This chapter covers mechanical properties, microstructures, chemical compositions, manufacturing processes, and engineering of gating practices for several applications of gray, white, and alloyed cast irons. It begins with a description of material standards, followed by a section providing information on the practice of stress relieving. Next, the chapter details various ways of eliminating slag entrainment while designing gating and venting systems. Several factors related to the establishment of the optimum pouring rate and time are then covered. Further, the chapter discusses the technology of unalloyed or low-alloyed gray iron castings and white iron and high-alloyed cast irons. Finally, it describes the casting defects that are associated with cast iron and the processes involved in solving these defects. The article includes a number of figures illustrating the topics discussed.

This chapter discusses the effect of composition and cooling rate on the microstructure and properties of cast irons and explains how they differ from steel. It describes the conditions under which white, gray, mottled (chilled), and nodular (ductile) cast irons are produced, and examines the growth mechanisms and structural details that set them apart. It also discusses the formation of compacted (vermicular) graphite and malleable iron, and compares and contrasts the composition, properties, and heat treatment of whiteheart and blackheart malleable types.

The commercial relevance of cast irons is best understood in the context of the iron-carbon phase diagram, where their composition places them near the eutectic point, which sheds light on why they melt at lower temperatures than steel and why they can be cast into more intricate shapes. This chapter examines these unique properties and how they are derived. It begins by describing the basic metallurgy of cast iron, focusing on the eutectic reaction. It explains how to control the reaction and thus properties of cast iron by overcooling and inoculation. The chapter also discusses composition, microstructure, heat treatments, and the classification and casting characteristics of white, gray, ductile, malleable, compacted graphite, and special cast irons.

The properties of cast iron are determined primarily by the form of carbon they contain, which in turn, is controlled by modifying compositions and cooling rates during casting. Certain alloys (such as Si, Al, Ni, Co, and Cu) promote graphite formation, while others (such as S, V, Cr, Sn, Mo, and Mn) promote the formation of cementite. This chapter examines the relative potencies of these alloys and their effect on microstructure. It covers the five most common commercial cast irons, including white, gray, ductile, malleable, and compacted graphite, describing their compositional ranges, distinguishing features, advantages, limitations, and applications.

This chapter provides a detailed analysis of the cyclic stress-strain behavior of materials under uniaxial stress and strain cycling. It first considers the case of a stable material under constant-amplitude strain cycling then broadens the discussion to materials that harden or soften with continued strain reversals. It compares and contrasts the response patterns of such materials, explaining how the movement of dispersed particles and dislocations influences their behavior. It then examines the behavior of materials under uniaxial strain reversals of varying amplitude and explains how to construct double-amplitude stress-strain curves that account for complex straining histories. For special cases, those involving complex materials such as gray cast iron or highly complex straining patterns, the chapter presents other methods of analysis, including the rainflow cycle counting method, mechanical modeling based on displacement-limited elements, Wetzel’s method, and deformation modeling. It also explains the difference between force cycling and stress cycling and presents alternate techniques for predicting whether a material will become harder or softer in response to strain cycling.

This article covers the metallurgy and properties of gray irons. It describes the classes or grades of gray iron, the types of applications for which they are suited, and the corresponding compositional ranges. It discusses the role of major, minor, and trace elements, how they are added, and how they affect various properties, behaviors, and processing characteristics. It explains how silicon, chromium, and nickel, in particular, improve high-temperature, corrosion, and wear performance.