In x-ray diffraction residual stress measurement, the strain in the crystal lattice is measured, and the residual stress producing the strain is calculated, assuming a linear elastic distortion of the crystal lattice. This article provides a detailed account of the plane stress elastic model, and describes the most common methods of x-ray diffraction residual stress measurement, namely, single-angle and two angle techniques. It elaborates the major steps involved in x-ray diffraction residual stress measurement, explaining the possible sources of error in stress measurement. The article also outlines the applications of x-ray diffraction residual stress measurement with examples.

The article provides an introduction on the importance of alloying elements on corrosion behavior of nickel alloys and describes the applications of heat-resistant alloys to resist corrosion. It focuses on the metallurgical effects, mainly the effect of internal factors, including chemical composition and microstructure of the alloy, and the external factors, including electrolyte composition, temperature, and electrode potential, on the corrosion behavior of corrosion-resistant alloys. The article also discusses the implication of changing the alloy microstructure by second-phase precipitation, cold working, and cast and wrought forms on the corrosion behavior of high-nickel alloys.

This article focuses on the properties of conventional wrought superalloys based on nickel, iron, and cobalt, as well as on the properties of alloys produced from powder. The powder metallurgy (P/M) category includes alloys that were originally developed as casting alloys; new alloy compositions developed specifically to benefit from powder processing; and oxide dispersion strengthened alloys (particularly those produced by mechanical alloying). The article discusses some of the applications of superalloys and emphazises the interplay between chemical composition, microstructure, consolidation method, mechanical properties and surface stability of wrought nickel alloys. Vacuum melting processes are a necessity for many nickel- and iron-nickel-base alloys because of the presence of aluminum and titanium as solutes. Cobalt-base alloys do not usually contain these elements and may be melted in air. An appendix to this article presents the property data and corresponding information on a family of cobalt-chromium-tungsten-carbon alloys that use P/M processing.

This article addresses the general welding characteristics common to both solid-solution-strengthened and precipitation-hardened nickel-, iron-, and cobalt alloys.

This article provides information on nickel alloying elements, and the heat treatment processes of various nickel alloys for applications requiring corrosion resistance and/or high-temperature strength. These processes are homogenization, annealing, solution annealing, solution treating, stabilization treatment, age hardening, stress relieving, and stress equalizing. Discussion of furnaces, fixtures, and atmospheres is included. Nickel alloys used for the heat treatment processes include corrosion-resistant nickel alloys, heat-resistant nickel alloys, nickel-beryllium alloys, special-purpose alloys such as nitinol shape memory alloys, low-expansion alloys, electrical-resistance alloys and soft magnetic alloys. Finally, the article focuses on heat treatment modeling for selecting the appropriate heat treatment process.

This article provides a detailed account of x-ray diffraction (XRD) residual-stress techniques. It begins by describing the principles of XRD stress measurement, followed by a discussion on the most common methods of XRD residual-stress measurement. Some of the procedures required for XRD residual-stress measurement are then presented. The article provides information on measurement of subsurface stress gradients and stress relaxation caused by layer removal. The article concludes with a section on examples of applications of XRD residual-stress measurement that are typical of industrial metallurgical, process development, and failure analysis investigations undertaken at Lambda Research.

This article briefly reviews the various metallurgical or environmental factors that cause a weakening of the grain boundaries and, in turn, influence the occurrence of intergranular (IG) fractures. It discusses the mechanisms of IG fractures, including the dimpled IG fracture, the IG brittle fracture, and the IG fatigue fracture. The article describes some typical embrittlement mechanisms that cause the IG fracture of steels.

This article provides an overview of common quenching media, the factors involved in the mechanism of quenching, and process variables, namely, surface condition, mass and section size of the workpiece, and flow rate of the quenching liquid. It describes the methods of quenchant characterization using hardening-power and cooling-power tests. The article discusses the fundamentals involved in heat-transfer coefficient and heat flux of quenching processes. This discussion is followed by various actual examples of applications of these methods using simplified equations. Quenchant evaluation, classification, selection, and maintenance are reviewed in detail. The article addresses the various reasons for quench oil variability and complications due to aging and contamination.

This article discusses the corrosion of metals and nonmetals by dry chlorine, refrigerated liquid chlorine, dry gaseous chlorine, moist chlorine, selected mixed gases with chlorine, and chlorine-water. It also provides information on the handling of commercial chlorine.

