Update and Improve Subsection NH ?? Alternative Simplified Creep-Fatigue Design Methods

Creep-fatigue life prediction through multiple regression analyses

“…The power-law relationship between creep-fatigue life and hold period is often observed for lots of materials. However, experimental results by Asayama [6] indicated that there was no strict linear relationship between t h and N f in double logarithmic coordinate for Mod.9Cr-1Mo steel when the hold period is very long. The creep-fatigue life decreased gradually with increasing the hold period.…”

“…The experimental data of 304 stainless steel and grade 91 steel are respectively collected from Refs. [4,8,10,[12][13][14] and [5][6][7] to obtain the constants in Eq. (7) through regression analyses and logarithmic transformation.…”

“…[4] and Refs. [5][6][7]. It can be seen that the value for N f linearly increases with increasing the value for 1-T T m ⁄ in double logarithmic coordinate.…”

“…[4,[9][10][11] and those of grade 91 steel from Refs. [5][6][7] are fitted by using Eq. (4), as seen in Fig.…”

A Recent Development in Creep-Fatigue Testing

“…In only one case had a thorough post-test microscopic characterization of the surface cracks been performed [41], with this evaluation involving a 2 % load drop crack initiation criterion. Although results for a creep-fatigue-based (with hold time) ILS existed for a temperature of 550 C [42], that study involved very limited global participation, and hence a new ILS was initiated to rigorously determine precision and bias statements for ASTM E2714-09 [15].…”