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.

Corrosion problems can be divided into eight categories based on the appearance of the corrosion damage or the mechanism of attack: uniform or general corrosion; pitting corrosion; crevice corrosion, including corrosion under tubercles or deposits, filiform corrosion, and poultice corrosion; galvanic corrosion; erosion-corrosion, including cavitation erosion and fretting corrosion; intergranular corrosion, including sensitization and exfoliation; dealloying; environmentally assisted cracking, including stress-corrosion cracking, corrosion fatigue, and hydrogen damage (including hydrogen embrittlement, hydrogen-induced blistering, high-temperature hydrogen attack, and hydride formation). All these forms are addressed in this chapter in the context of aqueous corrosion. For each form, a general description is provided along with information on the causes and the list of metals that can be affected, with particular emphasis on the recognition and prevention measures.

Corrosion can be defined as a chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties. This chapter describes the effects and economic impact of corrosion in major industrial plants. The emphasis in this chapter, as well as in other chapters in this book, is on aqueous corrosion, or corrosion in environments where water is present. The chapter describes the classification of various forms of corrosion based on the nature of the corrodent, mechanism of corrosion, and appearance of the corroded metal. It discusses five primary methods of corrosion control, namely, material selection, coatings, inhibitors, cathodic protection, and design. Examples of the opportunities in corrosion control and the means to implement a program to capitalize on those opportunities are presented in a table. The chapter concludes with varied sources of information pertaining to corrosion and corrosion prevention.

This chapter discusses the ambient-temperature corrosion characteristics of aluminum metal-matrix composites (MMCs), including composites formed with boron, graphite, silicon carbide, aluminum oxide, and mica. It also discusses the effect of stress-corrosion cracking on graphite-aluminum composites and the use of protective coatings and design criteria for corrosion prevention.

This chapter discusses common forms of corrosion, including uniform corrosion, galvanic corrosion, pitting, crevice corrosion, dealloying corrosion, intergranular corrosion, and exfoliation. It describes the factors that contribute to stress-corrosion cracking, hydrogen embrittlement, and corrosion fatigue and compares and contrasts their effects on mechanical properties, performance, and operating life. It also includes information on high-temperature oxidation and corrosion prevention techniques.

Pitting is the most common corrosion attack on aluminum alloy products. This chapter explains why pitting occurs and how it appears in different types of aluminum. It discusses pitting rates, pitting potentials, and pitting resistance as well as testing and prevention methods. It also discusses the problem of crevice corrosion and how it is influenced by crevice geometry and operating environment. The discussion covers the most common forms of crevice corrosion, including water staining, poultice corrosion, and filiform corrosion, along with related testing and prevention methods.

This chapter is a detailed account of major sources of stray current that can cause corrosion and discusses several ways to prevent damage from stray-current corrosion.

Corrosion is a key subject for more or less all classes of alloys that fall within the broad definition of stainless steels because these alloys were developed with the intention of preventing corrosion. This chapter provides an introduction to the fundamentals of electrochemical theory as it pertains to corrosion resistance of stainless steels. The discussion provides an overview of electrochemical reactions, Faraday's law, the Nernst equation, galvanic versus electrochemical cells, corrosion tendency, and Pourbaix diagrams.

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 chapter discusses the most common causes and contributing factors for external corrosion and stress-corrosion cracking on oil and natural gas pipelines, as well as describes procedures for prevention, mitigation, detection, assessment, and repair. The forms of external corrosion covered include differential cell corrosion, microbiologically influenced corrosion, and stray current corrosion.

This chapter outlines the major types of corrosion, their interactions, their complicating effects on fracture and wear, and some possible prevention methods. The types of corrosion considered in the chapter are galvanic corrosion, uniform corrosion, pitting corrosion, crevice corrosion, microbiologically influenced corrosion, stress-corrosion cracking, and corrosion fatigue.

