This article provides an overview of the classification of hydrogen damage. Some specific types of the damage are hydrogen embrittlement, hydrogen-induced blistering, cracking from precipitation of internal hydrogen, hydrogen attack, and cracking from hydride formation. The article focuses on the types of hydrogen embrittlement that occur in all the major commercial metal and alloy systems, including stainless steels, nickel-base alloys, aluminum and aluminum alloys, titanium and titanium alloys, copper and copper alloys, and transition and refractory metals. The specific types of hydrogen embrittlement discussed include internal reversible hydrogen embrittlement, hydrogen environment embrittlement, and hydrogen reaction embrittlement. The article describes preservice and early-service fractures of commodity-grade steel components suspected of hydrogen embrittlement. Some prevention strategies for design and manufacturing problem-induced hydrogen embrittlement are also reviewed.

This article begins with a discussion on the classification of hydrogen embrittlement and likely sources of hydrogen and stress. The article describes several hydrogen embrittlement test methods, including cantilever beam tests, wedge-opening load tests, contoured double-cantilever beam tests, rising step-load tests, and slow strain rate tensile tests. It also describes the interpretation of test results and how to control hydrogen embrittlement during production.

Hydrogen damage is a form of environmentally assisted failure that results from the combined action of hydrogen and residual or applied tensile stress. This article classifies the various forms of hydrogen damage and summarizes the theories that seek to explain these types of degradation. It reviews hydrogen degradation in specific ferrous and nonferrous alloys, namely, iron-base alloys, nickel alloys, aluminum alloys, copper alloys, titanium alloys, zirconium alloys, and vanadium, niobium, tantalum, and their alloys. An outline of hydrogen damage in intermetallic compounds is also provided.

This article describes the types, mechanism, and typical test methods along with their configurations for the evaluation of hydrogen embrittlement, stress-corrosion cracking, and corrosion fatigue with an emphasis on fracture mechanics methodologies for metals. An overview on the environmentally assisted crack growth of polymers is also included. The article details the evaluation of nanoscale environmental effects and indentation-induced cohesive cracking. It also provides information on scanning probe microscopy.

Hydrogen damage is a term used to designate a number of processes in metals by which the load-carrying capacity of the metal is reduced due to the presence of hydrogen. This article introduces the general forms of hydrogen damage and provides an overview of the different types of hydrogen damage in all the major commercial alloy systems. It covers the broader topic of hydrogen damage, which can be quite complex and technical in nature. The article focuses on failure analysis where hydrogen embrittlement of a steel component is suspected. It provides practical advice for the failure analysis practitioner or for someone who is contemplating procurement of a cost-effective failure analysis of commodity-grade components suspected of hydrogen embrittlement. Some prevention strategies for design and manufacturing problem-induced hydrogen embrittlement are also provided.

This article discusses the fundamental aspects of environmentally induced cracking. It provides a theoretical basis for the evaluation, testing, and methods of protection against the cracking. The article describes the mechanisms of corrosion that produce cracking of metals and intermetallic compounds as a result of exposure to their environment.

Stress-corrosion cracking (SCC) is a cracking phenomenon that occurs in susceptible alloys, and is caused by the conjoint action of tensile stress and the presence of a specific corrosive environment. This article provides an overview of the anodic dissolution mechanisms and cathodic mechanisms for SCC. It discusses the materials, environmental, and mechanical factors that control hydrogen embrittlement and SCC behavior of different engineering materials with emphasis on carbon and low-alloy steels, high-strength steels, stainless steels, nickel-base alloys, aluminum alloys, and titanium alloys.

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.

Analysis of the failure of a metal structure or part usually requires identification of the type of failure. Failure can occur by one or more of several mechanisms, including surface damage (such as corrosion or wear), elastic or plastic distortion, and fracture. This leads to a wide range of failures, including fatigue failure, distortion failure, wear failure, corrosion failure, stress-corrosion cracking, liquid-metal embrittlement, hydrogen-damage failure, corrosion-fatigue failure, and elevated-temperature failure. This article describes the classification of fractures on a macroscopic scale as ductile fractures, brittle fractures, fatigue fractures, and fractures resulting from the combined effects of stress and environment.

