Model for time-to-fracture determination of low-alloyed steel under creep conditions

Abstract

Structural integrity of power plant component is usually estimate by its residual service life. Input data for component residual life estimation exposed to high-temperature creep is the creep strength of material (time dependent strength), after particular service period. Creep strength is usually obtained by statistical treatment of experimental data, and it decreases during service time due to degradation of microstructure. Since the creep resistance decreases with time due to microstructure degradation, it is essential for practice to use microstructural parameters in order to define statistically the changes in the creep resistance, which in turn enables to follow the physical significance of these changes. Due to a considerable scatter in the creep data, treatment by statistical analysis of the physically significant parameters is a problem that, to date has not been satisfactorily solved. One of attempt to overcome the lack of all data, which were required for previous analyses and estimation of service resources/service life, is done in this paper. Kinetic process has to be defined by the rate of process or by time for which such process will cause the rupture, instead of creep strength. Thus, the time to fracture of the component subjected to a high-temperature creep is determined due the kinetic theory of strength (model Zurkov) and using the microstructural parameters as an input data.