Measurement of creep strain. (a) The influence of order-disorder transformations in Ni-Cr-base alloys; (b) a Code of Practice for the use of Ni-base alloy extensometers

Revision is currently underway of both the Creep Testing and the Extensometer Calibration Standards by the ISO committee TC164 SC1 which prompted the need to update the Code of Practice giving guidance on the use of Ni-base alloy extensometry to avoid the erroneous measurement of negative creep. This paper presents the underlining evidence of the dimensional changes due to order–disorder transitions in Ni-base super-alloys used for extensometer limbs and provides an updated version of the Code of Practice.