2. SUMMARY OF CREEP-FATIGUE CRACK GROWTH TESTS
Creep-fatigue crack growth tests of Grade 91 at 600oC under various load ratios and hold times were performed using compact tension (C(T)) specimens to investigate crack growth behavior under fully reversed creep-fatigue cyclic loading condition [28]. The C(T) specimen had the thickness of 20 mm, net thickness of 16 mm and width of 50mm. Chemical composition of the tested material is given in Table 1, together with those of other similar materials, ASME Grade 91 [40] and European X10CrMoVNb9-1 [41]. Material properties of these similar materials will be used for analysis in this paper.
Creep-fatigue crack growth test conditions for three tests are schematically shown in Fig. 1 and summarized in Table 2. The plastic limit load P0 was calculated using the following equation [42]