13th International Conference on Fracture June 16–21, 2013, Beijing, China -6- Two approaches, analytical analysis and finite element analysis are implemented to establish the strain correlation at elevated temperature for each material. The results are then compared with the experiments to verify the established correlations at each temperature. Figure 7 Comparison of room temperature correlation coefficients The correlation coefficients between the experiment and the two analysis methods are shown in Fig. 7. It can be seen that the experimental points are mainly fallen in the range between the two correlation curves by the analytical and FEA methods. At higher strain range, those points are closer to the FEM correlation curve. However, the difference of the correlation coefficients predicted by the analytical and FE methods is about only 4% when the strain is up to 0.8%. Therefore, a mean curve of the two predictive curves is suggested to be used. In addition, the strain correlation technique can also be applied to thermal-mechanical fatigue tests. 2.4. Materials and Test program Table 1 Tested coke drum materials Name Nominal Chemical Comp. Plate SA387 Gr. 22 CL2 2 ¼Cr-1 Mo Base SA 240 TP410S 13Cr Clad In this paper, low cycle fatigue tests conducted for the following materials: SA387 Gr. 22 CL2 and 410S. Uni-axial isothermal low cycle fatigue tests were carried out as benchmark tests. The tests are under strain-controlled condition at rate of 0.005/Sec. The tests were conducted at fully-reversed cyclic loading condition (R=εmin/εmax = -1) at both 100 and 480°C. In addition, TMF tests were conducted on 410S. The tests are under temperature-dependent strain-controlled condition, and in-phase thermal-mechanical loading was applied. 3. Results Isothermal fatigue lives of SA387 Gr.22 CL 2 at 100 and 480oC are shown in Fig 8. From the results,
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