, contact geometry, type of vibration, and surface finish, as well as the role of environmental conditions. The article reviews the influence of an aqueous environment on the mechanism of fretting. The steps that can be taken to reduce or eliminate damage due to fretting are extremely diverse. The article presents some general indications of how to address the fretting wear problem.
Friction and Wear of Cemented Carbides
Authors: Wang Xiaohui
Published: December 2018

Cemented carbides, best known for their superior wear resistance, have a range of industrial uses more diverse than that of any other powder metallurgy product including metalworking and mining tools and wear-resistant components. This article discusses raw materials and manufacturing methods used in the production of cemented carbides, the physical and mechanical properties of carbides, and wear mechanisms encountered in service. Emphasis is placed on tungsten carbide-cobalt (WC-Co) or tungsten carbide-nickel (WC-Ni) materials as used in nonmachining applications. Nominal composition and properties of representative cemented carbide grades and their applications are listed in a table.
Wear of Steam Turbine and Gas Turbine Components
Authors: Anand K.
Published: December 2018

This article illustrates typical wear and friction issues encountered in gas and steam turbines and their consequences as well as commonly adopted materials solutions. It contains tables that present the summary of wear and friction related issues encountered in steam turbines and gas turbines. The article outlines the differences in the operating conditions and the nature of the components involved in gas and steam turbines. It discusses the constraints and applicable coating solutions for wear and friction issues, and concludes with a broad set of challenges that need to be addressed to improve performance and operability of gas and steam turbines.
Residual Strength of Composite Aircraft Structures with Damage
Authors: Poe C.C.
Published: December 2018

This article presents the damage tolerance criteria for military composite aircraft structures to safely operate the structures with initial defects or in-service damage. It describes the effects of defects, such as wrinkles in aircraft structures, and the reduction in compressive strength and tensile strength. The article reviews low velocity impacts in aircraft structures in terms of resin toughness, laminate thickness, specimen size and impactor mass, and post-impact fatigue. It explains the tension strength analysis, such as linear elastic fracture mechanics and R-curve methods, to predict the residual strength of the structures.
Robust Design
Authors: Ealey Lance A.
Published: December 2018

This article addresses problems, such as “in spec” dilemma and on-target key, associated with traditional approaches to quality. It discusses major robust design techniques, tools, and concepts, such as quality loss function, parameter design, tolerance design, signal-to-noise ratio, technology development, and orthogonal arrays.
Risk and Hazard Analysis in Design
Authors: Kardos G.
Published: December 2018

Risk and hazard analysis can be effectively used during design reviews to provide valuable feedback to the design to avoid failures. This article discusses the types of risks, namely, real risk, statistical risk, predicted risk, and perceived risk. It describes the principle and technical methods of risk/hazard analysis practiced in the industry to identify possible hazards and the resources necessary to avoid or reduce risks. These methods include the failure mode and effect analysis, fault tree analysis, event tree analysis, risk/benefit analysis, safety analysis, and probabilistic estimates.
Effects of Surface Treatments on Materials Performance
Authors: Marder Arnold R.
Published: December 2018

Surface treatments are used in a variety of ways to improve the material properties of a component. This article provides information on surface treatments that improve service performance so that the design engineer may consider surface-engineered components as an alternative to more costly materials. It describes solidification surface treatments such as hot dip coatings, weld overlays, and thermal spray coatings. The article discusses deposition surface treatments such as electrochemical plating, chemical vapor deposition, and physical vapor deposition processes. It explains surface hardening and diffusion coatings such as carburizing, nitriding, and carbonitriding. The article also tabulates typical characteristics of carburizing, nitriding, and carbonitriding diffusion treatments.
Design for High-Temperature Applications
Authors: Woodford David A.
Published: December 2018

This article reviews the basic mechanisms of elevated-temperature behavior and associated design considerations, with an emphasis on metals. It discusses the key concepts of elevated-temperature design. These include plastic instability at elevated temperatures; deformation mechanisms and strain components associated with creep processes; stress and temperature dependence; fracture at elevated temperatures; and environmental effects. The article describes the basic presentation and analysis methods for creep rupture. It provides information on the application of these methods to materials selection and the setting of basic design rules. The article examines the limitations of high-temperature components as well as the alternative design approaches and tests for most high-temperature components.
Properties Needed for Electronic and Magnetic Applications
Authors: Rymaszewski Eugene J.
Published: December 2018

This article presents an overview of the electric and magnetic parameters and discusses the significance of these parameters for electronic applications. It describes the components of analog and digital electronic circuits. The article reviews the augmenting technologies: magnetic and special technologies such as electrooptical.
Design with Composites
Authors: Diefendorf R.J.
Published: December 2018

This article begins with a discussion on fiber-reinforced composite materials and describes the generic behavior and structure/property relationships of composites. The article summarizes lamina properties and presents equations that help in the calculation of lamina properties. Composite laminates are constructed from lamina with uniaxial fiber orientation and frequently from textile fabrics as well. The article explains the characteristics of symmetric in-plane and through-thickness laminates; asymmetric in-plane and symmetric through-thickness laminates; asymmetric laminates; and curved laminates. It provides information on controlled thermal expansion composites, metal-matrix composites, and ceramic-matrix composites. The article illustrates the types of bonded joints and concludes with a discussion on design for manufacturing.
Modeling of Manufacturing Processes
Authors: Paul Anand J.
Published: December 2018

Manufacturing processes typically involve the reshaping of materials from one form to another under a set of processing conditions. This article discusses the two classification schemes of modeling for manufacturing processes, namely, on-line or off-line models and empirical, mechanistic, or deterministic models along with their important considerations. It describes the various aspects of modeling of deformation processes, casting operations, and fusion welding processes, with examples.