The isostress extrapolation of creep rupture data

Abstract Experiments were done on a total of ten heats of various ferritic steels to assess the applicability of the so-called isotress method to the extrapolation of creep rupture data. Creep tests were accelerated by elevating the testing temperatures while maintaining the initial stress constant. A straight line plot of the logarithm of the rupture time against temperature was obtained, which could be extrapolated with reasonable accuracy by a factor of up to 100 in time. This was found for both new material and material removed from long-time service at elevated temperatures.