The refractory metals include niobium, tantalum, molybdenum, tungsten, and rhenium. These metals are considered refractory because of their high melting points, high-temperature mechanical stability, and resistance to softening at elevated temperatures. This article discusses the composition, properties, fabrication procedures, advantages and disadvantages, and applications of these refractory metals and their alloys. A comparison of some of the properties of the refractory metals with those of iron, copper, and aluminum is given in a table. The article concludes with a brief section on refractory metal protective coatings.

Carbon and low-alloy steels in high-temperature service are vulnerable to the effects of hydrogen attack, which include severe loss in tensile and rupture strengths as well as ductility. As the chapter explains, when steel is in contact with hydrogen molecules at elevated temperatures, hydrogen atoms can be absorbed at the surface and then diffuse into the metal. Hydrogen atoms in the metal then react with iron carbide forming methane gas which can accumulate at grain boundaries and other interfaces. The chapter describes two applications, one in coal-fired boilers, the other in petroleum refining, where hydrogen attack was observed. It documents the extent of the damage in each case and identifies the source of the hydrogen.

This article discusses the steps in the primary processing of stainless steels: melting, refining, remelting, casting, and hot rolling. It provides information of the major categories of defects in hot rolled stainless steels, namely hot mill defects, inclusion-related defects, and hot ductility-related defects.

This chapter reviews the basic chemistry of beryllium metals and compounds, including beryllium hydroxide, beryllium carbonates, beryllium fluoride, and beryllium chloride. It discusses the uses as well as application challenges of various forms of beryllium and includes information on their chemical properties and reactions.

This chapter discusses the effects of metallurgical factors on the corrosion resistance of magnesium alloys. The factors are chemical composition, heat treating, grain size, and cold-work effects. The chapter describes the causes of corrosion failures in magnesium alloys, namely heavy-metal contamination, blast residues, flux inclusions, and galvanic attack.

This chapter describes the processes involved in alloy production, including melting, casting, solidification, and fabrication. It discusses the effects of alloying on solidification, the formation of solidification structures, supercooling, nucleation, and grain growth. It describes the design and operation of melting furnaces as well as melting practices and the role of fluxing. It also discusses casting methods, nonferrous casting alloys, and atomization processes used to make metal powders.

Water chemistry is a factor in nearly all boiler tube failures. It contributes to the formation of scale, biofilms, and sludge, determines deposition rates, and drives the corrosion process. This chapter explains how water chemistry is managed in boilers and describes the effect of impurities and feedwater parameters on high-pressure boiler components. It discusses deposition and scaling, types of corrosion, and carryover, a condition that occurs when steam becomes contaminated with droplets of boiler water. The chapter also covers water treatment procedures, including filtration, chlorination, ion exchange, demineralization, reverse osmosis, caustic and chelant treatment, oxygen scavenging, and colloidal, carbonate, phosphate, and sodium aluminate conditioning.

This article discusses the weldability and fusion weld properties of refractory metal alloys. The alloys discussed include tantalum, niobium, rhenium, molybdenum, and tungsten.

Magnesium, by volume, is two-thirds the weight of aluminum and one-quarter the weight of steel. It also has good damping capacity, giving it an edge over other metals in high-vibration environments. This chapter discusses the basic metallurgy, alloy designations, compositions, and mechanical properties of cast and wrought magnesium alloys. It also describes the processes used to produce magnesium parts, the causes and effects of corrosion, and the use of protective coatings and treatments.

This article discusses the composition, structures, properties, and behaviors of aluminum alloys and explains how they correspond to specific alloying elements. It begins with an overview of the general characteristics of wrought and cast aluminum alloys, the four-digit classification system by which they are defined, and the applications for which they are suited. It then explains how primary alloying elements, second-phase constituents, and impurities affect yield strength, phase formation, and grain size and how they induce structural changes that help refine certain alloys. The article also explains how primary alloying elements affect corrosion and wear behaviors and how they influence fabrication processes such as forming, forging, welding, brazing, and soldering.

