PSI - Issue 17

Feiyang He et al. / Procedia Structural Integrity 17 (2019) 72–79 Feiyang He/ Structural Integrity P o edi 00 (2019) 000 – 00

3

74

Figure 1 Evolution of crack growth rate with frequency at (a) different temperatures and ∆ (b) different temperatures (Merhy et al., 2013) Noguchi et al. (2018) investigated the TMF behaviours of the nickel-based 23Cr-45Ni-7W alloy as a material of high-efficiency thermal power boiler. The TMF properties obtained via the experiments are compared with isothermal fatigue (ITF) tests and bithermal fatigue (BTF) tests. The main conclusion was that the TMF life applied with OP loads was longer than IP loads which were similar to Pr etty et al. (2017)’s conclusion. Some other research paid more attention to the microstructure of the metal material and its effect on fatigue crack growth such as Ghonem (2010) and Dahal et al. (2013). Based on the microstructure, Suzuki et al. (2018) presented how primary and secondary orientations can affect the temperature dependent fatigue crack propagation in a single crystal Ni-base superalloy. Apart from experimental research, some publications proposed crack growth model for TMF. Kang et al. (2007) proposed a fatigue life prediction method to estimate TMF damage for variable temperature and loading amplitudes conditions. The model calculated the fatigue damage which was assumed as the sum of mechanical damage and oxidation damage. Rémy et al. (2007) developed a damage model using the propagation of micro-cracks originating at casting defects for nickel-based single crystal superalloys considering the oxidation-creep – fatigue interactions. The