| 摘要 |
PROBLEM TO BE SOLVED: To provide a rolled bearing steel material with excellent rolling fatigue life.SOLUTION: The carburized bearing steel material has a chemical composition including specific amounts of C, Si, Mn, P, S, Al, Cr, N and O, and the balance Fe and impurities, in which predicted √AREAof oxide and predicted √AREAof sulfide in 30,000 mm, which are obtained by performing measurement of maximum oxide diameter and maximum sulfide diameter in a length-directional vertical section 100 mmwith respect to 30 points thereof followed by calculation by means of extremal statistics processing, are 50 μm or less and 60 μm or less respectively, and the average aspect ratio of maximum oxide and maximum sulfide measured at the 30 points is 5.0 or less. The average composition of maximum oxide at the 30 points is composed of any one of specific 2-element to 4-element oxides with the contents being CaO: 2.0-20%, MgO: O-20%, SiO: 0-10%, and the balance AlO, and the average composition of maximum sulfide at the 30 points is composed of a 1-element sulfide with the content being CaS: 100%, or a specific 2-element or 3-element sulfide with CaS≥1.0%, MgS: 0-20%, and the balance MnS. The steel material may include specific amounts of Mn, Ni instead of a part of Fe. |
