In general, during LCF test for SSFS specimen, the strain deformation can be achieved by the applied displacement dividing the total effective gauge length. However, as can be seen from Fig.6b, it is very difficult to directly calculate the strain deformation since the length between the extensometers consisting of a parallel gauge length and transition fillet radius, thus, a useful deformation correlation between the parallel uniform gauge length (l0 ) and transition lengths could not be obtained. In the previous study, the researchers in the work57 utilized the reference stress approach to allow conventional creep data to be obtained from impression creep test data. Based on the same conception, the authors’ have proposed a new reference strain approach for scaling factor identification. On the basis of this, an empirical relationship between the parallel gauge (l0 ) and the total effective gauge length () is proposed based on the proposed scaling factor, β , as shown in Fig.6b. The total effective gauge length can be formulated, as follows: