Prediction of creep and long-term strength of material using a leader sample under ductile fracture conditions

A method has been developed for predicting creep and long-term strength based on data on the behavior of a previously tested sample (leader sample, prototype) under ductile fracture conditions. It is assumed that the material, when loaded, does not have instantaneous plastic deformation and the first stage of creep, and the incompressibility hypothesis is satisfied for it. It is shown that if for a leader sample the creep curve at constant stress and the time until its failure are known, then to obtain a diagram of the rheological deformation and long-term strength of the material at other stress values it is enough to know only the initial (at the initial moment of time) minimum creep strain rate of the samples for these voltage values. The adequacy of the developed method was checked with experimental data during tension of samples made of corrosion-resistant steel grade 12X18H10T at a temperature of 850$^{\circ}$С and samples from a titanium alloy at a temperature of 600$^{\circ}$С, as well as during tension and torsion of samples from the D16T alloy at a temperature of 250$^{\circ}$С. It is shown that the prediction results do not depend on the choice of the leader sample from a number of samples tested at different voltages. The possibility of using the developed method in conducting experimental studies of materials under conditions of creep up to their destruction is discussed.