Abstract
The creep crack growth behavior in a bar with a circumferential hyperbolic crack was analysed by means of a method proposed in previous papers. This method combines the stress and strain analysis with a generalized creep damage hypothesis applied to the point located ahead of the current crack by a characteristic length ρs. The effect of several parameters on the creep crack growth behavior was discussed. In parallel with this analysis creep rupture tests of deeply precracked round bars, which simulate the bars with a hyperbolic crack, were carried out on S15CK low carbon steel at 450°C.
The results obtained are summarized as follows:
(1) The analytical predictions as to the creep rupture lives of deeply cracked bars agreed well with the experimental data.
(2) It was reconfirmed by the experimental data that notch-weakening prevails under torsional creep in the absence of metallurgical strengthening mechanisms.
(3) It was found that rupture life of a precracked specimen can be successfully correlated with the initial value of modified J-integral, which is a measure of stress and strain fields in the vicinity of a precrack under the steady-state creep conditions.
