Crack Formation under Monotonic Creep and Creep Fatigue Interactions at Elevated Temperatures.

摘要

The development of interfacial stresses around non-deformable particles have been investigated under several different conditions: (a) either directly imbedded into a plastically deforming medium or a medium creeping according to a power law; (b) situated on a sliding boundary that transmits only normal tractions and separates media creeping according to a power law. In addition, stresses around triple grain boundary junctions have been computed across those boundaries normal to the tensile stress, adjoining two other boundaries transmitting only normal traction. The changes in the fatigue crack propagation rate in 304 Stainless Steel due to previously introduced intergranular creep cracks have been investigated at both room temperature and 700 C in both air and vacuum. The measured accelerations or decelerations of the fatigue crack are no larger than the specimen to specimen scatter observable in normal fatiuge research. (Author)