Creep-fatigue properties of nickel-base superalloy 263

In this paper the creep-fatigue (CF) and low cycle fatigue (LCF) properties of alloy 263 are considered. Both virgin and pre-crept (750ºC / 178 MPa / 3000 h) test materials were tested to investigate the impact of creep damage prior to cycling. The tests performed on the high precision pneumatic loading system (HIPS) are in the temperature range of 700-750ºC, total strain range of 0.6-1.0% and with hold times in both tension and compression. Curves of peak stress as a function of cycles and curves of stress relaxation are presented for the alloy 263. The creep-fatigue test results are also analysed using methods described in the assessment and design codes of RCC-MR, R5 and ASME NH as well as by the recently developed -model. It is shown that the number of cycles to failure for CF data can be accurately predicted by the simple -model. The practicality in using the life fraction rule for presenting the combined damage is discussed and recommendations are given on alternative approaches