Extrapolation of Creep Rupture Strength Diagrams for Heat-Resistant Materials

The efficiency of known approaches to predicting the creep rupture strength diagrams of heat-resistant materials at elevated temperatures is analyzed. Extrapolation results for long deformation terms with known Larson–Miller, Orr–Sherby–Dorn, Trunin, Manson–Haferd parametric methods, and the modified base diagram method are presented. Creep rupture strength characteristics were calculated on the basis of existing experimental life curves for heat-resistant materials. The reliability of calculations is corroborated by comparing with known experiments for 18Cr-12Ni-Mo and 1.25Cr-0.5Mo-Si steels. The advantages of the modified base diagram method for creep rupture strength prediction on large deformation databases are demonstrated. Mathematical models for extrapolation of creep rupture strength diagrams are examined in view of a limited number of experimental data and the nonfulfilment of the hypothesis of a single curve.