Most alloys are susceptible to intergranular corrosion, also known as intergranular attack (IGA), when exposed to specific environments. This article reviews the theory and application of acceptance tests for detecting the susceptibility of stainless steels and nickel-base alloys to IGA. It describes the most serious forms of structure-dependent corrosion, such as stress-corrosion cracking and exfoliation, in aluminum alloys including strain-Hardened 5xxx (Al-Mg) alloys and heat treated high-strength alloys. The article concludes with information on the evaluation tests for other alloys such as magnesium alloys and zinc die casting alloys.

This article briefly reviews the factors that influence the occurrence of intergranular (IG) fractures. Because the appearance of IG fractures is often very similar, the principal focus is placed on the various metallurgical or environmental factors that cause grain boundaries to become the preferred path of crack growth. The article describes in more detail some typical mechanisms that cause IG fracture. It discusses the causes and effects of IG brittle cracking, dimpled IG fracture, IG fatigue, hydrogen embrittlement, and IG stress-corrosion cracking. The article presents a case history on IG fracture of steam generator tubes, where a lowering of the operating temperature was proposed to reduce failures.

This article discusses the main materials and water chemistry characteristics of the primary and secondary water circuits of a pressurized water reactor (PWR). It reviews the corrosion issues of PWR materials and the influence of corrosion and fouling on primary and secondary circuit radiation fields. The article explains the primary side intergranular stress corrosion cracking (IGSCC) in different materials, namely, nickel-base alloys, high-strength nickel-base alloys, low-strength austenitic stainless steels, and high-strength stainless steels. The secondary side corrosion in steam generator including denting, pitting, intergranular attack and IGSCC is also discussed. The article examines laboratory studies that have resulted in models and computer codes for evaluating and predicting intergranular corrosion, and considers the remedial actions for preventing or arresting intergranular corrosion. It concludes with information on the external bolting corrosion in nuclear power reactors.

This article briefly reviews the various metallurgical or environmental factors that cause a weakening of the grain boundaries and, in turn, influence the occurrence of intergranular (IG) fractures. It discusses the mechanisms of IG fractures, including the dimpled IG fracture, the IG brittle fracture, and the IG fatigue fracture. The article describes some typical embrittlement mechanisms that cause the IG fracture of steels.

This article outlines the processes by which materials are selected to prevent or control localized corrosion, galvanic corrosion, and intergranular corrosion. It reviews the operating conditions and the design of candidate materials for material selection. The article discusses various corrosion-resistant materials, including ferrous and nonferrous metals and alloys, thermoplastics, reinforced thermosetting plastics, nonmetallic linings, glass, carbon and graphite, and catalyzed resin coatings. It examines an unusual form of intergranular corrosion known as exfoliation, which occurs in aluminum-copper alloys. The article also describes three types of erosion-corrosion: liquid erosion-corrosion, cavitation, and fretting. It concludes with information on the various factors to be considered for material selection, including minimum cost or economic design, minimum corrosion, minimum investment, and minimum maintenance.

Metallurgical variables, mainly carbon distribution and the presence of nitrogen and metallic phases, can influence the corrosion behavior of austenitic, ferritic, duplex, and martensitic stainless steels. This article describes the effects of these metallurgical and processing variables on the susceptibility of the stainless steels to intergranular corrosion and intergranular stress-corrosion cracking and their testing methods. It explains the effect of sigma and related phases on the corrosion behavior of stainless steels.

Steel automotive exhaust systems suffer from various forms of corrosion. This article illustrates exhaust system components with typical upper metal skin temperatures and alloys of construction. It discusses high-temperature corrosion of automotive exhaust systems, including oxidation, hot salt attack, and thermal fatigue. The article describes the various forms of corrosion which occur at the cold end of an exhaust system. The forms of cold end exhaust corrosion, including condensate pitting corrosion, exterior salt pitting, crevice corrosion, intergranular corrosion, and galvanic corrosion.