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.

Stress-relief heat treating of steel is the uniform heating of a structure to a suitable temperature below the transformation range, holding at this temperature for a predetermined period of time, followed by uniform cooling. This article provides information on the sources of residual stress, briefly describes the factors influencing the relief of residual stresses, and discusses the various thermal stress-relief methods. It contains tables that provide a summary of compressive and tensile residual stresses at the surface of parts fabricated by common manufacturing processes. The article presents the temperature range of alloy steels for stress-relief heat treating and describes the importance of stress relief of springs.

Weldability refers to the ease of welding a material under the imposed fabrication conditions to perform satisfactorily during service. This article is a comprehensive collection of tables that summarize the general weldability of cast irons, steels, nonferrous metals, and their alloys by common fusion welding processes.

Density allows for the conversion of uniform corrosion rates from units of weight (or mass) loss per unit area per time to thickness per unit time. This article contains a table that lists the density of metals, such as aluminum, copper, iron, stainless steel, magnesium, and lead, and their alloys.

This article reviews high-temperature corrosion of furnace parts used in heat-treating furnaces. It provides a comparison of cast and wrought materials in the context of their general considerations, advantages, and applications. The article provides information on the heat-resistant alloys used for parts that go through the furnaces, including trays, fixtures, conveyor chains and belts, and quenching fixtures and parts, and the parts that remain in the furnace such as combustion tubes, radiant tubes, burners, thermowells, roller and skid rails, baskets, pots, retorts, muffles, and drive and idler drums. The article also reviews the material characteristics of silicon/silicon carbide composite and reaction-bonded silicon carbide as used in radiant tubes.

This article begins with a discussion of the basic fracture modes, including dimple ruptures, cleavages, fatigue fractures, and decohesive ruptures, and of the important mechanisms involved in the fracture process. It then describes the principal effects of the external environment that significantly affect the fracture propagation rate and fracture appearance. The external environment includes hydrogen, corrosive media, low-melting metals, state of stress, strain rate, and temperature. The mechanism of stress-corrosion cracking in metals such as steels, aluminum, brass, and titanium alloys, when exposed to a corrosive environment under stress, is also reviewed. The final section of the article describes and shows fractographs that illustrate the influence of metallurgical discontinuities such as laps, seams, cold shuts, porosity, inclusions, segregation, and unfavorable grain flow in forgings and how these discontinuities affect fracture initiation, propagation, and the features of fracture surfaces.

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.

Superalloys are nickel, iron-nickel, and cobalt-base alloys generally used for high-temperature applications. Superalloys are used in aircraft, industrial, marine gas turbines, nuclear reactors, spacecraft structures, petrochemical production, orthopedic and dental prostheses, and environmental protection applications. This article discusses the material characteristics, phases, structures, and systems of superalloys. It describes the processing of superalloys, including primary and secondary melting, deformation processing (conversion), powder processing, investment casting, and joining methods. The article also describes the properties, microstructure, and thermal exposure of superalloys. It further discusses the effects of environmental factors on superalloys, including oxidation and hot corrosion. Protective coatings are also discussed. The article provides information on the mechanical properties and chemical composition of nickel, iron, and cobalt-base superalloys in both the cast and wrought forms.

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.

This article provides a discussion on cutting tools, their materials and design; cutting fluids; and various aspects of machining operations of heat-resistant alloys, with several examples. Operations such as turning, planing and shaping, broaching, drilling, reaming, counterboring and spotfacing, tapping and thread milling, milling, sawing, and grinding are discussed. Nominal compositions of wrought heat-resistant alloys and nickel-base heat-resistant casting alloys, as well as compositions of cobalt-base heat-resistant casting, iron-base heat-resistant casting, and mechanically alloyed (oxide dispersion strengthened) products are also listed.

The high-temperature corrosion processes that are most frequently responsible for the degradation of furnace accessories are oxidation, carburization, decarburization, sulfidation, molten-salt corrosion, and molten-metal corrosion. This article discusses each corrosion process, along with the corrosion behavior of important engineering alloys. It describes the corrosion of plating, anodizing, and parts of pickling equipment such as tanks, wirings and bus bars, racks, anode splines, pumps, and heaters.