Kobe Steel, Ltd.

Masaki Kaizuka

Yosuke Shindo

Tomoko Sugimura

Mutsuhisa Nagahama

Masaki Shimamoto

Tetsushi Deura

Sei Kimura

Manabu Fujita

Akihiro Owaki

A bearing component having increased rolling-contact fatigue life, the bearing component being made of a bearing steel that satisfies a predetermined chemical composition, and Si (boundary Si), Mn (boundary Mn), Cr (boundary Cr), Cu (boundary Cu), Ni (boundary Ni), and Mo (boundary Mo) included in a matrix phase region (boundary surface region) from the surface of spheroidized cementite to 20 nm away satisfy the formula:9.0&#x2266;1.4&#xd7;boundary Si+1.8&#xd7;boundary Mn+5.5&#xd7;boundary Cu+4.2&#xd7;boundary Ni+4.8&#xd7;boundary Cr+5.5&#xd7;boundary Mo.

Bearing steel excellent in rolling-contact fatigue properties and method for producing same

Provided is a bearing steel capable of exhibiting excellent cold workability in cold working that follows spheroidizing annealing and also capable of ensuring excellent abrasion resistance and rolling fatigue characteristics as a bearing member or the like. The bearing steel contains C: 0.9 to 1.10%, Si: 0.05 to 0.49%, Mn: 0.1 to 1.0%, P: not more than 0.05% (excluding 0%), S: not more than 0.05% (excluding 0%), Cr: 0.03 to 0.40%, Al: not more than 0.05% (excluding 0%), N: 0.002 to 0.025%, Ti: not more than 0.0030% (excluding 0%), and O: not more than 0.0025% (excluding 0%), with the remainder being iron and unavoidable impurities. The average aspect ratio of cementite is not more than 2.00, the average circle-equivalent diameter of cementite is 0.35 to 0.6 &#x3bc;m, and the number density of cementite having a circle-equivalent diameter of not less than 0.13 &#x3bc;m is not less than 0.45/&#x3bc;m.

Bearing steel

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 AlO, 30 to 50% of SiO, 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 &#x3bc;m or less; and a spheroidal cementite structure.

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

A bearing steel material which contains 0.8-1.1 mass % C, 0.15-0.8 mass % Si, 0.1-1.0 mass % Mn, 1.3-1.8 mass % Cr, up to 0.05 mass % P (0 mass % is excluded), up to 0.015 mass % S (0 mass % excluded), 0.0002-0.005 mass % Al, 0.0002-0.0020 mass % Ca, 0.0005-0.010 mass % Ti, up to 0.0080 mass % N (0 mass % is excluded), and up to 0.0025 mass % O (0 mass % is excluded). The steel material contains oxide inclusions which have an average composition that comprises, in terms of mass %, 20-50% CaO, 20-50% AlO, 20-70% SiO, and 3-10% TiO.

Bearing steel material with excellent rolling fatigue property and bearing part

Disclosed is a steel having high manufacturability and better rolling-contact fatigue properties. The steel contains C of 0.65% to 1.30%, Si of 0.05% to 1.00%, Mn of 0.1% to 2.00%, P of greater than 0% to 0.050%, S of greater than 0% to 0.050%, Cr of 0.15% to 2.00%, Al of 0.010% to 0.100%, N of greater than 0% to 0.025%, Ti of greater than 0% to 0.015%, and O of greater than 0% to 0.0025% and further contains iron and unavoidable impurities. Al-containing nitrogen compound particles dispersed in the steel have an average equivalent circle diameter of 25 to 200 nm, and Al-containing nitrogen compound particles each having an equivalent circle diameter of 25 to 200 nm are present in a number density of 1.1 to 6.0 per square micrometer.

Steel with excellent rolling-contact fatigue properties

This bearing steel material satisfies a predetermined elemental composition, and is characterized by having, in the region (boundary region) from the boundary surface of spheroidal cementite to a position at 20 nm away in a base material, no greater than 0.6% (excluding 0%) of Si (boundary Si), no greater than 0.10% (excluding 0%) of Ni (boundary Ni), no greater than 0.10% (excluding 0%) of Cu (boundary Cu), no greater than 0.03% (including 0%) of Mo (boundary Mo), no greater than 0.10% (excluding 0%) of Mn (boundary Mn), and no greater than 0.9% (excluding 0%) of Cr (boundary Cr), and the circularity coefficient of the spheroidized cementite being at least 0.80. The bearing steel material exhibits favorable cold-workability during the production of a bearing component by means of cold working.

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Kobe, Japan

Masaki Kaizuka