This appendix provides information on temper designations for strain-hardened aluminum, heat treatable aluminum alloys, and annealed aluminum products.

This article discusses the composition, structures, properties, and behaviors of aluminum alloys and explains how they correspond to specific alloying elements. It begins with an overview of the general characteristics of wrought and cast aluminum alloys, the four-digit classification system by which they are defined, and the applications for which they are suited. It then explains how primary alloying elements, second-phase constituents, and impurities affect yield strength, phase formation, and grain size and how they induce structural changes that help refine certain alloys. The article also explains how primary alloying elements affect corrosion and wear behaviors and how they influence fabrication processes such as forming, forging, welding, brazing, and soldering.

This appendix contains composition limit data for wrought aluminum and aluminum alloys.

This appendix includes composition limit data for aluminum castings and ingots.

This introduction presents an overview of the discovery of aluminum, the origins of the aluminum industry, and the evolution of the industry.

Casting is one of the most economical manufacturing processes for providing shape to components of machinery and is used in a wide range of industries. This chapter is a brief account of the advantages, applications, limitations, and market growth of aluminum casting. It also provides information on the process of conversion of steel and iron parts to aluminum.

This chapter discusses the development of aluminum, its industry growth, and its modern uses in manufacturing. It begins with the biography of Charles Martin Hall, who invented the process for reducing aluminum from its ore. The evolution of aluminum production from the Pittsburgh Reduction Company to a pilot plant on Smallman Street in Pittsburgh, to a production plant in New Kensington, and to Niagara Falls, New York, is then described. This is followed by a discussion on early aluminum applications and the usage of lower-cost raw materials. The chapter provides information on aluminum production process integrated by Aluminum Company of America (Alcoa) and the numerous technical problems and solutions related to Alcoa's research from World War I to World War II. The aerospace applications for aluminum alloys are also presented. The chapter concludes with a section on aluminum alloys developed by Alcoa.

This chapter describes the effects of metallurgical variables on the corrosion of aluminum alloys. Emphasis is placed on the effect of constituent particles on pitting corrosion of aluminum.

This chapter addresses the general effects of composition, mechanical treatment, surface treatment, processing, and fabrication operations on the corrosion resistance of aluminum and its alloys. Different types of surface treatments covered include claddings, anodizing, and conversion coatings. The processing steps that can have relatively significant impact on corrosion resistance are homogenization, rolling, extrusion, quenching, aging, and annealing.

Aluminum has many outstanding properties, leading it to be used for a wide range of applications. It offers excellent strength-to-weight ratio, good corrosion and oxidation resistance, high electrical and thermal conductivity, exceptional formability, and relatively low cost. This chapter examines the metallurgy, composition, processing, and mechanical properties of aluminum and its alloys, both cast and wrought forms. It also covers heat treating and basic temper designations, including annealed, work hardened, solution heat treated, and solution heated treated and aged. The chapter concludes with information on corrosion and oxidation resistance.

Porosity in aluminum is caused by the precipitation of hydrogen from liquid solution or by shrinkage during solidification, and more usually by a combination of these effects. Nonmetallic inclusions entrained before solidification influence porosity formation and mechanical properties. This chapter describes the causes and control of porosity and inclusions in aluminum castings as well as the combined effects of hydrogen, shrinkage, and inclusions on the properties of aluminum alloys. In addition, it discusses the applications of radiography to reveal internal discontinuities in aluminum.

This chapter provides guidelines on how to set up and run an effective quality-improvement program for aluminum extrusion operations. It begins by identifying production processes and variables that impact the quality of hard and soft alloy extrusions. It then presents a series of checklists and flowcharts that can be used to monitor and troubleshoot billet-making and extrusion processes, die construction, equipment maintenance, heat treating, and sawing and stretching procedures. It also discusses the importance of charting test results and monitoring surface treatments that may be required to improve corrosion, oxidation, or wear resistance.

Aluminum generally has excellent resistance to corrosion and gives years of maintenance-free service in natural atmospheres, fresh waters, seawater, many soils and chemicals, and most foods. This chapter explains why aluminum and aluminum alloys are naturally resistant to corrosion and describes the conditions and circumstances under which their natural defenses break down. It discusses the causes and forms of corrosion observed in aluminum alloys and the effect of composition, microstructure, processing history, and environmental variables such as impurities, fluid flow, surface area, pressure, and temperature.

This chapter serves as a study and guide on the main phase constituents of cast aluminum-silicon alloys, alpha-Al solid solution and Si crystals. The first section focuses on the structure of Al-Si castings in the as-cast state, covering the morphology of the alpha-Al solid solution grains and the process by which they form. It describes how cooling rates, temperature gradients, and local concentrations influence the topology of the crystallization front, and how they play a role in determining the morphology and dispersion degree of the grains observed in cross sections of cast parts. It also describes the mechanism behind dendritic grain crystallization and how factors such as surface tension, capillary length, and lattice symmetry affect dendritic arm size and spacing. The section that follows examines the morphology of the silicon crystals that form in aluminum-silicon castings and its effect on properties and processing characteristics. It discusses the faceted nature of primary Si crystals and the modification techniques used to optimize their shape. It also describes the morphology of the (alpha-Al + Si) eutectic, which can be lamellar or rodlike in shape, and explains how it can be modified through temperature control or alloy additions to improve properties such as tensile strength and plasticity and reduce shrinkage.

Structurally differentiated intermetallic phases are important constituents in the microstructure of aluminum alloys, with the potential to influence properties, behaviors, and processing characteristics. These phases can form in aluminum-silicon alloys with transition metals (Fe, Mn, Ni, Cr, V, Ti) and with metals such as Mg and Cu. This chapter is a compilation of phase diagrams, microstructure images, and tables, providing information on more than 30 binary, ternary, and quaternary alloy systems associated with intermetallic phases in aluminum-silicon castings. Each section includes tabular information and data on the intermetallic phases in the aluminum corner of the equilibrium phase diagram, the characteristics of the crystal lattice of intermetallic phases, the chemical composition of the alloy intermetallic phases, and equilibrium reactions in the alloy system.

This chapter is an atlas of microstructures observed in AlSi7Mg, AlSi11, and Al21CuNiMg modified with either eutectic (strontium, sodium) or hypereutectic (phosphorus) silicon crystals. The microstructure images reveal the as-cast state of gravity castings made in sand and metal molds, before and after modification. The chapter also provides composition data and includes callouts identifying various phase constituents in the interdendritic eutectic microstructure.

This chapter provides basic engineering information on aluminum alloys with an emphasis on their use in applications where weight is a significant design factor. It discusses the advantages and limitations of various types of aluminum along with their compositions, designations, and achievable strengths. It explains how some alloys are hardened through solution strengthening and cold working, while others are strengthened by precipitation hardening. It also describes production and fabrication processes such as melting, casting, rolling, forging, forming, extruding, heat treating, and joining, and includes a section on the causes and effects of corrosion and how they are typically controlled.