Прогнозирование предела выносливости поверхностно упрочненных сплошных цилиндрических образцов из стали 45 по остаточным напряжениям образца-свидетеля

Background. The discovery of connection between residual stresses of a reference specimen and the endurance limit of a simultaneously hardened part is an extremely topical task; its solution will make it possible to reduce expensive and prolonged fatigue tests. Materials and methods. To achieve the set task, the authors examined the possibility of using reference specimens, having a bush form with the diameter of 51,5×45 mm, in forecasting of the endurance limit of solid specimens made of steel 45 of various diameters (10-50 mm) with circular cuts of 0,3 mm radius and subject to hydro blasting treatment. Results. According to experimental measuring of residual stresses of reference specimens the authors determined initial deformations, which were used to calculate residual stresses in smooth specimens and then in specimens with cuts made after surface hardening. Conclusions. Using the average integral residual stresses criterion it is established that the calculated values of endurance limits increments under bending in case of a symmetric cycle of hardened specimens with cuts differ from the experimental ones less than 16 %. This result shows that reference specimens and the average integral residual stresses criterion can be used for endurance limit prediction for the parts made of steel 45 with the diameters 10-50 mm, hardened by hydro blasting treatment.