This chapter describes important requirements for ferrous and nonferrous alloys used for gears. Wrought surface-hardening and through-hardening carbon and alloy steels are the most widely used of all gear materials and are emphasized in this chapter. The processing characteristics of gear steels and the bending fatigue strength and properties of carburized steels are reviewed. In addition to wrought steels, the chapter provides information on the other iron-base alloys that are used for gears, namely cast carbon and alloy steels, gray and ductile cast irons, powder metallurgy irons and steels, stainless steels, and tool steels. In terms of nonferrous alloys, the chapter addresses copper-base alloys, die cast aluminum alloys, zinc alloys, and magnesium alloys.

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.

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 begins with information on the historical development of aluminum alloy castings. It then covers the basic factors involved in the selection of a casting process. This is followed by sections describing the various categories of casting processes and their variants: expendable mold gravity-feed casting, nonexpendable (permanent) mold gravity feed casting, and pressure die casting. Next, the chapter describes the technologies used to produce premium engineered castings and when such castings may be relevant. The chapter concludes with descriptions of other process technologies used with castings, including metallurgical bonding, metal-matrix composites, and hot isostatic pressing.

This article discusses the composition, properties, and behaviors of zinc and its alloys. It explains where cast and wrought zinc alloys are used, describes commercial designations and grades, and discusses the effect of various alloying elements on properties and performance.

Magnesium occupies the highest anodic position on the galvanic series and can be subject to severe corrosion. The corrosion problem is due to the impurity elements iron, nickel, and copper. However, the use of higher-purity magnesium alloys has led to corrosion resistance approaching that of some of the competing aluminum casting alloys. This chapter begins with a general overview of magnesium metallurgy and alloy designations and moves on to discuss in detail the nominal compositions, mechanical properties, heat treatment, fabrication, and corrosion protection of magnesium casting alloys and wrought magnesium alloys. It also discusses the nominal compositions, properties, and applications of commercially pure zinc, zinc casting alloys, and wrought zinc alloys.

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 chapter is a collection of tables listing: cast alloy designations of Aluminum Association, along with their general applications; the chemical compositions of the frequently used alloys for gravity permanent molds, low-pressure permanent molds, squeeze castings, and die castings; the typical tensile properties of die cast alloys; and the designations of different heat treatments and their description. The tables also list the temperatures and times of typical heat treatment cycles for different permanent mold cast alloys; typical components in sand, gravity, and low-pressure permanent mold castings and die castings, the functional requirements of each process, and the corresponding suitable alloys and heat treatments; and alloys that are high vacuum die cast for structural castings. The chapter also presents examples of photomicrographs of some alloys cast by different processes.

This data set contains approximately 50 growth curves for a wide range of aluminum casting alloys at various temperatures. Growth curves are used to determine the dimensional changes that must be anticipated during service in applications where close dimensional tolerances are required. Hardness curves are provided for many of the alloys. The hardness values are from corresponding aging response studies in which measurements were made on individual lots considered representative of the respective alloys and tempers.

This appendix contains abbreviations and symbols related to aluminum alloy castings.