Digital 3D reconstruction of microstructure and crack initiation in ductile iron casting for the qualification of methods for the safety assessment of nuclear waste containers

Project description

Ductile iron is characterized by a ferritic matrix with spherical graphite particles. Relevant microstructure parameters include the morphology (size distribution and shape) of the graphite particles, which essentially determine the mechanical behavior. The failure mechanisms in the material are extremely complex, determined by a multifaceted interaction of brittle and ductile failures which depend upon temperature, stress rate, and stress state. The complexity described above means that simplifications were necessary at various levels in the currently prescribed safety assessment relative to the established state of the art. The assessment levels are microstructure characterization, experimental determination of dynamic crack initiation parameters, and computational assessment via microstructure simulation.

Using digital analysis methods and tools such as computer tomography and 3D micrograph imaging, it appears possible to further develop, refine, and verify the three conventional methods of safety assessment for nuclear safety components discussed above. This will lead to a better understanding and a more accurate description of the complex microstructure-crack interaction under dynamic impact loading. The findings would make an important contribution to the preparation of final storage, particularly regarding the safety assessment of the transport of nuclear waste containers after extended interim storage periods.