Corrosion Engineering

Principles and Solved Problems

Branko N. Popov

• Publisher: Elsevier
• Year: 2015
• ISBN:
  9780444627278
• Topic: Physical Sciences
• Subtopic: Physical & Theoretical Chemistry

Corrosion Engineering: Principles and Solved Problems covers corrosion engineering through an extensive theoretical description of the principles of corrosion theory, passivity and corrosion prevention strategies and design of corrosion protection systems. The book is updated with results published in papers and reviews in the last twenty years. Solved corrosion case studies, corrosion analysis and solved corrosion problems in the book are presented to help the reader to understand the corrosion fundamental principles from thermodynamics and electrochemical kinetics, the mechanism that triggers the corrosion processes at the metal interface and how to control or inhibit the corrosion rates. The book covers the multidisciplinary nature of corrosion engineering through topics from electrochemistry, thermodynamics, mechanical, bioengineering and civil engineering.

• Addresses the corrosion theory, passivity, material selections and designs
• Covers extensively the corrosion engineering protection strategies
• Contains over 500 solved problems, diagrams, case studies and end of chapter problems
• Could be used as a text in advanced/graduate corrosion courses as well self-study reference for corrosion engineers

Chapter 1

Evaluation of Corrosion

Abstract

This chapter provides an introduction to subsequent chapters. It presents corrosion engineering goals to reduce impact. It evaluates corrosion cost and significance for preventing catastrophic failure in bridges, nuclear facilities, airplane components, and equipment in chemical, petrochemical, transportation, and construction industries. It briefly explains corrosion initiation conditions, electrochemical polarization, and passivity to show a relationship with different corrosion types including uniform corrosion attack, galvanic corrosion, pitting, crevice corrosion, stress corrosion cracking, intergranular corrosion, filiform corrosion, and hydrogen damage. The chapter also describes corrosion rate determination techniques and corrosion rate calculation from corrosion current.

Keywords

Introduction to corrosion engineering

Corrosion initiation

Electrochemical polarization

Passivity

Corrosion types

Corrosion current

Corrosion rate determination

Chapter Contents

1.1 Significance and Cost of Corrosion 2

1.2 Definition 2

1.3 Conditions for the Initiation of Corrosion 3

1.4 Electrochemical Polarization 4

1.5 Passivity 6

1.6 Types of Corrosion 8

1.7 Brief Description of Different Types of Corrosion 9

1.7.1 Uniform corrosion 9

1.7.2 Galvanic corrosion 9

1.7.3 Pitting corrosion 11

1.7.4 Crevice corrosion 14

1.7.5 Filiform corrosion 15

1.7.6 Stress corrosion cracking 16

1.7.7 Metallurgy of SCC 17

1.7.8 Solid solution composition and grain boundary segregation 18

1.7.9 Alloy phase transformation and associated solute depleted zones 18

1.7.10 Duplex structure 20

1.7.11 Cold work 20

1.7.12 Hydrogen embrittlement 21

1.7.13 Corrosion fatigue cracking 22

1.8 Corrosion Rate Determination 24

1.8.1 Calculation of corrosion rate form corrosion current 24

References 26

1.1 Significance and Cost of Corrosion

Corrosion compromises structure safety and is a leading factor in the catastrophic failure in bridges, nuclear facilities, airplane components, and equipment used in chemical, petrochemical, transportation, and construction industries. Corrosion is a spontaneous, slow-progressing phenomenon. The rate is mainly governed by the environment, metal composition, and metallurgical, chemical, and electrochemical properties. Because it takes a long time to evaluate the extent of corrosion, it is often underestimated in industrial equipment and structure design.

Corrosion is a major expense in estimating production cost and investments in any industry. According to a recent study, the direct cost of corrosion is estimated to be approximately $276 billion in the United States [1]. These losses are sustained by industry and government and constitute 3.2% of the gross domestic product (GDP). The direct cost of corrosion is considered the cost of replacing corroded structures and labor. Indirect losses add billions of dollars. The following losses are considered indirect costs: product loss, shutdown, efficiency loss, product contamination, metal and food and structure and equipment over design, for example, using more expensive, overqualified materials.

1.2 Definition

Corrosion is the spontaneous destruction of metals and alloys caused by chemical, biochemical, and electrochemical interaction between metals and alloys and the environment. Corrosive environments include moisture, oxygen, inorganic and organic acids, high pressure, temperature, and chlorides. During corrosion, metals tend to convert to more thermodynamically stable compounds such as oxides, hydroxides, salts, or carbonates. Recovering the original compounds (minerals and ores) from metals by spontaneous corrosion as the result of a decrease in free energy. Hence, the energy used for metal winning from ore or alloying is emitted during corrosion reactions [2,3].

Corrosion processes are classified as chemical, biochemical, and electrochemical corrosion. In order for corrosion to proceed as a chemical reaction, the reacting particles must come into contact to transfer the electrons. Thermodynamically, the reaction is governed by the ratio of internal energy to activation energy. The laws of heterogeneous chemical reactions control spontaneous metal destruction. Examples of chemical corrosion are destructive metal interaction with nonconductive organic compounds and high-temperature corrosion in the presence of a...