Abstract
Strain rate is a key parameter in studying environmentally assisted cracking (EAC); it is, however, difficult to relate results obtained on specimens to in service components, owing to the problems involved in obtaining a correct estimate of strain rate when component geometry is complex and loading is variable with time. Nevertheless, it is possible to compare loading situations when a simpler parameter such as displacement rate is used; for example, results from fatigue, monotonic, and constant load testing can be correlated. Displacement rate is easier to measure on components in service and can be controlled, for instance by changing heating and cooling times; as a consequence, it is possible, on the basis of displacement rate, to predict remanent lifetimes. Moreover, by introducing a fracture mechanics approach to the study of EAC, it is possible to formulate, for individual situations, a fracture control plan to provide a quantitative description of EAC behaviour and to predict residual lifetimes for subcritically cracked components.
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