Jtekt Corporation

Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Kohei Kanetani

Yutaka Neishi

Takashi Sada

Takahisa Suzuki

Tomohiro Yamashita

Tatsuya Koyama

Daisuke Hirakami

Shingo Yamasaki

Takahiro Shimano

Tetsuya Hironaka

A steel consists of, in mass %, C: 0.25 to 0.45%, Si: 0.10 to 0.50%, Mn: 0.40 to 0.70%, P: 0.015% or less, S: 0.005% or less, Cr: 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfies Formula (1) to Formula (4) described in the present specification, wherein: its microstructure is composed of ferrite and pearlite having a total area fraction of 5.0 to 100.0%, and a hard phase having a total area fraction of 0 to 95.0%; a proportion of a total area of CaO—CaS—MgO—AlOcomposite oxides with respect to a total area of oxides in the steel is 30.0% or more; and a number density of oxides having an equivalent circle diameter of 20.0 μm or more is 15.0 pieces/mmor less.

Steel

A core portion of the carbonitrided bearing component includes a chemical composition consisting of, in mass %, C: 0.15 to 0.45%, Si: 0.50% or less, Mn: 0.20 to 0.60%, P: 0.015% or less, S: 0.005% or less, Cr 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfying Formula (1) to Formula (4) described in the embodiment of the present specification. A concentration of C of its surface is, in mass %, 0.70 to 1.20%, a concentration of N of the surface is, in mass %, 0.15 to 0.60%, a Rockwell C-scale hardness HRC of the surface is 58 to 65, and in the core portion, an area ratio of an area of coarse V-based precipitates to a total area of V-based precipitates is 15.0% or less.

Carbonitrided bearing component

The steel material includes a chemical composition containing, in mass %, C: 0.15 to 0.45%, Si: 0.50% or less, Mn: 0.20 to 0.60%, P: 0.015% or less, S: 0.005% or less, Cr: 0.80 to 1.50%, Mo: 0.17 to 0.30%, V: 0.24 to 0.40%, Al: 0.005 to 0.100%, N: 0.0300% or less, O: 0.0015% or less, and the balance being Fe and impurities, and satisfying Formula (1) to Formula (4) described in Embodiment, wherein, in its microstructure, a total area fraction of ferrite and pearlite is 10.0% or more, and a proportion of a content of V (mass %) in electrolytic extraction residue to the content of V (mass %) in the chemical composition is 10.0% or less.

Steel material to be starting material of carbonitrided bearing component

A rolling sliding member includes a base part and a surface layer. The base part has a composition that includes 0.30 mass % to 0.45 mass % of carbon, 0.15 mass % to 0.45 mass % of silicon, 0.40 to 1.50 mass % of manganese, 0.60 mass % to 2.00 mass % of chromium, 0.10 mass % to 0.35 mass % of molybdenum, 0.20 mass % to 0.40 mass % of vanadium, and 0.005 mass % to 0.100 mass % of aluminum, and a remainder of iron and inevitable impurities. The surface layer is positioned around the base part. The surface layer has a Vickers hardness of 700 to 800 and a retained austenite content of 25 volume % to 50 volume %. The thickness of a grain boundary oxide layer satisfies Formula: thickness of grain boundary oxide layer&#x2264;equivalent diameter of rolling sliding member&#xd7;1.4&#xd7;10.

Rolling sliding member and method of producing the same, and rolling bearing including rolling sliding member

The steel material for a carburized bearing part according to the present invention contains, by mass %, C: 0.25 to 0.45%, Si: 0.15 to 0.45%, Mn: 0.40 to 1.50%, P: 0.015% or less, S: 0.005% or less, Cr: 0.60 to 2.00%, Mo: 0.10 to 0.35%, V: 0.20 to 0.40%, Al: 0.005 to 0.100%, Ca: 0.0002 to 0.0010%, N: 0.0300% or less and O: 0.0015% or less, with the balance being Fe and impurities, and satisfies Formulae (1) to (3).1.20&#x3c;0.4Cr+0.4Mo+4.5V&#x3c;2.75&#x2003;&#x2003;(1)A1/A2&#x3e;0.50&#x2003;&#x2003;(2)2.7C+0.4Si+Mn+0.45Ni+0.8Cr+Mo+V&#x3e;2.55&#x2003;&#x2003;(3)Formula (2) shows an area fraction of sulfides containing Ca in an amount of 1 mol % or more among sulfides having an equivalent circular diameter of 1 &#x3bc;m or more.

Steel material for carburized bearing part

Provided is a steel for carbonitrided bearing which excels in hardenability and also excels in toughness, wear resistance, and surface-originated flaking life after quenching and tempering. A steel for carbonitrided bearing of the present embodiment has a chemical composition containing, in mass %, C: 0.22 to 0.45%, Si: not more than 0.50%, Mn: 0.40 to 1.50%, P: not more than 0.015%, S: not more than 0.005%, Cr: 0.30 to 2.0%, Mo: 0.10 to 0.35%, V: 0.20 to 0.40%, Al: 0.005 to 0.10%, N: not more than 0.030%, and O: not more than 0.0015%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2).1.20&#x3c;0.4Cr+0.4Mo+4.5V&#x3c;2.60&#x2003;&#x2003;(1)2.7C+0.4Si+Mn+0.8Cr+Mo+V&#x3e;2.20&#x2003;&#x2003;(2)

Steel for carbonitrided bearing

Provided is a carbonitrided bearing part which has high hardenability and toughness, and is excellent in wear resistance and surface-originated flaking life. A carbonitrided bearing part of the present embodiment has a chemical composition containing, in mass %, C: 0.15 to 0.45%, Si: not more than 0.50%, Mn: 0.40 to 1.50%, P: not more than 0.015%, S: not more than 0.005%, Cr: 0.30 to 2.0%, Mo: 0.10 to 0.35%, V: 0.20 to 0.40%, Al: 0.005 to 0.10%, N: not more than 0.030%, and O: not more than 0.0015%, with the balance being Fe and impurities, and satisfying Formulae (1) and (2). At surface, C concentration is 0.7 to 1.2%, N concentration is 0.15 to 0.6%, and Rockwell hardness HRC is 58 to 65.1.20&#x3c;0.4Cr+0.4Mo+4.5V&#x3c;2.60&#x2003;&#x2003;(1)2.7C+0.4Si+Mn+0.8Cr+Mo+V&#x3e;2.20&#x2003;&#x2003;(2)

Carbonitrided bearing part

A bearing constituent member includes a base material including steel and a carbonitrided layer that is a surface layer on the steel, the steel including 0.3 to 0.45 mass % of carbon, 0.5 mass % or lower of silicon, 0.4 to 1.5 mass % of manganese, 0.3 to 2 mass % of chromium, 0.1 to 0.35 mass % of molybdenum, 0.2 to 0.4 mass % of vanadium, and a remainder of iron and unavoidable impurities. Surface Vickers hardness at a position at a depth of 50 &#x3bc;m from a surface of a rolling sliding surface is 700 to 800, internal hardness is 550 to 690 in terms of Vickers hardness, and an amount of residual austenite in a range from the surface to a depth of 10 &#x3bc;m is at least 30 vol %.

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Kashiba, Japan

Kohei Kanetani