FATIGUE BEHAVIOR OF NOTCHED LOW-ALLOY STEEL SPECIMENS SUBJECTED TO CONVENTIONAL ANO SEVERE SHOT PEENING TREATMENTS

Notched specimens with a stress concentration factor common in many structural components have been subjected to different shot peening processes with a variety of peening parameter combinations. The applied treatments include shot peening with three different Almen intensities commonly used for low alloy steels and also severe shot peening aimed to generate a nanograined layer over the specimens’ surface. This severe shot peening process uses peening parameters essentially different from conventional ones. Roughness and X-ray diffraction measurements have been carried out to characterize the treated specimens. Rotating bending fatigue tests are performed to evaluate the effect of each treatment on specimens’ fatigue strength. Fracture surfaces have been then observed by scanning electron microscopy. The results indicate considerable improvement of fatigue life for severely shot peened specimens in spite of their very high surface roughness.