Tantalum is one of the most versatile corrosion-resistant metals known. The outstanding corrosion resistance and inertness of tantalum are attributed to a very thin, impervious, protective oxide film that forms on exposure of the metal to slightly anodic or oxidizing conditions. This article provides a discussion on the mechanism of corrosion resistance and on the behavior of tantalum in different corrosive environments, namely, acids; salts; organic compounds; reagents, foods, and pharmaceuticals; body fluids and tissues; and gases. It contains several tables that summarize the effects of acids, salts, and miscellaneous corrosive reagents on tantalum and applications for tantalum equipment in chemical, pharmaceutical, and other industries. Finally, the article presents a discussion on hydrogen embrittlement, the galvanic effects, and cathodic protection of tantalum and describes the corrosion resistance of different types of tantalum-base alloys.

This article describes the general factors that can influence fracture appearances. The focus is on the general practical relationships of fracture appearances, with factors presented in some broad categories, including: material conditions (e.g., crystal structure and microstructure); loading conditions (stress state, strain rate, and fatigue); manufacturing conditions (casting, metal-working, machining, heat treatment, etc.); and service and environmental factors (hydrogen embrittlement, stress corrosion, temperature, and corrosion fatigue).

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.

In this article, a basic summary of fracture mechanisms in carbon and alloy steels is presented, along with numerous examples of these fractures. These examples include ductile fracture, brittle cleavage fracture, intergranular fracture, fatigue fracture, and environmentally assisted failure mechanisms.

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.

Stress-corrosion cracking (SCC) occurs under service conditions, which can result, often without any prior warning, in catastrophic failure. Hydrogen embrittlement is distinguished from stress-corrosion cracking generally by the interactions of the specimens with applied currents. To determine the susceptibility of alloys to SCC and hydrogen embrittlement, several types of testing are available. This article describes the constant extension testing, constant load testing, constant strain-rate testing for smooth specimens and precracked or notched specimens of SCC. It provides information on the cantilever beam test, wedge-opening load test, contoured double-cantilever beam test, three-point and four-point bend tests, rising step-load test, disk-pressure test, slow strain-rate tensile test, and potentiostatic slow strain-rate tensile test for hydrogen embrittlement.

Embrittlement that occurs below the melting point of the embrittling species is known as solid metal induced embrittlement (SMIE) of metals. This article provides a discussion on the characteristics and investigations of SMIE, liquid metal induced embrittlement, and delayed failure. It also describes the mechanism of SMIE.

This article examines the embrittlement of iron and carbon steels. It describes compositional, processing, and service conditions that contribute to the problem and presents examples of how embrittlement influences mechanical properties. Embrittlement due to hydrogen is the most common form of embrittlement and influences the behavior and properties of nearly all ferrous alloys and many metals. The article explains why hydrogen embrittlement is so widespread and reviews the many types of damage it can cause. It also explores other forms of embrittlement, including metal-induced embrittlement, strain-age and aluminum nitride embrittlement, thermal embrittlement, quench cracking, 475 deg C and sigma phase embrittlement (in FeCr alloys), temper embrittlement, and embrittlement caused by neutron irradiation. In addition, the article covers stress-corrosion cracking along with properties and conditions that affect it, and the procedures to detect and evaluate it.

This article begins with a discussion of the basic fracture modes, including dimple ruptures, cleavages, fatigue fractures, and decohesive ruptures, and of the important mechanisms involved in the fracture process. It then describes the principal effects of the external environment that significantly affect the fracture propagation rate and fracture appearance. The external environment includes hydrogen, corrosive media, low-melting metals, state of stress, strain rate, and temperature. The mechanism of stress-corrosion cracking in metals such as steels, aluminum, brass, and titanium alloys, when exposed to a corrosive environment under stress, is also reviewed. The final section of the article describes and shows fractographs that illustrate the influence of metallurgical discontinuities such as laps, seams, cold shuts, porosity, inclusions, segregation, and unfavorable grain flow in forgings and how these discontinuities affect fracture initiation, propagation, and the features of fracture surfaces.

Stainless steel alloys have many unique failure mechanisms, including environmentally assisted cracking, cracking associated with welding, and secondary phase embrittlement. This article describes these failure mechanisms and the fracture modes associated with the different categories of stainless steel. These mechanisms and modes are grouped together because of their similarities across the categories.

This article discusses corrosion resistance of titanium and titanium alloys to different types of corrosion, including galvanic corrosion, crevice corrosion, stress-corrosion cracking (SCC), erosion-corrosion, cavitation, hot salt corrosion, accelerated crack propagation, and solid and liquid metal embrittlement. A short section discusses the addition of alloys that can improve the corrosion resistance of titanium.