BEARING RING FOR BEARING

摘要

PROBLEM TO BE SOLVED: To minimize the quantities of Cr and Mo to make a bearing ring manufacturable with an inexpensive material while holding excellent quenching property, and ensure excellent rotating bearing performance by adding a specified quantity of boron to medium carbon alloy steel. SOLUTION: Arotating seat ball bearing 20 is formed of a single-line ball bearing having an outer ring 21, an inner ring 22 and a ball 23, which is of a type having a gear 22 on the inner surface side of the inner ring 2. The inner ring 22 is arranged on the inner surface side of the outer ring 21, and the ball 23 is charged between the semicircular sectional rolling surfaces 21a, 22a of the outer ring 21 and the inner ring 22. Medium carbon alloy steel is used for at least one material of the inner ring 22 and the outer ring 21. In this medium carbon alloy steel, 0.0010% or more and 0.0025% or less by chemical component % of B is included. By adding B in such a manner, excellent rolling fatigue characteristic, ring rotation crack fatigue characteristic and static crack strength can be ensured to the same degree as the use of SCM 445 even if the quantities of Cr and Mo are reduced more than in SCM 445.