This article addresses two issues on thermodynamics, namely, the calculation of solubility lines and the calculation of the activity of various components. It discusses alloying elements in terms of their influence on the activity of carbon. The article describes the desulfurization and deoxidation of cast iron and steel. It illustrates the thermodynamics of the iron-carbon system and the iron-silicon system. The article examines solubility and saturation degrees of carbon in multicomponent iron-carbon systems. One of the main applications of the thermodynamics of the iron-carbon system is the calculation of structure-composition correlations. The article concludes with information on the structural diagrams for cast iron: the Maurer diagram and the Laplanche diagram.

This article describes different methods by which the composition of cast iron can be analyzed. It provides particular emphasis on the methods for evaluating the graphitization potential of a melt with prescribed limits on carbon, silicon, and alloying elements. The article discusses the effect of cooling rate on the graphitization of a given composition by chill and wedge tests. Thermal analysis of cooling curves gives excellent information about the solidification and subsequent cooling of cast iron alloys. The article presents some applications of the cooling curve analysis and explains the evaluation of carbon-silicon contents, graphite shape, graphite nucleation, and contraction-expansion balance. It illustrates the use of an immersion steel sampling device for compacted graphite iron production and provides information on the ferrite-pearlite ratio in ductile iron.

Homogenization heat treatment can be useful for improving the performance and life of an alloy while in service or for improving the processability during fabrication and hot working. This article describes the identification of incipient melt point, slowest-diffusing elements, and microstructural scale for homogenization of metal alloys. It also discusses the CALPHAD software to optimize the homogenization heat treatment and the Scheil module of the commercial thermodynamic modeling software.

Cast stainless steels are usually specified on the basis of composition by using the alloy designation system established by the Alloy Casting Institute. This article discusses the corrosion behavior of heat-resistant alloys due to oxidation, sulfidation, and carburization. It describes the influence of the metallurgy of corrosion-resistant stainless steels on general corrosion, intergranular corrosion, localized corrosion, corrosion fatigue, and stress corrosion.

This article reviews the corrosion behavior of intermetallics for the modeling of the corrosion processes and for devising a strategy to create corrosion protective systems through alloy and coating design. Thermodynamic principles in the context of high-temperature corrosion and information on oxidation; sulfidation; hot corrosion of NiAl-, FeAl-, and TiAl-based intermetallics; and silicides are included. The article explores the thermodynamic consideration, ordering influencing kinetics, stress-cracking corrosion, and hydrogen embrittlement of aqueous corrosion. It also explains the practical issues dealing with the corrosion problems.

This article summarizes a physical model of an interface structure and shows how the model helps in optimizing atomistic modeling studies. It presents the orientation relationship of the interface structure to define the mutual crystallographic position of adjacent crystals. The article describes the model-informed atomistic modeling of the interface structures for interpolating the results of atomistic modeling to predict the properties of interfaces. Theories to predict low-energy orientation relationships are described. The article discusses the use of the localization parameter, such as shear modulus, bonding energy, and transformations, for prediction of interface structures. It provides information on the application of the atomistic modeling of interface structure to predict interface reaction mechanisms.

Oxide dispersion-strengthened (ODS) alloys are produced by mechanical alloying, a process by which base metals and alloying particles are powdered together forming a metal-matrix composite. This article discusses the production of ODS superalloy powders and subsequent processing steps, including consolidation, hot rolling, heat treating, and the fabrication of mill products. It also discusses the nominal composition and microstructure of commercial ODS alloys, including nickel, iron, and aluminum-base systems, and provides detailed information on their mechanical, physical, oxidation, and hot-corrosion properties.

Hardenable steels with high-alloy content includes a family of nickel-cobalt steels with high strength and high toughness. This article describes various heat treatments, namely, normalizing, annealing, hardening, tempering, stress relieving, overaging, quenching, refrigeration, and straightening treatment, applied to HP9-4-20, HP9-4-25, HP9-4-30, and HP9-4-45 steels. These steels have high fracture toughness when heat treated to very high strength levels. The article also describes heat treatments applied to other alloys such as AF 1410, AerMet 100, AerMet 310, and AerMet 340, which provide a good combination of high strength and toughness that make them attractive for aerospace application. It also presents tables that provide information on the effect of aging temperatures and heat treatment on mechanical properties and impact energy of these steels.

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.

Stress-corrosion cracking (SCC) is a cracking phenomenon that occurs in susceptible alloys, and is caused by the conjoint action of tensile stress and the presence of a specific corrosive environment. This article provides an overview of the anodic dissolution mechanisms and cathodic mechanisms for SCC. It discusses the materials, environmental, and mechanical factors that control hydrogen embrittlement and SCC behavior of different engineering materials with emphasis on carbon and low-alloy steels, high-strength steels, stainless steels, nickel-base alloys, aluminum alloys, and titanium alloys.

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.

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.

Titanium alloys are often used in highly corrosive environments because they are better suited than most other materials. The excellent corrosion resistance is the result of naturally occurring surface oxide films that are stable, uniform, and adherent. This article offers explanations and insights on the most common forms of corrosion observed with titanium alloys, including general corrosion, crevice corrosion, anodic pitting, hydrogen damage, stress-corrosion cracking, galvanic corrosion, corrosion fatigue, and erosion-corrosion. It also provides practical strategies for expanding the useful application range for titanium and includes a comprehensive overview of available corrosion data.

Laser surface hardening is a noncontact process that provides a chemically inert and clean environment as well as flexible integration with operating systems. This article provides a brief discussion on the various conventional surface-modification techniques to enhance the surface and mechanical properties of ferrous and nonferrous alloys. The techniques are physical vapor deposition, chemical vapor deposition, sputtering, ion plating, electroplating, electroless plating, and displacement plating. The article describes five categories of laser surface modification, namely, laser surface heat treatment, laser surface melting such as skin melting or glazing, laser direct metal deposition such as cladding, alloying, and hardfacing, laser physical vapor deposition, and laser shock peening. The article provides detailed information on absorptivity, laser scanning technology, and thermokinetic phase transformations. It also describes the influence of cooling rate on laser heat treatment and the effect of processing parameters on temperature, microstructure, and case depth hardness.

This article commences with a discussion on the characteristics of stress-corrosion cracking (SCC) and describes crack initiation and propagation during SCC. It reviews the various mechanisms of SCC and addresses electrochemical and stress-sorption theories. The article explains the SCC, which occurs due to welding, metalworking process, and stress concentration, including options for investigation and corrective measures. It describes the sources of stresses in service and the effect of composition and metal structure on the susceptibility of SCC. The article provides information on specific ions and substances, service environments, and preservice environments responsible for SCC. It details the analysis of SCC failures, which include on-site examination, sampling, observation of fracture surface characteristics, macroscopic examination, microscopic examination, chemical analysis, metallographic analysis, and simulated-service tests. It provides case studies for the analysis of SCC service failures and their occurrence in steels, stainless steels, and commercial alloys of aluminum, copper, magnesium, and titanium.