Dynamic fracture toughness measurements of ferritic ductile cast iron

Hypothetical accident conditions for testing transport casks require the cask to withstand a 9-meter drop onto an unyielding target at a temperature of -29 C as described in the Office of Federal Register National Archives and Records Administrations Code of Federal Regulations, Title 10, Part 71, Packaging Transportation of Radioactive Material, 1983. The primary materials issue for ductile cast iron (DCI) under these loading conditions is its potential to fail via low-energy brittle fracture. DCI can, in fact, undergo a failure mode transition (with decreasing temperature and/or increasing loading rate) from a high-energy ductile tearing to a low-energy brittle fracture. Therefore, to be qualified for use in transport casks, the fracture toughness of candidate alloys should be measured at the elevated rates and low temperatures that match those required for licensing. Under such conditions it should be demonstrate that the material has sufficient toughness to preclude crack initiation