High-cycle fatigue properties of two C70S6 steels without and with Ti in steel ( % : 0. 69C-0. 034V- < 0. 005Ti-0. 015N and 0. 72C-0. 036V-0. 023Ti-0. 014N) for connecting rod of fracture splitting have been studied by using rotating-bending fatigue test method. Results show that all fatigue cracks initiated at matrix of surface of specimen
and the high-cycle fatigue properties are affected by micro-structure especially by interlamellar spacing of pearlite ; the interlainellar spacing of pearlite in the steel C70S6 containing 0. 023% Ti is larger than that in the Ti-free steel C70S6 in which there is coarse ( Ti
V) ( C
N) precipitates
therefore the fatigue properties of 0. 023%Ti steel are lower that that of Ti-free steel.