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 aims to identify and illustrate the types of overload failures, which are categorized as failures due to insufficient material strength and underdesign, failures due to stress concentration and material defects, and failures due to material alteration. It describes the general aspects of fracture modes and mechanisms. The article briefly reviews some mechanistic aspects of ductile and brittle crack propagation, including discussion on mixed-mode cracking. Factors associated with overload failures are discussed, and, where appropriate, preventive steps for reducing the likelihood of overload fractures are included. The article focuses primarily on the contribution of embrittlement to overload failure. The embrittling phenomena are described and differentiated by their causes, effects, and remedial methods, so that failure characteristics can be directly compared during practical failure investigation. The article describes the effects of mechanical loading on a part in service and provides information on laboratory fracture examination.

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.

Overload failures refer to the ductile or brittle fracture of a material when stresses exceed the load-bearing capacity of a material. This article reviews some mechanistic aspects of ductile and brittle crack propagation, including a discussion on mixed-mode cracking, which may also occur when an overload failure is caused by a combination of ductile and brittle cracking mechanisms. It describes the general aspects of fracture modes and mechanisms. The article discusses some of the material, mechanical, and environmental factors that may be involved in determining the root cause of an overload failure. It also presents examples of thermally and environmentally induced embrittlement effects that can alter the overload fracture behavior of metals.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of one specific type of cemented carbide, tungsten carbide. It also assists in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the brittle fracture, transgranular fracture, intergranular fracture, and crack propagation of the tungsten carbide.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of precipitation-hardening stainless steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the cup-and-cone tension-overload fracture, low-cycle and high-cycle fatigue fracture, fracture surface, brittle intergranular fracture, hydrogen embrittlement, and intergranular stress-corrosion cracking of stainless steel components of these steels. The components include high-pressure compressor parts, springs, deflector yokes of aircraft main landing gears, and aircraft engine mount beams.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of austenitic stainless steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the following: fatigue-crack fracture, rock candy fracture, cleavage fracture, brittle fracture, high-cycle fatigue fracture, fatigue striations, hydrogen-embrittlement failure, creep crack propagation, fatigue crack nucleation, intergranular creep fracture, torsional overload fracture, stress-corrosion cracking, and grain-boundary damage of these steels. The austenitic stainless steel components include spring wires, preheater-reactor slurry transfer lines and gas lines of coal-liquefaction pilot plants, oil feed tubes and suction couch rolls of paper machines, cortical screws and compression hip screws of orthopedic implants, and Jewett nails.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of ASTM/ASME alloy steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the solidification cracking, creep failure, brittle fracture, fracture by overpressurization, inclusion effect, fatigue crack propagation, ductile fatigue striation, secondary cracking, intergranular fracture, and elevated-temperature fracture of alloy steels used in pressure vessels, steam boiler superheater tubes, and box-girder bridges.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of low-carbon steels and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the following: the intergranular fracture, bending impact fracture, brittle fracture, tensile-test fracture, transgranular fracture, cleavage fracture, delayed fracture, corrosion fatigue, inclusion morphology, fatigue crack propagation, and in-service fatigue fracture of various automotive components. These components include tie rod adjusting sleeves, automotive bolts, hydraulic jack shafts, crank handle collars, boiler tubes, drive shafts, bicycle pedal axles, lift-truck hydraulic-piston rods, and steel springs.

This article discusses the visual and microscopic characteristics of fractures of cast alloys. These fractures include ductile rupture, transgranular brittle fracture, intergranular fracture, fatigue, and environmentally induced fracture. The article also describes the factors that affect fracture appearance.

Stress-corrosion cracking (SCC) is a phenomenon in which time-dependent crack growth occurs when the necessary electrochemical, mechanical, and metallurgical conditions exist. This article provides an overview of the environmental phenomenon, mechanisms, and controlling parameters of SCC. It describes the phenomenological and mechanistic aspects of the initiation and propagation of SCC. The article includes a phenomenological description of crack initiation and propagation that describes well-established experimental evidence and observations of stress corrosion. Discussions on mechanisms describe the physical process involved in crack initiation and propagation. The article also includes information on dissolution models and mechanical fracture models.

This article provides an overview of fractography and explains how it is used in failure analysis. It reviews the basic types of fracture processes, namely, ductile, brittle, fatigue, and creep, principally in terms of fracture appearances, such as microstructure. The article also describes the general features of fatigue fractures in terms of crack initiation and fatigue crack propagation.

Visual examination, using the unaided eye or a low-power optical magnifier, is typically one of the first steps in a failure investigation. This article presents the guidelines for selecting samples for scanning electron microscope examination and optical metallography and for cleaning fracture surfaces. It discusses damage characterization of metals, covering various factors that influence the damage, namely stress, aggressive environment, temperature, and discontinuities.