ROLLING BEARING AND ITS MANUFACTURING METHOD

摘要

On the contact surface of the rolling bearing part made of alloy steel containing appropriate amounts of Cr and Mo, the C+N content is 0.9 to 1.4 mass % and the area ratio of carbide is 10% or less. At the depth of 1% of the diameter of the rolling element from the contact surface, the hardness is 720 to 832 in Hv, the amount of retained austenite is 20 to 45 volume %, and the compressive residual stress is 50 to 300 Mpa. At the depth of 1 to 3% of the diameter of the rolling element from the contact surface, the average value of the prior austenite grain size is 20 μm or less and the maximum value of the prior austenite grain size is 3 times or less the average value, and the hardness of the core portion is 400 to 550 in Hv.

主权项

1. A rolling bearing comprising an inner ring, an outer ring and rolling elements provided therebetween in a rollable manner,
wherein at least one of the inner ring, the outer ring and the rolling elements is made of an alloy steel containing: 0.10 to 0.30 mass % of C, 0.2 to 0.5 mass % of Si, 0.2 to 1.2 mass % of Mn, 2.6 to 4.5 mass % of Cr, 0.1 to 0.4 mass % of Mo, 0.20 mass % or less of Ni, 0.20 mass % or less of Cu, 0.020 mass % or less of S, 0.020 mass % or less of P, and 12 mass ppm or less of 0, the balance being Fe and inevitable impurities, a surface thereof is carburized or carbonitrided, and C+N content on the surface that contacts a counterpart surface during operation is 0.9 to 1.4 mass %, an area ratio of carbide on the contact surface is 10% or less, at a depth of 1% of the diameter of the rolling element from the contact surface, the hardness is 720 to 832 in Hv, an amount of retained austenite is 20 to 45 volume %, and compressive residual stress is 50 to 300 Mpa, at a depth of 1 to 3% of the diameter of the rolling element from the contact surface, an average value of prior austenite grain size is 20 μm or less, and the maximum value of the prior austenite grain size is 3 times or less the average value, and the hardness of a core portion is 400 to 550 in Hv.