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.

This article describes the incubation, nucleation, and propagation of stress-corrosion cracking and how to evaluate it using standard tests. It discusses constant-strain, constant-load, bending, and uniaxial tension testing and how they compare when evaluating smooth and precracked test specimens under elastic-strain, plastic-strain, and residual-stress conditions. The article provides guidance on specimen selection and preparation, strain rate, and test equipment. It also examines service and laboratory test environments and provides detailed information on how to test various steels and alloys and how to interpret test results.

Measurement and analysis of fracture behavior under high loading rates is carried out by different test methods. This article provides a discussion on the history and types of notch-toughness tests and focuses exclusively on notch-toughness tests with emphasis on the Charpy impact test. It reviews the requirements of test specimens, test machine, testing procedure and machine verification, application, and determination of fracture appearance and lateral expansion according to ASTM A370, E 23, and A 593 specifications. In addition, the article includes information on the instrumentation, standards and requirements, and limitations of instrumented Charpy impact test, which is carried out in specimens with induced fatigue precrack. The article concludes with a review of the requirements of drop weight testing and the specimens used in other notch-toughness tests.

Catastrophic failure best typifies the characteristic behavior of brittle solids in the presence of cracks or crack-like flaws under ambient conditions. This article provides a description of the concepts of fracture mechanics of brittle solids and focuses on the various testing methods developed to characterize the fracture behavior of brittle solids with examples. These include the fracture toughness test method and R-curve test method at ambient and elevated temperatures. The article also includes information on the evaluation of fracture-toughness test results and the behavior of R-curve.

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 describes the test methods of fracture toughness, namely, linear-elastic and nonlinear fracture toughness testing methods. Linear-elastic fracture toughness testing includes slow and rapid loading, crack initiation, and crack arrest method. Nonlinear testing comprises J IC testing, J-R curve evaluation, and crack tip opening displacement (CTOD) method. Other methods used include the combined J standard method, the common fracture toughness test, transition fracture toughness testing, and the weldment fracture testing method.