The 391-type hypereutectic aluminum-silicon alloys are hypereutectic alloys designed for applications where excellent wear resistance is needed. They are similar to the 390 family of alloys, except for a low copper content to improve castability and corrosion resistance. This datasheet provides information on key alloy metallurgy and processing effects on mechanical properties of separately cast test bars of these alloys.

Aluminum casting alloys are among the most versatile of all common foundry alloys and generally have high castability ratings. This article provides an overview of the common methods of aluminum shape casting. It discusses the designations of aluminum casting alloys categorized by the Aluminum Association designation system. The article summarizes the basic composition groupings of aluminum casting alloy and discusses the effects of specific alloying elements and impurities. The characteristics of the important casting processes are summarized and compared in a table. The article presents the advantages and disadvantages of green sand casting, permanent mold casting, semipermanent mold casting, and high-pressure die casting. A discussion on other casting processes, such as investment casting, lost foam, plaster mold casting, pressure casting, centrifugal casting, and semisolid casting, is also included.

Castability is a complex characteristic that depends on both the intrinsic fluid properties of the molten metal and the manner in which the particular alloy solidifies. This article discusses the practical aspects of solidification important to aluminum foundrymen. The primary focus is on the chemical segregation that occurs during freezing, because it determines the castability of the alloy. The article describes the two types of segregation, namely, microsegregation and macrosegregation. It discusses the effect of freezing range on castability of an alloy. The article lists the freezing range of a number of important alloys. It concludes with a discussion on castability of 2xx, 3xx, 4xx, 5xx, and 7xx alloys.

The strength of aluminum castings can be improved significantly by heat treatments, which control the size, shape, and distribution of the impurity elements in the casting. This article presents a discussion on the heat treatment of aluminum alloy castings, with a focus on the fundamental technical aspects involved in each process step. The intent is to convey a good understanding of the fundamental aspects of heat treatment. Typical heat treatments of aluminum casting alloys are presented in a table. The article describes the solution heat treatment, quenching, and preaging of Al-Si-Mg alloys, as well as the solution heat treatment and artificial aging of Al-Si-Cu-Mg casting alloys.

Foundry practices critical to the production of cast irons include melting, alloying, molten metal treatment, pouring, and the design of feeding systems (gating and risering) to allow proper filling of the casting mold. This article reviews these 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 castability factors, such as fluidity, shrinkage, and resistance, of gray iron. Typical cupola charge compositions and the final analyses for class 30 and class 40 gray iron castings are presented in a table. The article describes the induction melting and arc furnace melting used in gray iron foundries. It also reviews the inoculation methods such as stream inoculation and mold inoculation, of gray iron.

This article discusses some of the factors that are linked directly to the casting design of ductile iron castings. It reviews the choice of molding process, application of draft, and patternmaker's allowance that should be taken into consideration in designing castings. The article describes the solidification shrinkage associated with the volume change that occurs during solidification, as well as strength and stiffness of ductile iron castings. It concludes with a discussion on the thermal deformation and residual stress in ductile iron castings.

Castability of alloys is a measure of their ability to be cast to a given shape with a given process without the formation of cracks/tears, pores/shrinkage, and/or other significant casting defects. This article discusses the factors which affect the fluidity of an iron melt: alloy composition and initial melt condition. Besides the basic alloy properties, the effective castability of high-alloy irons can be significantly improved through casting and casting system design. The article describes the product design and processing factors of high-alloy graphitic irons and high-alloy white irons. It explains the heat treatment of high-silicon irons for high-temperature service and concludes with a discussion on machining and finishing of high-alloy iron castings.

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.

This article begins with an overview of classes and applications of gray iron. It discusses the castability of gray iron in terms of section sensitivity and fluidity. The article provides information on the dimensions of prevailing sections recommended for gray irons and reviews the properties and specifications of test bar. Properties of gray iron, such as fatigue limit, pressure tightness, impact resistance, machinability, and dimensional stability, at both room and elevated temperature, are reviewed. Wear behavior of gray iron castings during sliding contact under conditions of normal lubrication is also discussed. The article evaluates the use of alloys and heat treatment to modify as-cast properties. It concludes with information on the physical properties of gray iron castings.

