RECOVERY MEASUREMENTS DURING TERTIARY CREEP OF ALPHA-IRON

Constant stress creep tests have been carried out on pure iron at temperatures of 542, 593, 650, 705°C to determine the shapes of the tertiary creep curves. The results show that the creep curves are of a similar form to those observed in f.c.c. metals. Recovery measurements throughout tertiary creep at 650°C show that the instantaneous rate of deformation is directly proportional to the recovery rate for the majority of the tertiary creep period. However, deviations from this relationship were found in the initial period of tertiary creep. No change occurred in the activation volume for the deformation process throughout the creep life. The results are interpreted on the basis that cavities must grow to a critical size before they can affect the rate of deformation. © 1969.