Fracture toughness and fatigue crack growth (FCG) behaviours of structural materials for applications in prototype fast breeder reactor are being characterized in the authors' laboratory. Also, the effect of ageing on these properties has been evaluated after ageing over a range of temperatures and durations. The operating temperature ranges for these components often fall in the dynamic strain ageing (DSA) regime for these materials. In these studies, several manifestations of DSA, like decrease in fracture toughness, reduction in FCG resistance etc have been observed under various test and material conditions. These results are presented and discussed with reference to the need for considering these effects while generating the data for the design and integrity assessment of components. Also, concerns regarding experimental evaluation of these properties are highlighted.
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