Combined macrosopic and microscopic approach to the fracture of metals, period July 1974--June 1975. Technical progress report No. 38

During the report period major studies have been completed on (1) the microscale fracture conditions for the brittle and ductile fracture initiation modes at a macroscopic crack tip, (2) the formulation of dilational plasticity constitutive relations for void containing materials as applied to the inception of ductile rupture, (3) cavity growth during diffusive rupture processes as encountered in creep rupture at low stress but high temperature, and (4) particle and boundary strengthening mechanisms in carbon steels. In addition, work has continued on crack tip modeling by finite elements and mechanisms of ductile void growth near a crack tip. (auth)