Advances in vehicle design and technology require engine coolant technology to minimize the degradation of nonmetals and prevent the corrosion of the metals in the cooling system. This article provides a detailed discussion on the functions, operation, materials, and major components of the cooling system. It discusses various forms of corrosion that occur in cooling systems, including uniform corrosion, galvanic corrosion, crevice corrosion, pitting corrosion, intergranular corrosion, erosion corrosion, and cavitation corrosion. The article presents information on engine coolant base components and inhibitors used for corrosion prevention. It reviews the coolant performance tests recommended by ASTM, SAE, and vehicle manufacturers. The article concludes with a description on the difference between light-duty automotive and heavy-duty diesel engine coolants.

This article describes the corrosion of principal parts of mining equipment such as mine shafts, wire rope, rock bolts, and pump and piping systems. It discusses the diagnosis and prevention of various types of corrosion including uniform corrosion, pitting corrosion, crevice corrosion, erosion-corrosion, and intergranular corrosion. The article explains the corrosion in tanks, reactor vessels, cyclic loading machinery, and pressure leaching equipment.

This article summarizes the Sendzimir process, the Cook-Norteman process, the coating types, composition, characteristics, and typical applications of various metallic coatings, such as zinc, aluminum, zinc-aluminum alloy, and aluminum-zinc alloy coatings. It provides a discussion on aqueous corrosion and atmospheric corrosion of galvanized steel and aluminized steel, as well as the intergranular corrosion of galvanized steel.

Cast stainless steels are usually specified on the basis of composition by using the alloy designation system established by the Alloy Casting Institute. This article discusses the corrosion behavior of heat-resistant alloys due to oxidation, sulfidation, and carburization. It describes the influence of the metallurgy of corrosion-resistant stainless steels on general corrosion, intergranular corrosion, localized corrosion, corrosion fatigue, and stress corrosion.

Zinc is one of the most used metals, ranking fourth in worldwide production and consumption behind iron, aluminum, and copper. This article commences with an overview of the applications of zinc that can be divided into six categories: coatings, casting alloys, alloying element in brass and other alloys, wrought zinc alloys, zinc oxide, and zinc chemicals. It discusses the corrosion and electrochemical behavior of zinc and its alloys in various environments, particularly in atmospheres in which they are most widely used. The article tabulates the corrosion rates of zinc and zinc coatings immersed in various types of waters, in different solutions in the neutral pH range, and in soils at different geographic locations in the United States. It concludes with information on the forms of corrosion encountered in zinc coatings, including galvanic corrosion, pitting corrosion, and intergranular corrosion.

This article focuses on the various forms of corrosion occurred in the passive range of aluminum and its alloys, namely, pitting corrosion, galvanic corrosion, deposition corrosion, intergranular corrosion, stress-corrosion cracking, exfoliation corrosion, corrosion fatigue, erosion-corrosion, atmospheric corrosion, filiform corrosion, and corrosion in water and soils. It discusses the effects of composition, microstructure, stress-intensity factor, and nonmetallic building materials on the corrosion behavior of aluminum and its alloys. The article also describes the corrosion resistance of anodized aluminum in contact with foods, pharmaceuticals, and chemicals.

This article provides a description of the classification, industrial applications, microstructures, physical, chemical, corrosion, and mechanical properties of zirconium and its alloys. It discusses the formation of oxide films and the effects of water, temperature, and pH on zirconium. The delayed hydride cracking of zirconium is also described. The article provides information on the resistance of zirconium to various types of corrosion, including pitting corrosion, crevice corrosion, intergranular corrosion, galvanic corrosion, microbiologically induced corrosion, erosion-corrosion, and fretting corrosion. The article explains the effects of tin content in zirconium and effects of fabrication on corrosion. Corrosion control measures for all types of corrosion are also highlighted. The article concludes with information on the safety precautions associated with handling of zirconium.

