U.S.-Czech Engineering Research on Dislocation Substructure and Crack-Tip Blunting on the Brittle-to-Ductile Transition in Iron and Structural Steels

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INT 9707863 Beltz This U.S.-Czech engineering research project between Glenn Beltz of the University of California, Santa Barbara, and Anna Marchova of the Czech Institute of Thermomechanics, Prague, will address mechanical failure and atomic scale defect formation. These processes influence the ductile versus brittle nature of structural materials. Such characteristics have significance when considering the performance and reliability of high strength steels and advanced intermetallic alloys, especially when they are subject to adverse conditions such as low temperature or harsh chemical environments. The researchers intend to model this material behavior on macroscopic to atomistic scales. Specifically, efforts will feature examination of: 1) the phenomenon of "brittle" crack growth in pre-existing, apparently mobile, dislocations and 2) the role of nanoscale blunting of a sharp crack spreading through a dislocation-free zone, embedded in a plastically deforming medium. Results are expected to improve our understanding of brittle-to-ductile transition and to yield practical methods for reducing the likelihood of brittle failure of structural metallic alloys. This materials engineering research project fuldills the program objective of advancing scientific knowledge by enabling experts in the United States and Central Europe to combine complementary talents and share research resources in areas of strong mutual interest and competence. ??