Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Jtekt Corporation

Sumitomo Electric Industries, Limited

Daisuke Hirakami

Makoto Okonogi

Tomohiro Yamashita

Yutaka Neishi

Shingo Yamasaki

Takahisa Suzuki

Takashi Sada

Toshimi Tarui

Kohei Kanetani

Tatsuya Koyama

Seiki Nishida

Masato Yamada

Toshiyuki Manabe

Katsuhito Oshima

Tetsushi Chida

Nariyasu Muroga

Shuichi Tanaka

Manabu Kubota

Masayuki Hashimura

Motoki Takasuga

Arata Iso

Tatsusei Tada

Susumu Sahara

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

This invention provides a high-strength PC steel wire having a chemical composition containing, in mass %, C: 0.90 to 1.10%, Si: 0.80 to 1.50%, Mn: 0.30 to 0.70%, P: 0.030% or less, S: 0.030% or less, Al: 0.010 to 0.070%, N: 0.0010 to 0.010%, Cr: 0 to 0.50%, V: 0 to 0.10%, B: 0 to 0.005%, Ni: 0 to 1.0%, Cu: 0 to 0.50%, and the balance: Fe and impurities. A ratio between the Vickers hardness (Hv) at a location (surface layer) that is 0.1D [D: diameter of steel wire] from the surface of the steel wire and the Vickers hardness (Hv) of a region on the inner side relative to the surface layer satisfies the formula [1.10&#x3c;Hv/Hv&#x2264;1.15]. An average carbon concentration in a region from the surface to a depth of 10 &#x3bc;m (outermost layer region) of the steel wire is 0.8 times or less a carbon concentration of the steel wire. The steel micro-structure in the region on the inner side relative to the outermost layer region contains, in area %, a pearlite structure: 95% or more. The tensile strength of the steel wire is 2000 to 2400 MPa. The method of producing this high-strength PC steel wire is simple, and the high-strength PC steel wire is excellent in delayed fracture resistance characteristics.

High-strength PC steel wire

This invention provides a high-strength PC steel wire having a chemical composition containing, in mass %, C: 0.90 to 1.10%, Si: 0.80 to 1.50%, Mn: 0.30 to 0.70%, P: 0.030% or less, S: 0.030% or less, Al: 0.010 to 0.070%, N: 0.0010 to 0.010%, Cr: 0 to 0.50%, V: 0 to 0.10%, B: 0 to 0.005%, Ni: 0 to 1.0%, Cu: 0 to 0.50%, and the balance: Fe and impurities. A ratio between the Vickers hardness (Hv) at a location (surface layer) that is 0.1D [D: diameter of steel wire] from the surface of the steel wire and the Vickers hardness (Hv) of a region on the inner side relative to the surface layer satisfies the formula [1.10&#x3c;Hv/Hv&#x2264;1.15]. The steel micro-structure in the region from the surface of the steel wire to 0.01D (outermost layer region) consists of, in area %, a pearlite structure: less than 80%, and the balance: a ferrite structure and/or a bainitic structure. The steel micro-structure in the region on the inner side relative to the outermost layer region contains, in area %, a pearlite structure: 95% or more. The tensile strength of the steel wire is 2000 to 2400 MPa. The method of producing this high-strength PC steel wire is simple, and the high-strength PC steel wire is excellent in delayed fracture resistance characteristics.

Provided is a high-carbon steel wire rod with excellent wire drawability, containing predetermined chemical components and the balance: Fe and impurities. In a cross-section perpendicular to a longitudinal direction, an area fraction of pearlite is equal to or more than 95% and equal to or less than 100%, an average block size of the pearlite is 10 &#x3bc;m to 30 &#x3bc;m and standard deviation of block size is 20 &#x3bc;m or less, and when Ceq.=C (%)+Si (%)/24+Mn (%)/6, a tensile strength is equal to or more than 760&#xd7;Ceq.+255 MPa and equal to or less than 760&#xd7;Ceq.+325 MPa, reduction of area in a tensile test is &#x2212;65&#xd7;Ceq.+96(%) or more, and standard deviation of the reduction of area is 6% or less.

High-carbon steel wire rod with excellent wire drawability

A steel wire for a non heat-treated mechanical part includes, as a chemical composition, by mass %, a predetermined amount of C, Si, Mn, Cr, Mo, Ti, Al, B, Nb, and V, and limited P, S, N, and O and a remainder of Fe and impurities; in which a structure includes, by volume %, a bainite of greater than or equal to 75&#xd7;[C %]+25, and a remainder of one or more of a ferrite and a pearlite when an amount of C is set to [C %] by mass %; when an average aspect ratio of a bainite block in a second surface layer area of the steel wire is set as R1, the R1 is greater than or equal to 1.2; when an average grain size of a bainite block in a third surface layer area of the steel wire is set to P&#x3bc;m, and an average grain size of a bainite block in a third center portion of the steel wire is set to P&#x3bc;m, the Psatisfies Expression (c), and the Pand the Psatisfy Expression (d), a standard deviation of a grain size of the bainite block in the structure is less than or equal to 8.0 &#x3bc;m; and a tensile strength is in a range of 800 MPa to 1600 MPa,&#x2264;20/1&#x2003;&#x2003;(c),&#x2264;0.95&#x2003;&#x2003;(d).

