Vol.3, No1, 2003, pp. 23-30
UDC 620.169.1:669.15-194.2

Statistical regression model for estimation of long-term strength of material exposed to high-temperature creep using microstructurally dependent parameters is presented. Microstructural parameters are obtained by kinetic theory of strength (Zurkov's model). Structural integrity of component is usually determined by estimation of material residual life for unchanged service conditions. Input data for residual-life estimation is the creep strength of the material (time dependent strength) after the given service period. Creep strength is determined by statistical treatment of experimental data and it decreases during service time due to degradation of microstructure. Thus, the adequate statistical approach based on micro-structural dependent parameters has to be developed in order to estimate the creep strength change during service life. This approach is based on the physics, connected with  microstructural degradation processes during creep. Anyhow, the application of statistical regression model has not been successful because of significant scatter of experimental results for the correlation of the creep strength change and microstructural parameters during the service time. A new approach for solving problems related to the regression model is proposed in this paper.

Keywords: low-alloy steel, creep, long-term strength, microstructure