Research the influence of surface hardening on the endurance limit of cylindrical specimens from various steels on the residual stresses of reference specimen

Research is devoted to studying the possibility of forecasting the endurance limit of cylindrical specimens of various diameter (10-50 mm) from steels 20, 45, 40H, 30HGSA with circular cuts of semicircular profile of 0,3 mm radius after advancing superficial plastic deformation (pneumo - and hydroshot-blasting processing) on the residual stresses (initial deformations) of the reference specimens (the plug with diameter of 51,5х45 mm) hardened simultaneously with smooth specimens. It is established that the compressive residual stresses calculated in smooth specimens with a diameter of 10-50 mm on initial deformations of reference specimen, slightly (to 10%) differs from defined experimentally. By the method developed earlier with use of the average integral residual stresses criterion the endurance limits increments of hardened specimens with cuts have been calculated. It is established that calculated values of endurance limits increments under bending in a case of symmetric cycle for specimens with cuts differ from experimental no more, than for 11%.