Wire rod for non heat-treated mechanical part, steel wire for non heat-treated mechanical part, and non heat-treated mechanical part

A wire rod for a steel cord has a wire diameter R of 3.5 mm to 8.0 mm, and includes, in a chemical composition, by mass %: C: 0.70% to 1.20%; Si: 0.15% to 0.60%; Mn: 0.10% to 1.00%; N: 0.0010% to 0.0050%; Al: more than 0% and 0.0100% or less; and a remainder of Fe and impurities, in which a surface part and a central part are included, a thickness of the surface part is 50 &#x3bc;m to 0.20&#xd7;R, the central part includes a pearlite structure in a proportion of 95% to 100% by area %, a C content of the surface part is 40% to 95% of a C content of the central part, and a ratio of a thickness of a lamellar cementite at a center of the thickness of the surface part to a thickness of a lamellar cementite in the central part is 95% or less, whereby high strength and workability can be achieved even after a finish drawing process and cracking or the like caused by a delamination phenomenon can be prevented.

Wire rod for high strength steel cord

A steel wire rod includes required amounts of chemical components and a remainder including Fe and impurities; in which the area ratio of pearlite in a cross section perpendicular to a longitudinal direction is 95% or more and a remainder includes a non-pearlite structure which includes one or more of a bainite, a degenerate pearlite, a proeutectoid ferrite and a proeutectoid cementite; the average block size of the pearlite is 15 &#x3bc;m to 35 &#x3bc;m and the area ratio of the pearlite having a block size of 50 &#x3bc;m or more is 20% or less; and the area ratio of a region where a lamellar spacing of the pearlite is 150 nm or less is 20% or less in a region within a depth from a surface of the steel wire rod of 1 mm or less.

High carbon steel wire rod and method for manufacturing same

A filament for a high strength steel cord has a wire diameter R of 0.1 mm to 0.4 mm, and includes, in a chemical composition, by mass %: C: 0.70% to 1.20%; Si: 0.15% to 0.60%; Mn: 0.10% to 1.00%; N: 0.0010% to 0.0050%; Al: more than 0% and 0.0100% or less; and a remainder of Fe and impurities, in which a surface part and a central part are included, a thickness of the surface part is 0.01&#xd7;R to 0.10&#xd7;R, the central part includes a pearlite structure in a proportion of 95% to 100% by area %, a C content of the surface part is 40% to 95% of a C content of the central part, and a ratio of a thickness of a lamellar cementite at a center of the thickness of the surface part to a thickness of a lamellar cementite in the central part is 95% or less, whereby high strength and workability can be achieved and cracking or the like caused by a delamination phenomenon can be prevented.

Filament for high strength steel cord

A steel wire according to an aspect of the present invention includes a predetermined chemical composition, in which a wire diameter R of the steel wire is 1.0 mm to 3.5 mm, a soft portion is formed along an outer circumference of the steel wire, the Vickers hardness of the soft portion is lower than that of a position of the steel wire at a depth of &#xbc; of the wire diameter R by Hv 30 or higher, the thickness of the soft portion is 5 &#x3bc;m to 0.1&#xd7;R mm, the metallographic structure of a center portion of the steel wire contains 95% to 100% of pearlite by area %, the average lamellar spacing of pearlite in a portion from a surface of the steel wire to a depth of 5 &#x3bc;m is less than that of pearlite at the center of the steel wire, the difference between the average lamellar spacing of pearlite in the portion from the surface of the steel wire to the depth of 5 &#x3bc;m and the average lamellar spacing of pearlite at the center of the steel wire is 3 nm to 60 nm, and the tensile strength is 1100 MPa or higher.

Steel wire

A filament according to an aspect of the present invention includes a predetermined chemical composition, in which a diameter r of the filament is 0.15 mm to 0.35 mm, a soft portion is formed along an outer circumference of the filament, the Vickers hardness of the soft portion is lower than that of a position of the filament at a depth of &#xbc; of the diameter r by Hv 50 or higher, the thickness of the soft portion is 1 &#x3bc;m to 0.1&#xd7;r mm, the metallographic structure of a center portion of the filament contains 95% to 100% of pearlite by area %, the average lamellar spacing of pearlite in a portion from a surface of the filament to a depth of 1 &#x3bc;m is less than that of pearlite at the center of the filament, the difference between the average lamellar spacing of pearlite in the portion from the surface of the filament to the depth of 1 &#x3bc;m and the average lamellar spacing of pearlite at the center of the filament is 2.0 nm or less, and the tensile strength is 3200 MPa or higher.

Filament

The present invention provides a wire rod with a composition at least including: C: 0.95-1.30 mass %; Si: 0.1-1.5 mass %; Mn: 0.1-1.0 mass %; Al: 0-0.1 mass %; Ti: 0-0.1 mass %; P: 0-0.02 mass %; S: 0-0.02 mass %; N: 10-50 ppm; O: 10-40 ppm; and a balance including Fe and inevitable impurities, wherein 97% or more of an area in a cross-section perpendicular to the longitudinal direction of the wire rod is occupied by a pearlite, and 0.5% or less of an area in a central area in the cross-section and 0.5% or less of an area in a first surface layer area in the cross-section are occupied by a pro-eutectoid cementite.

Wire rod, steel wire, and manufacturing method thereof

A steel which is excellent in delayed fracture resistance containing, by mass %, C: 0.10 to 0.55%, Si: 0.01 to 3%, and Mn: 0.1 to 2%, further containing one or more of Cr: 0.05 to 1.5%, V: 0.05 to 0.2%, Mo: 0.05 to 0.4%, Nb: 0.001 to 0.05%, Cu: 0.01 to 4%, Ni: 0.01 to 4%, and B: 0.0001 to 0.005%, and having a balance of Fe and unavoidable impurities, the structure being a mainly tempered martensite structure, the surface of the steel being formed with (a) a nitrided layer having a certain thickness range and a nitrogen concentration higher than the nitrogen concentration of the steel by 0.02 mass % or more and (b) a low carbon region having a certain depth range from the surface of the steel and having a carbon concentration of 0.9 time or less the carbon concentration of the steel.

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Tokyo, Japan

Daisuke Hirakami