*10.26731/1813-9108.2018.2(58).34-40*

*The article considers the problems of determining residual stresses. Based on the work of the predecessors, it was concluded that there is a need for a calculation method for determining thermal residual stresses, since the existing non-destructive methods have low accuracy, while destructive methods increase the cost of producing low-rigidity parts and are not applicable at the design stage. The existing calculation methods of determination have a narrow specificity, therefore, in the work the residual stresses arising during heat treatment are studied in more detail, for calculation of which the non-stationary thermal field calculation results are needed. The main problem in the calculation of the thermal field is the determination of the heat transfer coefficient, since the values of the heat transfer coefficient depend on a significant number of non-stationary parameters, the change of which is difficult to predict. The determination of the heat transfer coefficient is complicated by the speed of the processes occurring during the heat treatment and by the significant number of factors. The values of the coefficient depend on these factors. Based on the literature review, it is difficult to calculate the heat transfer coefficient. Therefore, a calculation and experimental model of the thermal field and an algorithm that allows calculating the heat transfer coefficient by parametric identification using the experimental cooling curves are proposed. The suggested calculation-and-experimental model and the algorithm of parametric identification made it possible to obtain the dependence of the heat transfer coefficient on the surface temperature of the investigated workpiece. The obtained dependence of the heat transfer coefficient on the surface temperature of the workpiece has several stages of change. It is also important to note that the reference points of the obtained dependence are in good agreement with the existing liquid boiling regimes. Based on the dependence, the nonstationary thermal field and the epures of the thermal residual stresses are calculated, which have an error of no more than 5 %.*

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