Prediction of the Mechanical Response of a High Temperature Superalloy, Rene 95

摘要

The mechanical response of Rene 95 at 650 C. (1200 F) is predicted by the three different theories. First, the state variable model by Bodner and his coworkers is examined. A method is developed to calculate the state variable history from the Rene 95 data. This leads to a new presentation for the state variable and a direct method to determine some of the material parameters. Second, it is found that creep and stress relaxation can be correlated with isochronous curves; thus, the theory of Rabotnov and Papernik is examined. The model is extended to cyclic histories and a representation is developed specifically for Rene 95. Third, the model developed by Laflen and Stouffer for another super alloy is extended to Rene 95. It is also used to predict reverse plastic flow developed during cyclic histories. All models were found to reproduce the stress-strain and creep response very well. The models were also used to predict the cyclic behavior and stress relaxation. In general it is found that none of the models can adequately predict phenomena arising from damage such as tertiary creep. The study is concluded with a point-by-point comparison of the models. (Author)