1997 Volume 83 Issue 6 Pages 371-376
The delayed fracture characteristics of a PC bar steel have been examined under the FIP test. Earlier fracture occurs by applying cyclic stress compared with the constant stress even when the maximum stress is the same. The peak temperature of desorption of hydrogen at thermal desorption analysis is about 473K. Both the amount of diffusible hydrogen and desorption rate at room temperature of specimens just after the FIP test are irrelevant to the stress mode. After annealing the specimens at 473K for 30min after the test and reimmersing in the FIP solution, the total amount of diffusible hydrogen decreases to about 2/3. The effect of cyclic stressing appeares as the increase in the reduction of hydrogen released up to 473K. It is discussed that the effect of cyclic stressing on the delayed fracture characteristics is through a dynamical interaction of hydrogen with defects produced by plastic deformation.
