The effect of the residual stresses generated by surface finishing methods on the very high cycle fatigue behavior of matrix HSS

To investigate the fatigue properties of matrix high-speed tool steel (0.7C-0.1W-3Mo-2V) under very high cycle fatigue regimes, cantilever-type rotating bending fatigue tests were carried out on hour-glass shaped specimens in an air atmosphere at room temperature. The specimen surfaces were finished by grinding and cutting processes which give different surface compressive residual stresses. Both specimen treatments showed a clear duplex S-N curve, composed of three types of failure mode depending on the stress amplitude. A map of the appearance of failure modes relating stress amplitude to residual stress was proposed. The dependence of the S-N curve on a critical size of inclusion at the crack origin was demonstrated by the estimation of crack growth rate from the S-N data.