Sustained Load Crack Growth in Inconel 718 Under Non-Isothermal Conditions.

摘要

This investigation found linear cumulative damage modeling applicable to creep crack growth under non-isothermal conditions. The best results are obtained for high crack growth rates produced either by high temperature (above 593C), or by high stress intensities (K greater than 50 MPA square root of m). Except for one test, the linear model predicts conservative growth rates. Constant temperature data are collected for 537, 593, and 648C and presented as da/dt vs K curves. Center-cracked specimens of Inconel 718 are used. The isothermal baseline data are used to predict crack growth rates for the non-isothermal tests using linear cumulative modeling. The predicted creep crack growth rates were within a factor of two of the actual test data. The time-to-failure, predicted for one test, is 56 percent of the actual time to failure.