A Code of Practice for conducting notched bar creep tests and for interpreting the data

This Code of Practice was first issued in 1991 by the High Temperature Mechanical Testing Committee, which now forms Committee TC11 of the European Structural Integrity Society (ESIS). It was issued as a result of the need to establish the multi-axial creep stress rupture properties of materials. The first issue was updated in 2001 as a result of user feedback, the findings of a collaborative European Commission BCR programme (Contract No. MATI-CT92-0033) to validate the procedure, and additional computer calculations performed by ALSTOM Power, British Energy, ERA and Imperial College. The main objectives of the first and second issues of this Code of Practice were to recommend a procedure for notched bar creep rupture testing at elevated temperatures and to provide the means of establishing the multi-axial creep rupture properties of engineering materials. In this new version, additional information is included to enable the multi-axial creep deformation response of a material to be extracted from the experimental data. Guidance is also given in this document for the conversion of deformation to strain. The Committee responsible for this revision is given in Appendix A. This Code of Practice is relevant to testpieces, which contain one or more circumferential notches with the generic shapes shown in Fig. 1. British, German and American Standards covering notched bar creep rupture testing consider only v-notches (see, e.g., Fig. 1d). Additional notch profiles have been included to allow a range of stress states in the notch throat to be examined. Guidance is given on how to interpret the data and select a notch profile to represent the stress state in the region of interest for the application in question. Advice is also provided on how to use the results of the tests to determine the influence of state of stress on the creep-deformation and rupture behaviour of the material being examined.