Cyclic crack growth in high-temperature water-results of an international testing round robin

The results are reported of a testing round robin performed under the auspices of the International Cyclic Crack Growth Group. Fourteen members of the Group participated in the round robin, in which measurements of cyclic crack growth rate were made on nominally identical compact tension specimens of SA533B pressure vessel steel immersed in high purity water at 561K. The plots of crack growth per cycle versus stress intensity factor range obtained by the participants were in acceptable agreement for specimens tested at a frequency of 1 Hz differed by up to an order of magnitude (in terms of crack growth rate) for tests at 0.017 Hz. Possible sources of interlaboratory scatter are discussed and it is suggested that the observed variations in the environmental contribution to crack growth arise because of inadvertent differences between the chemical environments to which the specimens were exposed during testing. Plans for a second testing program are reviewed