Application of J-Integral to High-Temperature Crack Propagation: Part I—Creep Crack Propagation

Crack propagation tests in creep were carried out on 0.16 percent carbon steel at 400 and 500°C in air and at 400°C in vacuum, on Type 316 stainless steel at 600 and 650°C in air, and on Type 304 stainless steel at 650°C in air and vacuum. As a nonlinear fracture mechanics approach, the applicability of the creep J-integral for a controlling parameter of the crack propagation rate was investigated using a few types of specimens subjected to constant tensile loads. A good correlation was obtained between crack propagation rate and creep J-integral. Crack propagation rate was nearly proportional to the creep J-integral, and the relationship was almost independent on the width of plate specimens, the test temperatures, the testing environments, and the fracture mode. The creep crack propagation rate in round notched bar specimens was a little smaller than that in the center notched plate specimens at the same magnitude of the creep J-integral.