Aluminum casting alloys are the most versatile of all common foundry alloys and generally have the highest castability ratings. This article provides an overview of the common methods of aluminum shape casting. These include gravity casting, die casting, sand casting, lost foam casting, shell mold casting, plaster casting, investment casting, permanent mold casting, squeeze casting, semisolid forming, centrifugal casting, and pressure die casting. The article presents several different factors on which the selection of a casting process depends. It discusses gating and risering principles in casting. The article concludes with information on premium engineered castings that provide higher levels of quality and reliability than in conventionally produced castings.

Sand mold and permanent mold castings 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 the 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 the melting furnaces used in direct arc melting, induction melting, and boiling. The article describes the sand casting and permanent mold casting of steel. The process design and castings of thin sections are also discussed.

The term shape memory alloys (SMAs) refers to the group of metallic materials that demonstrate the ability to return to some previously defined shape or size when subjected to the appropriate thermal procedure. Materials that exhibit shape memory only upon heating are referred to as having a one-way shape memory. Some materials also undergo a change in shape upon recooling. These materials have a two-way shape memory. This article discusses the general characteristics of SMAs by using typical transformation versus temperature curve. It describes the processing, applications and properties (mechanical and physical) of commercial SMA alloys, namely nickel-titanium alloys and copper-base alloys.

This article focuses on the specific aspects of nitinol that are of interest to medical device designers. It describes the physical metallurgy, physical properties, and tensile properties of the nitinol. The article discusses the factors influencing superelastic shape memory effects, fatigue, and corrosion in medical device design. It reviews the biocompatibility of nitinol based on corrosion behavior. The article describes the general principles, potential pitfalls, and key properties for manufacturing, heat treatment, and processing of nitinol.

The primary objectives of the rolling process are to reduce the cross section of the incoming material while improving its properties and to obtain the desired section at the exit from the rolls. This article illustrates a rolling sequence for the fabrication of bars, shapes, and flat products from blooms, billets, and slabs. It describes two methods for shapes or sections: universal rolling and caliber rolling. The article provides information on two-high mills and three-high mills. Specialty mills for thin sheets, namely, the Sendzimir mill and planetary mill, are discussed. The article analyzes the components of a computer controlled system for high-speed mills. Steels and nonferrous materials are also discussed. The article concludes with information on the defects in flat, bar, or shaped products due to heating and rolling practices.

Understanding fatigue crack growth is critical for the safe operation of many structural components. This article reviews the standard fracture mechanics and methods to determine the crack growth rate for a material and loading condition experimentally. It also addresses the two most important aspects of crack-growth modeling: loading environment and crack geometry.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of wrought aluminum alloys and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the corrosion-fatigue fracture, fatigue striations, tension-overload fracture surface, ductile fracture, cone-shaped fracture surface, intergranular crack propagation, transgranular crack propagation, stress-corrosion cracking, hydrogen damage, and grain-boundary separation of these alloys. Fractographs are also provided for a forged aircraft main-landing gear wheel and actuator beam, an aircraft wing spar, a fractured aircraft propeller blade, shot peened fillet, an aircraft lower-bulkhead cap, and clevis-attachment lugs.

Dimensional and shape changes caused by heat treatment have been the subject of scientific and industrial research for a very long time. This article provides an overview of the complexity of distortion and stress generation during heat treatment of steels. It discusses the measurement and evaluation of dimensional and shape changes with examples. The article describes the mechanisms at work during the generation of stresses and distortion during heat treatment. A hypothetical experiment with increasing application to real life is used to develop a systematization of unavoidable size and shape changes. The article also provides information on the carriers of distortion potential that cause measureable size and shape changes.

Ceramics usually require some form of machining prior to use to meet dimensional and surface quality standards. This article focuses on abrasive machining, particularly grinding, and addresses common methods and critical process factors. It covers cylindrical, centerless, and disk grinding and provides information on tooling, wheel selection, work material, and operational factors. It also discusses precision slicing and slotting, lapping, honing, and polishing as well as abrasive waterjet, electrical discharge, laser, and ultrasonic machining.

A cylindrical specimen compressed with friction at the die surfaces does not remain cylindrical in shape but becomes bulged or barreled. Tensile stresses associated with the bulging surface make the upset test a candidate for workability testing. This article discusses test-specimen geometry and friction conditions; strain measurements; crack detection; and material inhomogeneities, which are to be considered for performing cold upset testing. It describes test characteristics in terms of deformation, free-surface strains, and stress states for performing cylindrical compression tests. The article illustrates the fracture loci in cylindrical, tapered, and flanged upset-test specimens of aluminum alloy and type 1045 cold-finished steel.

Shell molding is used for making production quantities of castings that range in weight from a few ounces to approximately 180 kg (400 lb), in both ferrous and nonferrous metals. This article lists the limitations or disadvantages of shell mold casting. It describes the two methods for preparation of resin-sand mixture for shell molding, namely, mixing resin and sand according to conventional dry mixing techniques, and coating the sand with resin. Shaping of shell molds and cores from resin sand mixtures is accomplished in machines. The article discusses the major steps in producing a mold or core and describes the problems most frequently encountered in shell-mold casting. The problems include mold cracking, soft molds, low hot tensile strength of molds, peelback, and mold shift. The article concludes with information on examples that provide some relative cost comparisons between shell molding and green sand molding.

The potential for introducing defects during processing becomes greater as the relative density of pressed and sintered powder metallurgy (PM) parts increases and more multilevel parts with complex geometric shapes are produced. This article discusses the potential defects in pressed and sintered PM parts: density variations, compaction and ejection cracks, microlaminations, poor degree of sintering, and voids from prior lubricant agglomerates. It describes the various methods applicable to green compacts: direct-current resistivity testing, radiographic techniques, computed tomography, and gamma-ray density determination. The article also discusses the methods for automated nondestructive testing of pressed and sintered PM parts: acoustic methods-resonance testing, eddy current testing, magnetic bridge comparator testing, ultrasonic techniques, radiographic techniques, gamma-ray density determination, and visual inspection.