EXPERIMENTAL INVESTIGATION ON VERY-HIGH-CYCLE FATIGUE OF GCr15 STEEL

Attempts are made on revealing the very-high cycle fatigue behavior and fatigue mechanism of high strength steels. GCr15 steel was used as testing material and rotating bending fatigue test was adopted. The fractography of fatigue failure was observed by optical microscopy and scanning electron microscopy. The observations shows that, for the number of cycles to fatigue failure between 10~6 and 4×10~8 cycles, fatigue cracks mostly initiated in the interior of specimen and originated at non-metallic inclusions. The results indicate that the fatigue life of specimens with crack origin at the interior of specimen is longer than that with crack origin at specimen surface. The experimental results and the fatigue mechanism were further analyzed in terms of fracture mechanics and fracture physics.