Rolling contact fatigue characteristics of a ball made of newly developed bearing steel with addition of Si and Mo

Recent rolling bearings have been used under the severe condition in many machines. For this trend, the vacuum melt to reduce the inclusion and some special heat treatments have been applied to the bearing steel for improving the rolling fatigue characteristics. While, the new development of bearing steel itself is required for the greater improvement in the fatigue characteristics. In this report, a newly developed bearing steel ball with rich amount of Si and Mo and the conventional bearing steel SUJ2 ball were fatigue-tested using a dynamic load type and a static load type rolling bearing fatigue testing machines. The rolling fatigue fives of these new and conventional steel balls were compared with each other, and were discussed considering the measured results of the hardness, residual stress, full width at half maximum and retained austenite during the fatigue process, and also of the initial carbide grain size, crush load and so on. It was consequently confirmed that the newly developed bearing steel ball has much longer rolling fatigue life comparing with the conventional one.