Bearing steel material with excellent rolling contact fatigue properties and a bearing part

摘要

Bearing steel material according to the present invention has: a properly adjusted chemical composition; an average chemical composition of oxide-inclusions which comprises 10 to 45% of CaO, 20 to 45% of Al2O3, 30 to 50% of SiO2, up to 15% (exclusive of 0) of MnO, and 3 to 10% of MgO, with the balance being unavoidable impurities; a maximum major axis diameter of the oxide inclusions in a longitudinal section of the steel material of 20 μm or less; and a spheroidal cementite structure.

主权项

1. A bearing steel material, comprising:
by mass%, from 0.8% to 1.1% of C; from 0.15% to 0.8% of Si; from 0.10% to 1.0% of Mn; up to 0.05%, excluding 0%, of P; up to 0.01%, excluding 0%, of S; from 1.3% to 1.8% of Cr; from 0.0002% to 0.005% of Al; from 0.0002% to 0.0010% of Ca; up to 0.0030%, excluding 0%, of O; and iron, wherein an average chemical composition of oxide-inclusions in the bearing steel material is, by mass%: from 10% to 45% of CaO; from 20% to 45% of Al2O3; from 30% to 50% of SiO2; up to 15%, excluding 0%, of MnO; and from 3% to 10% of MgO; a maximum major axis diameter of the oxide-inclusions in a longitudinal section of the bearing steel material is 20 μm or less; and the bearing steel material has a spheroidal cementite structure.