PSI - Issue 19

Yasuhiro Yamazaki et al. / Procedia Structural Integrity 19 (2019) 538–547 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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4. Conclusions

In this study, the growth behavior of physically short fatigue crack and its temperature dependence in a single crystal Ni-base superalloy under out-of-phase type thermomechanical fatigue (TMF) were investigated. The experimental results indicate that the short fatigue crack growth resistance decreases with temperature. There is no change in macroscopic morphology of crack growth path in either test conditions. In order to investigate the crack opening behavior, the FE analysis was also conducted taking into consideration the temperature dependence on the deformation behavior. However, even when the temperature dependences in crack closure and elastic modulus are taken into account, the temperature dependence of crack propagation resistance still remains. The oxidation became significantly around the crack tip under the higher temperature condition and the growth behavior of the oxide layer depends on the temperature, time and mechanical strain. It was found from the experimental and numerical investigation that the environmental effects at crack tip pay the critical role on the small fatigue crack propagation. The newly prediction method taking into account the oxidation effect on crack propagation was proposed. The proposed method provides good prediction results for the short fatigue crack propagation under out-of-phase type thermomechanical fatigue. Kuwabara, M., Harada, S, 2015, Progress of higher temperature and efficiency of large scale gas turbine and future prospects, Journal of the gas turbine society of Japan 43, 308 - 314 (in Japanese). Bernstein, H.L., Grant, T.S., McClung, R.C., Allen, J.M., 1993, Prediction of thermal - mechanical fatigue life for gas turbine blades in electric power generation, ASTM STP 1186, 212 - 238. Ito, A., Kobayashi, D., 2015, Degradation evaluation of 1300°C - class 1st - stage gas turbine blades after long - term service, International Gas Turbine Congress 2015, Tokyo, Japan, 614 - 619. Zhou, H., Harada, H., Ro, Y., Kobayashi, Y., Koizumi, Y., 2003, Aspects of thermomechanical fatigue of two single crystal nickel based superalloys, Materials Science and Technology. 19, 847 - 852. Okazaki, M., Take, K., Kakehi, K., Ssaken, M., Yamazaki, Y., Kaneko, H., Fujiyama, K., Namba, K., Yokomaku, T. Nonaka, I., Arai, M., Sugita, Y., Sakurai, S., Harada, Y., 2003. Collaborative Research on Thermo - Mechanical and Isothermal Low - Cycle Fatigue Strength of Ni - Base Superalloys and Protective Coatings at Elevated Temperatures in The Society of Materials Science, Japan (JSMS), ASTM STP 1428, 180 194. Miller, M.P., McDowell, DL., Oehmke, R.L.T., Antolovich, S.D., 1993, A life prediction model for thermomechanical fatigue based on microcrack propagation, ASTM STP 1186, 35 - 39. Okazaki, M., Yamada, H., Nohmi, S., 1996, Temperature dependence of the intrinsic small fatigue crack growth behavior in ni - base superalloys based on measurement of crack closure, Metallugical and Materials Transactions A 27, 1021 - 1031. Sengupta, A., Putatunda, S. K., Bartosiewicz, L., Hangas, J., Nailos, P. J., Peputapeck, M., Alberts, F. E., 1994, Tensile behavior of a new single crystal nickel - based superalloy (CMSX - 4) at room and elevated temperatures, J. of Materials Engineering and Performance 3, 73 - 81. Koizumi, Y., Yokokawa, T., Harada, H., Kobayashi, T., 2006, Database of Creep Property for Nickel - Base Single Crystal Superalloys, RenéN4, RenéN5 and CMSX - 4, J. of the Japan Institute of Metals and Materials 70, 176 - 179 (in Japanese). Mukai. Y., Kagawa. H., Sakaguchi. M., M. Okazaki, 204, Evaluation of thermo - mechanical fatigue crack propagation behavior of Ni - based single crystal superalloy CMSX - 4, Transactions of the JSME 80, SMM0294 (in Japanese). Rice, J. R., 1968, A Path Independent Integral and the Approximate Analysis of Strain Concentration by Notches and Cracks, J. of Applied Mechanics 35, 379 - 386. Shih, C. F., 1981, Relationship between the J - Integral and the Crack Opening Displacement for Stationary and Extending Cracks, J. of the Mechanics and Physics of Solids 29, 305 - 326. Newman, Jr., J. C., Raju, I. S., 1984, Stress - intensity factor equations for cracks in three - dimensional finite bodies subjected to tension and bending loads, NASA Technical Memorandum, 85793. Remy, L., Bernard, H., Malpertu, J. L., Rezai - Aria, F., 1993, Fatigue Life Prediction Under Thermal - Mechanical Loading in a Nickel - Base Superalloy, ASTM STP 1186, 3 - 16. Reuchet, J., Remy, L. , 1983, Fatigue Oxidation Interaction in a Superalloy – Application to Life Prediction in High Temperature Low Cycle Fatigue, Metallurgical Transactions A 14A, 141 - 149. Acknowledgements Authors would be express sincere thanks for the financial support from the JFE 21st Century Foundation. References