2017 年 66 巻 6 号 p. 413-419
Creep strain equations of Grade 92 steel which is used in boilers and piping systems of ultra-supercritical (USC) thermal power plants were developed based on the results of creep tests using smooth round bar specimens of three different sources of Grade 92 steels. In these equations, primary creep behavior was represented by a power-law function of time and tertiary creep behavior was described by an exponential function of time. Parameters in these equations were determined as a function of creep rupture time which was obtained from each creep rupture curve. The creep strain equations were able to express the creep deformation behavior of each test material with a satisfactory accuracy for a wide range of temperature and stress.