Probability-creep strain-time curve and size effect of creep strain measurement

Abstract In this study, compressive creep tests were at first conducted on different types of specimens of Ti-6Al-4V titanium alloy by different loading methods. The results indicate that the loading method and specimen type generally have a significant impact on the test results of creep strain or creep curve at high creep stress levels. While such influence becomes less pronounced or negligible at low creep stress levels. Then, the dispersion of creep strain measurement is analyzed, and a probability-creep strain-time (P-C-T) curve is proposed to evaluate the survival probability of creep strain (i.e., probability of occurrence not exceeding a certain value of creep strain) or the creep strain at a certain survival probability. Finally, the size effect of creep strain measurement is investigated, and a model is proposed to correlate the difference in creep strain between specimens of different sizes. The predicted results are in good agreement with experimental data.