This chapter focuses on the effects of microscopic organisms and the by-products they produce on the electrochemical corrosion of metals. It begins by considering the characteristics of organisms that allow them to interact with the corrosion processes, the mechanisms by which organisms can influence the occurrence or rate of corrosion, and the types of corrosion most often influenced by microbes. The chapter then discusses the formation of biofilms on the surface of metals. This is followed by a list of industries most often reported as being affected by microbiological corrosion, along with the organisms usually implicated in the attack. The types of attack that have most commonly been documented are illustrated through generalized case histories for different classes of alloys. The chapter also describes the general approaches to be taken to prevent microbiologically influenced corrosion. It ends with some information on the inhibition of corrosion by the action of bacteria.

Stress-corrosion cracking (SCC) in magnesium alloys was first reported in the 1930s and, within ten years, became the focus of intense study. This chapter provides a summary of all known work published since then on the nature of SCC in magnesium alloys and how it is related to composition, microstructure, and heat treatment. It describes the types of environments where magnesium alloys are most susceptible to SCC and the effect of contributing factors such as temperature, strain rate, and applied and residual stresses. The chapter also discusses crack morphology and what it reveals, provides information on proposed cracking mechanisms, and presents a practical approach for preventing SCC.

Titanium alloys are generally resistant to stress-corrosion cracking (SCC), but under certain conditions, the potential for problems exists. This chapter identifies the types of service environments where titanium alloys have exhibited signs of SCC. It begins by describing the nominal composition, designation, and grade of nearly two dozen commercial titanium alloys and the different types of media (including oxidizers, organic compounds, hot salt, and liquid metal) in which SCC has been observed. It discusses the mechanical and metallurgical factors that influence SCC behavior and examines the cracking and fracture mechanisms that appear to be involved. The chapter also includes information on SCC test standards and provides detailed guidelines on how to prevent or mitigate the effects of SCC.

Although zirconium resists stress-corrosion cracking (SCC) where many alloys fail, it is susceptible in Fe3+- and Cu2+-containing solutions, concentrated HNO3, halogen vapors, mercury, cesium, and CH3OH + halides. This chapter explains how composition, texture, stress levels, and strain rate affect the SCC behavior of zirconium and its alloys. It describes environments known to induce SCC, including aqueous solutions, organic liquids, hot and fused salts, and liquid metals. It also discusses cracking mechanisms and SCC prevention and control techniques.

This chapter provides a detailed account of crevice corrosion of metals. It begins by describing various critical factors influencing crevice corrosion. This is followed by a section presenting selected examples of crevice corrosion of stainless steel, nickel alloys, aluminum alloys, and titanium alloys in different environments. Methods that have been developed for differentiating and ranking the resistance of alloys toward crevice corrosion are then reviewed. The chapter concludes by discussing various strategies for the prevention of crevice corrosion, namely design awareness, use of inhibitors, and potential control methods.

This chapter outlines the step-by-step processes by which materials are selected in order to prevent or control corrosion and includes information on materials that are resistant to the various forms of corrosion. The various forms of corrosion covered are general (uniform) corrosion, localized corrosion, galvanic corrosion, intergranular corrosion, stress-corrosion cracking, hydrogen damage, and erosion-corrosion. In addition, the economic importance of cost-effective materials selection is also considered.

Corrosion can be defined as a chemical or electrochemical reaction between a material and its environment that causes the material and its properties to degrade. In most cases, it refers to the electrochemical oxidation of metals accompanied by the production of oxides or salts of the base material. This chapter discusses the process of corrosion and how to prevent or mitigate its effects. It describes several forms of corrosion, including uniform, intergranular, pitting, crevice, and stray-current corrosion, and the effects of stress-corrosion cracking, corrosion fatigue, and selective leaching. It discusses the use of corrosion inhibitors, cathodic and anodic protection, pH control, and Pourbaix diagrams.

This chapter reviews weld corrosion in three key application areas: petroleum refining and petrochemical operations, boiling water reactor piping systems, and components used in pulp and paper plants. The discussion of each area addresses general design and service characteristics, types of weld corrosion issues, and prevention or mitigation strategies.

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.