This chapter describes the causes of cracking, embrittlement, and low toughness in carbon and low-alloy steels and their differentiating fracture surface characteristics. It discusses the interrelated effects of composition, processing, and microstructure and contributing factors such as hot shortness associated with copper and overheating and burning as occur during forging. It addresses various types of embrittlement, including quench embrittlement, tempered-martensite embrittlement, liquid-metal-induced embrittlement, and hydrogen embrittlement, and concludes with a discussion on high-temperature hydrogen attack and its effect on strength and ductility.

Aluminum generally has excellent resistance to corrosion and gives years of maintenance-free service in natural atmospheres, fresh waters, seawater, many soils and chemicals, and most foods. This chapter explains why aluminum and aluminum alloys are naturally resistant to corrosion and describes the conditions and circumstances under which their natural defenses break down. It discusses the causes and forms of corrosion observed in aluminum alloys and the effect of composition, microstructure, processing history, and environmental variables such as impurities, fluid flow, surface area, pressure, and temperature.

This article examines the composition and properties of magnesium and its alloys. It discusses alloy and temper designations, applications and product forms, and commercial alloy systems, and explains how alloying elements affect physical and mechanical properties, processing characteristics, and corrosion behaviors.

The physical properties of a material are those properties that can be measured or characterized without the application of force and without changing material identity. This chapter discusses in detail the common physical properties of metals, namely density, electrical properties, thermal properties, magnetic properties, and optical properties. Some physical properties for a number of metals are given in a table.

This chapter discusses the processes, procedures, and equipment used in the production of iron, steel, aluminum, and titanium alloys. It describes the design and operation of melting and refining furnaces, including blast furnaces, basic oxygen and electric arc furnaces, vacuum induction melting furnaces, and electroslag and vacuum arc remelting furnaces. It also covers casting, rolling, and annealing procedures and describes the basic steps in aluminum and titanium production.

This chapter explains how to safely prepare beryllium alloy samples for metallographic analysis. It describes grinding, polishing, and etching procedures in detail. It also discusses the identification of major and minor constituents and the general appearance of beryllium microstructure.

Aluminum casting alloy compositions parallel those of wrought alloys in many respects. However, because work hardening plays no significant role in the development of casting properties, the use and purposes of some alloying elements differ in casting alloys versus wrought alloys. This chapter provides information on specifications and widely used designation systems and alloy nomenclature for aluminum casting alloys. It describes the composition of seven basic families of aluminum casting alloys: aluminum-copper, aluminum-silicon-copper, aluminum-silicon, aluminum-silicon-magnesium, aluminum-magnesium, aluminum-zinc-magnesium, and aluminum-tin. The chapter discusses the effects of alloying elements on the properties of cast aluminum. It provides information on various alloys that are grouped with respect to their applications or major performance characteristics.

Copper is often used in the unalloyed form because pure copper is more conductive than copper alloys. Alloying elements are added to optimize strength, ductility, and thermal stability, with little negative effect on other properties such as conductivity, fabricability, and corrosion resistance. This chapter covers the classification, composition, properties, and applications of copper alloys, including brasses, bronzes, copper-nickel, beryllium-copper, and casting alloys. It also examines wrought copper alloys and pure coppers. The chapter begins with an overview of the copper production process and concludes with a discussion on corrosion resistance.

Managing corrosion continues to be a challenge for operators of modern boilers worldwide. This chapter addresses the corrosion-related problems that can occur in boilers burning municipal solid waste (MSW). It describes corrosion mechanisms associated with different environments and alloys. It also discusses corrosion protection methods for furnace waterwalls and superheater tubes in waste-to-energy boilers.

This chapter discusses various processes involved in the production of steel from raw materials to finished mill products. The processes include hot rolling, cold rolling, forging, extruding, or drawing. The chapter provides a detailed description of two main furnaces used for making steel: the electric arc furnace and the basic oxygen furnace. It also provides information on the classification and specifications for various steels, namely, plain carbon steels, low-carbon steels, medium-carbon plain carbon steels, and high-carbon plain carbon steels. The chapter concludes with a general overview of the factors influencing corrosion in iron and steel and a brief discussion of corrosion-resistant coatings.