This chapter discusses the erosion and erosion-corrosion behaviors of metals and alloys. It includes data primarily related to particle-laden gas streams impacting on the metal surface. It also covers properties and applications and provides guidelines for materials selection.

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.

This chapter discusses five forms of mechanically assisted degradation of metals: erosion, fretting, fretting fatigue, cavitation and water drop impingement, and corrosion fatigue. Emphasis is placed on the mechanisms and the factors affecting these forms of degradation.

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 covers common types of erosion, including droplet, slurry, cavitation, liquid impingement, gas flow, and solid particle erosion, and major types of wear, including abrasive, adhesive, lubricated, rolling, and impact wear. It also covers special cases such as galling, fretting, scuffing, and spalling and introduces the concepts of tribocorrosion and biotribology.

Glasses and ceramics are susceptible to stress-corrosion cracking (SCC), as are metals, but the underlying mechanisms differ in many ways. One of the major differences stems from the lack of active dislocation motion that, in metals, serves to arrest cracks by reducing stress concentrations at flaw tips. As a result, even relatively small flaws (20 to 50 μm in radius) can cause glasses and ceramics to fail. This chapter examines the propensity of flaws to grow in glass and ceramic materials exposed to different environments, especially water, at stresses well below those that would produce immediate failure. It describes crack growth mechanisms, explains how to measure crack growth rates and predict time to failure, and provides crack growth data for a number of materials and environments.

This chapter discusses the conditions and sequence of events that lead to stress-corrosion cracking (SCC) and the mechanisms by which it progresses. It explains that the stresses involved in SCC are relatively small and, in most cases, work in combination with the development of a surface film. It describes bulk and surface reactions that contribute to SCC, including dissolution, mass transport, absorption, diffusion, and embrittlement, and their role in crack nucleation and growth. It also discusses crack tip chemistry, grain-boundary interactions, and the effect of stress-intensity on crack propagation rates, and describes several mechanical fracture models, including corrosion tunnel, film-induced cleavage, and tarnish rupture models.

This chapter explains how mechanical processes, including erosion, cavitation, impingement, and fretting, contribute to the effects of corrosion in aluminum alloys. It describes the two main types of erosion-corrosion and the factors involved in cavitation and liquid impingement erosion along with testing and prevention methods. It also provides information on fretting corrosion and fretting fatigue.

This chapter examines methods of internal corrosion prediction for multiphase pipelines and details methodologies to perform internal corrosion direct assessment for natural gas pipelines. Further, real-time monitoring techniques for assessing actual corrosion at critical locations are discussed.

Combustion byproducts such as soot, ash, and abrasive particulates can inflict significant damage to boiler tubes through the cumulative effect of erosion. This chapter examines the types of erosion that occur on the fire side of boiler components and the associated causes. It discusses the erosive effect of blowing soot, steam, and fly ash as well as coal particle impingement and falling slag. It also includes several case studies.

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.

Corrosive environments can be broadly classified as atmospheric, underground/soil, water, acidic, alkaline, and combinations of these. Complicating matters is the fact that there are important variables, for example, pH, temperature, and the presence of biological organisms, that can significantly alter the response of the material in a given environment. This chapter provides a detailed account of all these types of corrosion affecting various industries, pointing out the connection between the characteristics of the corrosive environment that control corrosion behavior, the corrosion characteristics of various metals and materials systems, and the subsequent corrosion response.

This chapter compares and contrasts surface-engineering processes based on process availability, corrosion and wear performance, distortion effects, penetration depth or attainable coating thickness, and cost. It provides both quantitative and qualitative information as well as measured property values.

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.

High-strength steels are susceptible to stress-corrosion cracking (SCC) even in moist air. This chapter identifies such steels and the applications where they are typically found. It provides information on crack growth kinetics and crack propagation models in which hydrogen embrittlement is the predominant mechanism. It explains how different application variables affect SCC, including loading mode, state of stress, type of steel, temperature, electrochemical potential, heat treatment, and deformation processes. It also compares SCC characteristics in different high-strength steels and discusses the influence of composition, steelmaking practice, and application environment.

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 discusses the basic principles of corrosion, explaining how and why it occurs and how it is categorized and dealt with based on the appearance of corrosion damage or the mechanism of attack. It explains where different forms of corrosion are likely to occur and identifies metals likely to be affected. It also discusses the selection and use of protective coatings and the tests that have been developed to measure their effectiveness.

Amorphous alloys, because of their lack of crystallographic slip planes, are assumed to be insensitive to the selective corrosion attack that causes stress-corrosion cracking (SCC) in crystalline alloys. However, under certain conditions, melt-spun amorphous alloys have proven vulnerable to SCC due to hydrogen embrittlement. This chapter presents findings from several studies on this phenomenon, describing test conditions as well as cracking and fracture behaviors. It also discusses the effect of deformation on corrosion behavior, particularly for alloys without strongly passivating elements.

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.

The design process is the first and most important step in corrosion control. Major savings in operating costs are possible by anticipating corrosion problems so as to provide proper design for equipment before assembly or construction begins. This chapter describes the role of the design team in producing a successful final design, general considerations in corrosion-control design, and design details that accelerate corrosion. The details that must be considered when attempting to control corrosion by design include plant/site location, plant environment, component/assembly shape, fluid movement, surface preparation and coating procedures, and compatibility, insulation, and stress considerations. Design solutions for specific forms of corrosion, namely crevice corrosion, galvanic corrosion, erosion-corrosion, and stress-corrosion cracking, are then considered. A brief section is devoted to the discussion on corrosion allowance used for steel parts subject to uniform corrosion. Finally, the chapter describes the design considerations for using weathering steels.