Statistical analysis on creep rupture life of 2.25Cr-1Mo steel on the basis of parameter regression models

Creep rupture lives of 2.25Cr-1Mo (T22) steel were statistically analyzed, through Manson-Haferd time-temperature parameter method, on the basis of Log-Normal, Weibull, Exponential, Gamma and Log-Logistic distribution parameter regression models, and subsequenty a comparison was made to the dependence of creep rupture time on the temperature and stress, the goodness-of-fit, and the median and 5th percentile of creep rupture time among selected models. Results show that all the distribution models except Exponential distribution are suitable for prediction of the creep rupture time, and the predited medians with the 1 models are very close, but their predictions on lower percentiles are different, expecially on scattered data, and the lower percentiles predicted with Weibull model are significantly lower than those with other models. Therefore, the creep rupture lifetime and long-term stress of 2.25Cr-1Mo steel should be comprehensively analyzed based on multiple distribution models.