Abstract
It is reported that a clean steel with low oxygen content is effective to improve the fatigue strength. In this paper, the bending fatigue tests of carburized gears of clean steel and ordinary steel with oxygen content of 5ppm and 8ppm, respectively, were carried out. The results as carburized are approximately same. The nonmartensitic layers which of thickness are 5 to 20μm are observed on the surface of the clean and ordinary steels. After removing the nonmartensitic layers by electropolishing, the fatigue strength of the clean steel gear is improved 28% higher than that of the ordinary steel gear.
