Nauka ta progres transportu (Aug 2020)
MATHEMATICAL PREDICTION OF THE PROPERTIES OF SUPERALLOYS
Abstract
Purpose. The purpose of this work is to obtain predictive regression models, with the help of which it is possible to adequately calculate the mechanical properties of heat-resistant nickel alloys, without conducting preliminary experiments. Methodology. Industrial alloys for equiaxed casting of domestic and foreign production were selected for research. The values were processed by the least squares method with obtaining correlation dependences with obtaining mathematical equations of regression models that optimally describe these dependences. Findings. As a result of processing experimental data, the ratio of alloying elements Kg¢ was proposed for the first time, which can be used to assess the mechanical properties, which takes into account the complex effect of the alloy main components. Since the dimensional mismatch of the lattice parameters is associated with the degree of concentration solid solution hardening of the γ- and γ′-phases, the efficiency of precipitation hardening of the alloy, the creep rate, and other properties, the Kg¢ ratio makes it possible to relate these properties to multicomponent systems. Regression models are presented, with the help of which it is possible to calculate the dimensional mismatch, strength, heat resistance, the amount of g¢ phase and the density of alloys with high accuracy. The regularities of the influence of the composition on the properties of equiaxed heat-resistant nickel alloys are established. It is shown that for multicomponent nickel systems, it is possible to predict with high reliability misfit, which has a significant effect on the strength characteristics of alloys of this class. For heat-resistant nickel alloys, a decrease in the misfit value is accompanied by a decrease in the number of elements in the g-solid solution at a value of Kg¢ = 1.5–2. However, an increase in Kg¢ greater than 2 is accompanied by an increase in misfit, since the volume fraction of g¢-forming elements significantly increases and begins prevail. A correlation has been established between the specific density and the average atomic mass of the alloys. Originality. It is shown that with an increase in the atomic mass, the specific density of alloys increases, since elements with a high atomic mass, which increase the specific density, belong to the elements that predominantly strengthen the g-solid solution and do not have a noticeable effect on the intermetallic hardening of alloys. Practical value. A promising and effective direction is shown in solving the problem of predicting the main characteristics that affect the complex of service properties of alloys both in the development of new heat-resistant nickel alloys and in the improvement of the compositions of well-known industrial brands of this class.
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