The main factors affecting the mechanical properties of compacted graphite irons both at room temperatures and at elevated temperatures are composition, structure (nodularity and matrix), and section size. This article presents a comparison between some properties of flake graphite (FG), compacted graphite (CG), and spheroidal graphite (SG) irons in a table. It discusses the effects of composition, structure, and section size on the mechanical properties of compacted graphite irons. The compressive and shear properties, modulus of elasticity, impact properties, fatigue strength, and elevated-temperature properties of compacted graphite irons are also reviewed.

Compacted graphite iron (CGI) invariably includes some nodular (spheroidal) graphite particles, giving rise to the definition of the microstructure in terms of percent nodularity. This article discusses the graphite morphology and mechanical and physical properties of CGI. The mechanical and physical properties of CGI with ferritic and pearlitic matrix structures are summarized in a table. The article describes the standards for CGI, with the definition of the grades based on the minimum tensile strength. It also provides information on the applications of compacted graphite iron castings.

This article discusses the chemical composition, castability, mechanical properties at room temperature and elevated temperature, and physical properties of compacted graphite (CG) cast iron. The change in graphite morphology from the flake graphite (FG) in the base iron to the CG in the final iron is achieved by liquid treatment with different minor elements. CG irons have strength properties close to those of spheroidal graphite (SG) irons, at considerably higher elongations than those of FG iron, and with intermediate thermal conductivities. The main factors affecting the mechanical properties of CG irons both at room temperatures and at elevated temperatures are composition, structure (nodularity and matrix), and section size. The article also discusses the applications of CG irons that stem from their relative intermediate position between FG and SG irons. The tables in the article list the values for tensile properties, hardness, thermal conductivity, fatigue strengths, endurance ratios, and compressive properties of CG, FG, and SG irons.

Ductile iron, also known as nodular iron or spheroidal graphite iron, is second to gray iron in the amount of casting produced. This article discusses the common grades of ductile iron that differ primarily by the matrix structure that contains the spherical graphite. The grades of ductile iron designated by their tensile properties in the specification ASTM A536 are presented in a table. The article various reviews factors, such as microstructure, composition, and section effect, affecting the mechanical properties of ductile iron. It discusses the hardness properties, tensile properties, shear and torsional properties, damping capacity, compressive properties, fatigue properties, and fracture toughness of ductile iron. The article concludes with information on the applications of austempered ductile iron.

The morphology of the graphite particles in compacted graphite iron (CGI) is intermediate to the graphite particles found in gray iron or ductile iron. This article discusses the castability and product design of compacted graphite iron. The introduction of modern measurement and control technologies has made CGI a viable material for high-volume series production. The article describes the production of compacted graphite iron castings and the process control that depends on the production volume of components made from compacted graphite iron. It also discusses the process control for high-volume CGI commonly based on thermal analysis.

According to the ISO 16112 standard for compacted graphite cast irons (CGIs), the graphite particles in CGIs shall be predominantly in the vermicular form when viewed on a two dimensional plane of polish. This article begins with a schematic illustration of compacted graphite microstructures with nodularity. It describes the tensile properties, hardness and compressive properties, and impact properties of CGI. The article concludes with a discussion on the fatigue strength and thermal conductivity of CGI.

This article reviews the graphite morphology, chemical composition requirements, castability, mechanical properties, and corrosion resistance of compacted graphite (CG) irons. It describes the factors affecting the mechanical properties of CG irons. The article also presents the advantages of CG irons.

High-alloy graphitic cast irons are used primarily in applications requiring corrosion resistance or strength and oxidation resistance in high-temperature service. This article describes the properties, applications and heat treatment processes of high-alloy graphitic cast irons, including austenitic gray irons and austenitic ductile irons. It also provides a discussion on the heat treatment of high-silicon irons for heat resisting and corrosion resisting applications.

Metallographic techniques for ductile irons are similar to those for other cast irons but more difficult than for steels, because graphite retention is a challenging task. This article presents recommended procedures to prepare ductile irons. It discusses three contemporary approaches for preparing ductile cast iron specimens with a wide range of phases and constituents as well as variations in graphite morphologies. A wide variety of matrix microstructures can be obtained in ductile irons. Examples are presented using a variety of etchants. Control of the nodularity of graphite in ductile irons is critical to their performance. The article presents details concerning the characterization of the graphite nodules.

This article describes the modification and inoculation of cast iron, and schematically illustrates the major effects of inoculation in gray cast irons. Inoculation could be considered as a common liquid-state treatment for all commercial cast irons (gray/compacted/ductile irons), while modification is essential to produce compacted graphite iron (intermediate level) and ductile iron. The article discusses the most important aspects of a gray cast iron inoculation treatment and the factors influencing its inoculation efficiency. It describes the modification and inoculation of ductile cast iron and compacted graphite cast iron.

