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.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of nickel alloys and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the fatigue crack, transgranular cleavage, intergranular fracture, grain boundaries, notch and fatigue precrack, dimpled rupture, and fatigue striations of these alloys.

This article is an atlas of fractographs that helps in understanding the causes and mechanisms of fracture of titanium alloys and in identifying and interpreting the morphology of fracture surfaces. The fractographs illustrate the fracture surface, fatigue crack growth, intergranular fracture, crack propagation, ductile overload fracture, dimpled rupture, microvoid coalescence, and quasi-cleavage fracture of these alloys.

The cracking process occurs slowly over the service life from various crack growth mechanisms such as fatigue, stress-corrosion cracking, creep, and hydrogen-induced cracking. Each of these mechanisms has certain characteristic features that are used in failure analysis to determine the cause of cracking or crack growth. This article discusses the macroscopic and microscopic basis of understanding and modeling fracture resistance of metals. It describes the four major types of failure modes in engineering alloys, namely, dimpled rupture, ductile striation formation, cleavage or quasicleavage, and intergranular failure. Certain fundamental characteristics of fracture observed in precipitation-hardening alloys, ferrous alloys, titanium alloys are also discussed.

As cast iron parts are extensively applied, fracture events will eventually take place. Consequently, it becomes essential to carry out failure analyses to identify the cause of fracture and to provide corrective actions that allow safe operation. This article presents a description of the main fracture modes and their characteristic fractographic features. It discusses the four principal fracture modes: dimple rupture (or fracture), cleavage, fatigue, and intergranular fracture. The article provides information on special cases of environmentally assisted fracture. It concludes with a description of fractographic analyses for identifying the direction of propagation of a crack.