13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- it is shown that as the temperature increases, the fatigue life decreases. One also see that the linear lines can fit the data points quite well, in addition the two fatigue lines at two different temperature are almost parallel to each other in the log-log scale graphs. Therefore, the isothermal fatigue data can be fit by the following equation: ( )( ) 2 c f AT N ε∆ = (5) where ∆ε/2 is the strain amplitude (mechanical strain), Nf is the number of cycle to failure, c is a constant and A is a temperature dependent constant, where max min max max max min ( )( ) ( ) ( ) T T T T T A A AT A T T − − = − − (6) Tmax = 480°C and Tmin =100°C in this case. Figure 8 Isothermal fatigue Lives of SA387 GR.2 CL2 at 100 and 480oC Figure 9 Isothermal and TM fatigue lives of 410S Isothermal and thermal-mechanical fatigue lives of 410S are shown in Fig 9. From the results, it is shown the same trend as that of the isothermal fatigue tests for the material SA387 Gr. 22 CL2. Therefore the same form of the above equations (5) and (6) can be used to fit the fatigue life data
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