Investigator: RNDr. Luboš Kloc, CSc.
Number of Project: 1P05OC006
Agency: Ministry of Education, Youth and Sports, European cooperation COST 538
Duration: 01. 01. 2005 - 31. 12. 2008

A great majority of the creep data used for phenomenological lifetime prediction are obtained by the accelerated laboratory tests under conditions different from that used in industrial applications. The necessary extrapolation procedure without solid physical background makes lifetime predictions unreliable. High strain sensitivity creep tests recording the primary stage of the creep under conditions close to the service ones provide possibility of validation of the predictive capability of the constitutive models of the creep behaviour of high temperature materials. Since the creep cavities and other damage elements capable to grow up to critical sizes are nucleated during the primary stage, one can conclude that the models which failed in primary stage creep behaviour prediction fail in correct prediction of the creep lifetime, too.
Another important use of the high strain sensitivity creep testing techniques is the possibility to eliminate the errors caused by the different conditions in the creep tests of specimens taken from the plant components during and/or after service. However, the techniques does not allow the use of miniaturized creep specimens.

Kloc L., Sklenička V.:
Creep of 0.5CrMoV Steel at Very Low Strain Rates
in: J. Lecomte-Beckers et al. (eds.):
Materials for Advanced Power Engineering 2006
Forschongszentrum Julich 2006, vol. II, p. 1011