Creep Deformation Analysis of Grade 91 Steels and Prediction of Creep Strength Properties

Creep deformation behavior was analyzed on Grade T91 steels and an empirical equation was derived to express creep strain as a function of time. Creep rupture life prediction was investigated by means of the derived empirical equation. Influence of creep rupture strain on creep rupture life predicted by the derived equation was small over a range of creep rupture strain from 0.05 to 0.30, especially creep rupture strain of 0.10 and above. Prediction accuracy of creep rupture life of the equation was better than that of creep rupture data analysis with a Larson-Miller parameter. Heat-to-heat variation of long-term creep rupture strength was appropriately observed. Minimum creep rate, onset of tertiary creep, and time to specific strain are easily predicted by the equation.