Creep-fatigue interaction is a principal cause of failures of many engineering components under high temperature and cyclic loading. In this work, stress controlled creep-fatigue interaction tests are carried out for modified 9Cr-1Mo (P91) steel. In order to study the damage mechanism of P91 steel under creep-fatigue interaction, Scanning Electron Microscopy (SEM) of specimen fracture morphology and in-situ observation experiments were conducted. Based on the ductility exhaustion theory and creep-fatigue interaction tests data, the modified ductility exhaustion life prediction model was developed. The predicted results are in a good agreement with the experiment. By comparison with frequency separation model, the life predicted by ductility exhaustion model is better than frequency separation model obviously. The results show that different stress amplitude and mean stress have great effect on the fracture damage mechanism when the hold time is invariable. By the SEM analysis of fracture morphology, the damage characters of creep, creep-fatigue interaction and fatigue can be partitioned. The specimen crack initiation source is the modified 9Cr-1Mo steel inclusion. Therefore, this work can provide a reference of life prediction and design for high temperature materials and components.
Study of Life Prediction and Damage Mechanism for Modified 9Cr-1Mo Steel Under Creep-Fatigue Interaction
Nanjing University of Technology,
Contributed by the Pressure Vessel and Piping Division of ASME for publication in the Journal of Pressure Vessel Technology. Manuscript received April 3, 2012; final manuscript received December 13, 2012; published online June 11, 2013. Assoc. Editor: Osamu Watanabe.
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Zhang, G., Zhao, Y., Xue, F., Wang, Z., Mei, J., Zhang, L., and Zhou, C. (June 11, 2013). "Study of Life Prediction and Damage Mechanism for Modified 9Cr-1Mo Steel Under Creep-Fatigue Interaction." ASME. J. Pressure Vessel Technol. August 2013; 135(4): 041402. https://doi.org/10.1115/1.4023424
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