Exfoliation is a structure-dependent form of localized intergranular corrosion that follows grain boundaries in the rolling direction of wrought materials, particularly aluminum alloys. Highly cold-worked materials with elongated grain boundaries tend to be most affected. The article provides information on accelerated salt spray and total-immersion testing methods to help rate the exfoliation corrosion susceptibility of various aluminum alloys and alloy compositions. It also discusses visual assessment challenges and identifies several ASTM designations and where and how they apply.

This article addresses electrochemical methods for instantaneous rate determination and threshold determination as well as nonelectrochemical methods that can determine incremental or cumulative rates of corrosion. Electrochemical methods for the study of galvanic corrosion rates and localized corrosion and evaluation of corrosion rates under paints are also discussed. The article describes nonelectrochemical methods that can determine incremental or cumulative rates of corrosion. Methods presented include polarization methods, polarization resistance methods, electrochemical impedance methods, frequency modulation methods, electrochemical noise resistance, potential probe methods, cyclic potentiodynamic polarization methods, potentiostatic and galvanostatic methods, electrochemical noise (EN) methods, scratch-repassivation method, and electrochemical impedance spectroscopy (EIS) techniques. Gravimetric determination of mass loss, electrical-resistance methods, magnetic methods, quartz crystal microbalance method, solution analysis methods, and metrological methods are nonelectrochemical methods. The article presents an electrochemical test that examines the susceptibility of stainless steel alloys to intergranular corrosion.

This article addresses the forms of corrosion that contribute directly to the failure of metal parts or that render them susceptible to failure by some other mechanism. It describes the mechanisms of corrosive attack for specific forms of corrosion such as galvanic corrosion, uniform corrosion, pitting and crevice corrosion, intergranular corrosion, and velocity-affected corrosion. The article contains a table that lists combinations of alloys and environments subjected to selective leaching and the elements removed by leaching.

Corrosion is the electrochemical reaction of a material and its environment. This article addresses those forms of corrosion that contribute directly to the failure of metal parts or that render them susceptible to failure by some other mechanism. Various forms of corrosion covered are galvanic corrosion, uniform corrosion, pitting, crevice corrosion, intergranular corrosion, selective leaching, and velocity-affected corrosion. In particular, mechanisms of corrosive attack for specific forms of corrosion, as well as evaluation and factors contributing to these forms, are described. These reviews of corrosion forms and mechanisms are intended to assist the reader in developing an understanding of the underlying principles of corrosion; acquiring such an understanding is the first step in recognizing and analyzing corrosion-related failures and in formulating preventive measures.

Copper and copper alloys are widely used in many environments and applications because of their excellent corrosion resistance, which is coupled with combinations of other desirable properties. This article lists the identifying characteristics of the forms of corrosion that commonly attack copper metals as well as the most effective means of combating each. General corrosion, galvanic corrosion, pitting, impingement, fretting, intergranular corrosion, dealloying, corrosion fatigue, and stress-corrosion cracking (SCC) are some forms of corrosion. The article also lists a galvanic series of metals and alloys valid for dilute aqueous solutions, such as seawater and weak acids. It provides useful information on the effects of alloy compositions, selection for specific environments, and atmospheric corrosion of selected copper alloys. The article also tabulates the corrosion ratings of wrought copper alloys in various corrosive media.

This article discusses the corrosion resistance of aluminum and aluminum alloys in various environments, such as in natural atmospheres, fresh waters, seawater, and soils, and when exposed to chemicals and their solutions and foods. It describes the forms of corrosion of aluminum and aluminum alloys, including pitting corrosion, intergranular corrosion, exfoliation corrosion, galvanic corrosion, stray-current corrosion, deposition corrosion, crevice corrosion, filiform corrosion, stress-corrosion cracking, corrosion fatigue, and hydrogen embrittlement. The article also presents a short note on aluminum clad products and corrosion at joints.