Abstract
To investigate the applicability of the residual stress model used for the fatigue fracture surface of high hardened material SKH51 to the middle and low hardened materials, the residual stresses on the fatigue fracture surfaces of the quench-and-tempered SK-5 or SNCM439 and the annealed S15C were examined. The results obtained are summarized as follows. The residual stress on the fatigue fracture surfaces σr was found to be given by the sum of the same three components as that for the high hardened material; the tensile stress component, σr1, the compression stress component -σr2 and the compression component -σr3. The contribution of -σr3 was especially large in the low stress intensity factor range, and the residual stress on the fracture surface showed various distributions due to the variations of -σr2 and -σr3.
