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 covers the corrosion behavior of beryllium in aqueous environments. It describes the chemical reactions that drive the corrosion process, the conditions required for equilibrium, and the factors that affect corrosion resistance. It discusses the stability of the native oxides that form on the surface of beryllium and their ability to withstand acids, bases, and corrosive agents found in rain and seawater. It explains how carbides, inclusions, ions, and impurities contribute to corrosion damage, particularly pitting, and how corrosion reduces the ductility and fracture strength of certain beryllium alloys.

This chapter discusses the principles of corrosion of metals in aqueous environments. The thermodynamics of aqueous corrosion is the subject of the first half of this chapter, which addresses concepts such as corrosion reactions and free-energy change, the relationship between free energy and electrochemical potential, the effect of ionic concentration on electrode potential, and the corrosion behavior of a metal based on its potential-pH diagram. The corrosion (potential-pH) behavior of iron, gold, copper, zinc, aluminum, and titanium are described. Understanding the kinetics of corrosion and the factors that control the rates of corrosion reactions requires examination of the concepts of polarization behavior and identification of the various forms of polarization in an electrochemical cell. These concepts, addressed in the remaining of this chapter, include anodic and cathodic reactions, the mixed-potential theory, and the exchange currents.

This chapter discusses the formation and control of aqueous corrosion in iron and steel. It also provides information on passivation, stress corrosion, rust, and direct oxidation.

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.

Nickel-base alloys used for low-temperature aqueous corrosion are commonly referred to as corrosion-resistant alloys (CRAs), and nickel alloys used for high-temperature applications are known as heat-resistant alloys, high-temperature alloys, or superalloys. The emphasis in this chapter is on the CRAs and in particular nickel-chromium-molybdenum alloys. The chapter provides a basic understanding of general welding considerations and describes the welding metallurgy of molybdenum-containing CRAs and of nickel-copper, nickel-chromium, and nickel-chromium-iron CRAs. It discusses the corrosion behavior of nickel-molybdenum alloys and nickel-chromium-molybdenum alloys. Information on the phase stability and corrosion behavior of nickel-base alloys is also included.

This chapter familiarizes readers with the basic concepts of corrosion, discussing chemical reactions, ion transfer mechanisms, electrochemical processes and variables, and the formation of solid corrosion products. It presents a simple but effective teaching tool, the elementary electrochemical corrosion circuit, using it to explain how electric potential differences drive the corrosion process and how corrosion rates vary in proportion to current density. The chapter concludes with a discussion on the importance of corrosion products, such as oxides and hydroxides, and how their formation can be a major factor in controlling corrosion.

This chapter addresses the basic concepts important to understanding corrosion of metals. It begins with an overview of the three types of behaviors that a metal exhibits when immersed in an environment and of the four requirements of a corrosion cell. The chapter then covers the important characteristics of metals with respect to corrosion, namely the metallurgical characteristics, the inherent tendency to corrode, and the tendency to form insoluble corrosion products. The important characteristics of aqueous solutions with respect to corrosion are then addressed. The characteristics include: conductivity of the solution, acidity and alkalinity, oxidizing power, degree of ionization, and solubility in the solution. These characteristics, in combination with the characteristics of the metal, will determine the corrosion behavior of a metal/environment combination. The chapter concludes with a section on the determination of corrosion rates and corrosion rate allowances.

This chapter addresses the issue of stress-corrosion cracking (SCC) in carbon and low-alloy steels. It discusses crack initiation, propagation, and fracture in aqueous chloride, hydrogen sulfide, sulfuric acid, hydroxide, ammonia, nitrate, ethanol, methanol, and hydrogen gas environments. It explains how composition and microstructure influence SCC, as do mechanical properties such as strength and fracture toughness and processes such as welding and cold work. It also discusses the role of materials selection and best practices for welding.

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 explores the behavior of stainless steel in media that promote corrosion. The forms of corrosion covered are uniform corrosion, atmospheric corrosion, localized corrosion, pitting corrosion, crevice corrosion, and grain boundary corrosion. The chapter discusses the influence of material and environmental variables on stress-corrosion cracking (SCC) and the mechanisms proposed for SCC in stainless steel, comparing the mechanism of SCC with hydrogen embrittlement. In addition, it provides information on biocorrosion and microbiologically induced corrosion in ambient aqueous environments.

This chapter discusses the effects of metallurgical variables on dealloying corrosion. It begins by describing the processes involved in dealloying of metal alloys in aqueous environments. This is followed by a discussion on the morphology of porous dealloyed structures below and above the critical potential. Some features experimentally observed for dealloying systems are then considered. The chapter concludes by briefly reviewing the proposed mechanisms for the formation of porous metals, namely ionization-redeposition mechanism, surface diffusion mechanism, volume diffusion mechanism, and percolation model of selective dissolution.

This chapter focuses on stress-corrosion cracking (SCC) of metals and their alloys. It is intended to familiarize the reader with the phenomenological and mechanistic aspects of stress corrosion. The phenomenological description of crack initiation and propagation describes well-established experimental evidence and observations of stress corrosion, while the discussions on mechanisms describe the physical process involved in crack initiation and propagation. Several parameters that are known to influence the rate of crack growth in aqueous solutions are presented, along with important fracture features.

This chapter describes various units and process streams that are often susceptible corrosion inhibitors in crude oil refineries, discusses the types and applications of corrosion inhibitors, and provides some information on corrosion monitoring techniques used at refineries.

This appendix is a comprehensive collection of selected sources related to corrosion properties of materials and corrosion testing.

This chapter presents the primary considerations and mechanisms for corrosion and how they are involved in the selection of materials for process equipment in petroleum refineries and petrochemical plants. In addition, specific information on mechanical properties, corrosion, sulfide stress cracking, hydrogen-induced cracking, stress-oriented hydrogen-induced cracking, hydrogen embrittlement cracking, stress-corrosion cracking, velocity-accelerated corrosion, erosion-corrosion, and corrosion control is provided.

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.

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.

All materials are susceptible to corrosion or some form of environmental degradation. Although no single material is suitable for all applications, usually there are a variety of materials that will perform satisfactorily in a given environment. The intent of this chapter is to review the corrosion behavior of the major classes of metals and alloys as well as some nonmetallic materials, describe typical corrosion applications, and present some unique weaknesses of various types of materials. It also aims to point out some unique material characteristics that may be important in material selection, and discuss, where appropriate, the characteristic forms of corrosion that attack specific materials. The materials addressed in this chapter include carbon steels, weathering steels, and alloy steels; nickel, copper, aluminum, titanium, lead, magnesium, tin, zirconium, tantalum, niobium, and cobalt and their alloys; polymers; and other nonmetallic materials, including rubber, carbon and graphite, and woods.