Castability of alloys is a measure of their ability to be cast to a given shape with a given process without the formation of casting defects. This article describes the factors that limit fluidity as well as experimental methods for measuring fluidity of various alloys. Various tests designed for measuring the hot tearing tendency in alloys are discussed. The article also discusses the temperature dependence, criteria, and modeling of hot tearing.

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.

Sand mold and permanent mold casting are the major methods for shape casting of steels, with production closely split among green sand, chemically bonded sand, and permanent mold processes. This article describes key aspects of the steel casting process, including steel solidification characteristics, melting practices, melt treatment, and feeding of the molten steel into the mold used in steel foundries. It discusses the features of melting furnaces used in direct arc melting and induction melting. It reviews factors such as wall thickness and designing for avoidance of hot spots. The article explains the sand casting and permanent mold casting of steel. The process design and casting of thin sections are also discussed.

This article discusses the physical metallurgy of cast cobalt alloys with an emphasis on the crystallography, compositions, phases and microstructure, and properties. Cobalt alloys are cast by several different foundry methods. The article describes the argon-oxygen decarburization and continuous casting process. It provides information on castability and quality of the casted alloys. The article details the postcasting treatment, including heat treatment, hot isostatic pressing, and coatings. It summarizes the applications of cast cobalt alloys.

Copper alloy castings are used in applications that require superior corrosion resistance, high thermal or electrical conductivity, good bearing surface qualities, or other special properties. Discussing the types and compositions of copper alloy used for casting, this article describes the major factors considered in alloy selection for casting, including raw material cost, castability, machinability, and the bearing and wear properties. It also provides information on the cost of the final product.

The selection of the best material for a particular design is intimately associated with the decisions of how to process the material or manufacture a part. This article describes the basic characteristics of manufacturing processes such as material factors, shape factors, and process factors. The influence of materials on the manufacturing cost is described with a specific example. The article discusses the design for manufacturability to minimize the total number of parts, use readily processed materials, and eliminate machining and finishing operations. It reviews the factors influencing the selection of a material for production, including material composition, heat-treated condition, surface finish, and cost of material. The article describes the material characteristics, such as terms formability, workability, castability, machinability, and weldability, that aid or hinder the production of a part without defects.

ASTM specification A 48 classifies gray irons in terms of tensile strength. The usual microstructure of gray iron is a matrix of pearlite with graphite flakes dispersed throughout. Section sensitivity effects are used in the form of a wedge test in production control to judge the suitability of an iron for pouring a particular casting. Mechanical property values obtained from test bars are sometimes the only available guides to the mechanical properties of the metal in production castings. Gray iron castings are used widely in pressure applications such as cylinder blocks, manifolds, pipe and pipe fittings, compressors, and pumps. Where high impact resistance is needed, gray iron is not recommended. The machinability of most gray cast iron is superior to that of most other cast irons of equivalent hardness, as well as to that of virtually all steel. Gray iron is used widely for machine components that must resist wear.

Directionally solidified (DS) and single-crystal (SX) superalloys and process technology are contributing to significant advances in turbine engine efficiency and durability. These gains are expected to arise from the development of higher creep strength and improved oxidation-resistant SX alloy compositions as well as from the development of SX casting and fabrication technology to utilize advanced transpiration-cooling schemes. This article provides a detailed discussion on the chemistry and castability of first- and second-generation DS and SX superalloys. It summarizes the chemistry modifications applied to MAR-M 247 to develop CMSX-2 with respect to function and objectives. The article also lists the nominal compositions of first- and second-generation DS and SX superalloys.

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.

Copper alloy castings are used in applications that require superior corrosion resistance, high thermal or electrical conductivity, good bearing surface qualities, or other special properties. This article discusses the nominal composition and mechanical properties of copper casting alloys, designated in the Unified Numbering System. It also describes the selection factors of copper casting alloys, including castability, machinability, dimensional tolerances, bearing and wear properties, and cost considerations. The article provides information on the relative corrosion resistance of 14 different classes of copper casting alloys in a wide variety of liquids and gases which helps in selecting alloys for corrosion service.