Nucleation Threshold Stresses for the Dynamic Fracture of a Low-Alloy Ni-Cr Steel.

摘要

The stresses sigma(no) required for the nucleation of cracks with tensile stress waves were determined as a function of the strength of the steel. These threshold levels were established with the crack densities developed with parallel-plate impacts and the corresponding tensile stresses. The tensile stresses were determined with a procedure that accounts for the effects of elastic-plastic wave interactions and void development on the intensity of the tensile stresses. Two new results were discovered. First, it was established how sigma(no) depends on the yield strength of the material and, second, an equation was developed that describes how the crack nucleation rate changes with stress. This relation applies for the entire range of stresses extending from the stress at which cracking begins to at lest two and a half times this value.