| Abstract: With the development of electric power industry in our country, life management of thermal equipments in fossil fuel thermal has become more and more important. The knowledge on the properties of used materials is urgently needed for reasonable life-prediction and life-distribution. As cylinder bolts are concerned, they often rapture at the first tooth-root resulting from lower high temperature strength of their material and higher stress. Since bolts operate at high temperature environment, creep skew and damage causing their failure are important factors that can not been neglected. Therefore, this thesis studied the creep properties of 2Cr11NiMoVNbNB steel which is one of bolt material used in 300MW stream turbine. The main work is as follows:1. Creep experiments of 2Cr11NiMoVNbNB were carried out at temperature of 550℃and 600℃ and stress from 200MPa to 500MPa. In addition, creep experiments were also carried out at the stress of 330MPa and 350MPa at temperature from 540℃ to 700℃.2. The creep data were processed and analyzed with mathematical method. Based on the experimental results, curve of creep rate versus stress and of creep rate versus temperature were curved.3. Nonlinear Least Square method programs which are used to curve fitting were programmed in Matlab language. Creep data of 600℃ were curved and analysized based on strain hardness theory and function method.4. Creep life -prediction model was put forward from creep experimental results.5. Creep damage model was put forward from creep experimental results.
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