US Patent 7703984 Rolling bearing

A rolling bearing comprises a roller, a roller shaft provided inwardly of the roller, and rolling elements provided between the roller and the roller shaft, the roller shaft having a nitrogen-rich layer and is configured such that its race surface, on which the rolling elements run, has not smaller than 11 in the JIS austenite grain size number and not smaller than HV653 in the Vickers hardness number, at both ends not greater than HV300, and at its core beneath a widthwise midpoint of the race surface not smaller than HV550.