This article begins with a description of the classes and grades of ductile iron. It discusses the factors affecting the mechanical properties of ductile iron. The article reviews the hardness properties, tensile properties, shear and torsional properties, compressive properties, fatigue properties, fracture toughness, and physical properties of ductile iron and compares them with other cast irons to aid the designer in materials selection. It concludes with information on austempered ductile iron.

The International Committee of Foundry Technical Associations has identified seven basic categories of casting defects: metallic projections, cavities, discontinuities, defective surfaces, incomplete casting, incorrect dimension, and inclusions or structural anomalies. This article presents some of the common defects in each of the seven categories in a table. It discusses common defects determined during the examination of samples of ductile cast iron in Elkem's research facility in Norway. The article reviews common defects, such as shrinkage cavities, blowholes, hydrogen pinholes, nitrogen defects, and abnormal graphite morphology, found in gray iron. It concludes with a discussion on surface defects in compacted graphite iron.

This article describes a method to predict mechanical properties of cast iron materials and illustrates how to use the predictions in computer-aided tools for the analysis of castings subjected to load. It outlines some ways to predict the hardness and elastic modulus of cast iron without going into dislocation theory. The article discusses modeling of hardness in cast iron based on a regular solution equation in which the properties of each phase depend on chemical composition and coarseness. It describes the evaluation of material parameters from the tensile stress-strain curve. The article concludes with an illustration of a finite-element method (FEM) model containing heterogeneous mechanical properties using local material definitions.

This article discusses the melting and pouring practices, heat treatment, and applications of different types of high-alloy graphitic iron, namely, high-silicon gray irons, high-silicon ductile irons, nickel-alloyed austenitic irons, austenitic gray irons, austenitic ductile irons, and aluminum-alloyed irons.

The mechanical properties of ductile cast irons are determined largely by the microstructure of the steel matrix in combination with the shape, size, and distribution of the graphite nodules. This article describes the designation of ductile cast irons according to the ASTM International designation system and reviews standard-grade ductile cast irons. An overview of the most commonly used standards related to designation and specification of ductile cast iron is presented in a table. This article discusses the use of low-alloy ductile cast irons at elevated temperatures and the chemical compositions and some mechanical properties of austenitic ductile cast irons. The article concludes with a discussion on heat treatment of austempered ductile iron.

During the melting and solidification of cast irons, certain trace (minor) elements may unintentionally accumulate to an extent that they have a detrimental effect on the microstructure of castings. This article discusses the residual elements, trace elements, and tramp elements in cast irons. Elements that influence the matrix structure of cast irons are commonly classified as ferrite-promoting elements or pearlite-promoting elements. The article describes the effects of minor elements on microstructure and properties of cast irons. It discusses the use of a combination of tools to control the effects of minor elements on the structure and properties of cast irons. The article concludes with information on allowable levels of trace and tramp elements in cast irons.

This article discusses the production process, testing methods, quality control, and common defects found in heavy-section ductile iron (DI) castings, along with analyses of industrial examples. The common defects include shrinkage defects, graphite-particle-related defects, and chunk graphite defects. The recommended chemical compositions for certain section thicknesses in ductile iron grades are presented in a table. The article illustrates the relationship between microstructure and mechanical properties of DI by using either industrial examples or castings produced under laboratory conditions.

This article discusses criteria that can be used for the classification of cast iron: fracture aspect, graphite shape, microstructure of the matrix, commercial designation, and mechanical properties. It addresses the main factors of influence on the structure of cast iron, including chemical composition, cooling rate, and heat treatment. The article describes some basic principles of cast iron metallurgy. It discusses the main effects of the chemical composition of ductile iron and compacted graphite (CG) iron. The composition of malleable irons must be selected in such a way as to produce a white as-cast structure and to allow for fast annealing times. Some typical compositions of malleable irons are presented in a table. The article concludes with information on special cast irons.

This article reviews the production stages of iron foundry casting, with particular emphasis on the melting practices, molten metal treatment, and feeding of molten metal into sand molds. It discusses the molten metal treatments for high-silicon gray, high-nickel ductile, and malleable irons. Foundry practices are also described for compacted graphite, high-silicon ductile, and high-alloy white irons.

Cast iron, which usually refers to an in situ composite of stable eutectic graphite in a steel matrix, includes the major classifications of gray iron, ductile iron, compacted graphite iron, malleable iron, and white iron. This article discusses melting, pouring, desulfurization, inoculation, alloying, and melt treatment of these major ferrous alloys as well as carbon and alloy steels. It explains the principles of solidification by describing the iron-carbon phase diagram, and provides a pictorial presentation of the basic microstructures and processing steps for cast irons.