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 describes the use of standardized tests to determine the susceptibility of aluminum alloys to specific forms of corrosion, including pitting, intergranular corrosion, filiform corrosion, exfoliation corrosion, and stress-corrosion cracking.

This chapter describes aluminum applications in aircraft and space vehicles and the special alloys, tempers, and product forms required to meet the unique challenges of flight. It focuses on wrought alloys and products that comprise the bulk of aluminum aircraft structure. The chapter also provides a list of the aerospace alloys and their chemical compositions in common use as well as their application on aircraft.

Forged aluminum products vary widely in their production methods and applications. The forging process allows for control of microstructure and directional properties, and their fatigue and fracture resistance are superior to shape castings. This chapter presents the types, equipment, process steps, alloys, and products of aluminum forging.

This appendix provides fracture toughness and tensile property data for aluminum alloys in the 2000, 6000, 7000, and 8000 series as well as B201 and D357 aluminum castings and powder metal alloys.

Environmentally assisted cracking is a generic term that includes various cracking phenomena such as stress-corrosion cracking (SCC), corrosion fatigue cracking, and liquid-metal embrittlement. This chapter describes these cracking mechanisms beginning with SCC and the factors that influence its formation. It covers alloy selection and mitigation techniques and includes examples of SCC in aircraft components. The chapter also addresses corrosion fatigue, explaining how different environments and operating conditions affect crack propagation, fatigue strength, and fatigue life. It includes information on liquid-metal embrittlement as well.

Aluminum is protected by a barrier oxide film that, if damaged, reforms immediately in most environments. Despite this inherent corrosion resistance, there are conditions where aluminum alloys, like many materials, are subject to the effects of stress-corrosion cracking (SCC). This chapter describes those conditions, focusing initially on the effects of alloying elements and temper on solution potential and how it compares to other metals. It then addresses the issue of intergranular corrosion and its role in SCC. It explains how factors such as stress loads, grain structure, and environment determine whether or not stress-corrosion cracking develops in a susceptible alloy. It also provides stress-corrosion ratings for many alloys, tempers, and product forms and includes information on hydrogen-induced cracking.

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.

Aluminum shapes, rod, bar, tubes, and wire may be produced directly as extrusions or by subsequent processing of continuous cast stock. This chapter describes the key aspects of aluminum extrusion and wire production focusing on the more common hot extrusion process and presenting the general types of aluminum extrusion alloys. An overview of free-machining alloys and products, and weldable 6xxx and 7xxx high-strength structural alloys is also provided.

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.

This chapter describes the ways in which aluminum has been applied to recreation, with special attention on how its usage has changed the nature of these pursuits. It discusses the usage of aluminum in a variety of sports and sport vehicles.

This chapter describes the attributes of aluminum products that are critical for key structural applications. It covers the selection criteria and evaluations performed by the aluminum supplier or customer: physical attributes, mechanical properties (tensile, fracture, and fatigue), and corrosion.

This chapter discusses three related corrosion mechanisms, galvanic, deposition, and stray-current corrosion, explaining why they occur and how they affect the corrosion process. It includes information on testing and prevention methods along with examples of the type of damage associated with these corrosion mechanisms.

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 chapter discusses corrosion prevention methods used with aluminum and its alloys. The methods range from relatively straightforward measures, such as proper handling and storage, to advanced early warning corrosion monitoring systems for military aircraft. The chapter summarizes the basic factors that influence design for corrosion resistance and discusses the use of conversion coatings, organic coatings, porcelain enameling, and electroplating. It also discusses corrosion monitoring methods used in chemical processing and refining industries.

This chapter describes the mechanisms, characteristics, and prevention of intergranular and exfoliation corrosion in various aluminum alloys. It discusses susceptible alloys and recommended tempers and presents several examples of exfoliation in aircraft components. It also explains how the two forms of corrosion are related to stress-corrosion cracking.

The term heat treatable alloys is used in reference to alloys that can be hardened by heat treatment, and this chapter briefly describes the major types of heat treatable nonferrous alloys. The discussion provides a general description of annealing cold-worked metals and describes some of the common nonferrous alloys that can be hardened through heat treatment. The nonferrous alloys covered include aluminum alloys, cobalt alloys, copper alloys, magnesium alloys, nickel alloys, and titanium alloys.

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.