Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Jtekt Corporation

Nippon Steel Sg Wire Co., Ltd.

Denso Corporation

Nhk Spring Co., Ltd.

Komatsu Corporation

Isuzu Motors Limited

Aisin Corporation

Sintokogio, Ltd.

Aoyama Seisakusho Co., Ltd.

Yutaka Neishi

Naoki Matsui

Takahisa Suzuki

Takashi Sada

Kohei Kanetani

Hitoshi Matsumoto

Tomohiro Yamashita

Masashi Higashida

Tatsuro Ochi

Tatsuya Koyama

Shoichi Suzuki

Shinya Teramoto

Kei Miyanishi

Daisuke Hirakami

Shuji Kozawa

Taizo Makino

Keisuke Chiba

Michimasa Aono

Akira Shiga

Tatsuya Hasegawa

Yoshihiro Tanimura

Kouji Morita

Makoto Egashira

Tetsushi Chida

Takashi Fujita

Takahiro Okada

Shingo Yamasaki

Fumio Takahashi

Makoto Kosaka

Hidekazu Sueno

Satoru Mineta

Hiroki Narumiya

Shigekazu Nishimoto

Sadanori Horikami

Toshimasa Itou

Mitsuhiro Kondo

Naoyuki Sashima

Akihisa Obata

Shoji Hori

Kazuo Maeda

Suguru Yoshida

Shinichirou Kashiwagi

Masashi Sakamoto

Yuji Kobayashi

Takashi Noda

Hideo Kanisawa

Junichi Kodama

Masato Yuya

Naomi Kobayashi

Eiji Amada

Tadashi Nishiwaki

Yorimasa Tsubota

Wataru Nagai

Tomomitsu Fukuoka

Osamu Kada

Toshimasa Ito

Kazuoki Shibuya

Hirohito Eto

Takahiro Shimano

Junji Tanaka

Naoki Takabayashi

Yoichi Oi

Kouji Oosato

Ryoji Nishijima

Mamoru Hatano

Takafumi Amata

Yoshitomi Yamada

Kazutaka Aoyama

Ryoko Inagaki

Naoyuki Sano

Hideaki Sugiura

Takanari Hamada

Takefumi Yano

Hiroki Uekita

Toshikazu Saitou

Tetsurou Hirano

Tetsuya Hironaka

There is provided a carburized bearing that is excellent in rolling contact fatigue life with a change in structure under a hydrogen-generating environment. In the carburized bearing, a chemical composition of a core portion 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. A proportion of a total area of CaO—CaS—MgO—AlOcomposite oxides with respect to a total area of oxides in the carburized leaping 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.

Carburized bearing

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

A damper spring which has an excellent fatigue limit is provided. A chemical composition of the damper spring according to the present embodiment contains in mass %, C: 0.50 to 0.80%, Si: 1.20 to less than 2.50%, Mn: 0.25 to 1.00%, P: 0.020% or less, S: 0.020% or less, Cr: 0.40 to 1.90%, V: 0.05 to 0.60%, and N: 0.0100% or less, with the balance being Fe and impurities. In the damper spring, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 5000 to 80000 pieces/μm.

Damper spring

A valve spring which has an excellent fatigue limit is provided. A chemical composition of the valve spring according to the present embodiment contains, in mass %, C: 0.50 to 0.80%, Si: 1.20 to less than 2.50%, Mn: 0.25 to 1.00%, P: 0.020% or less. S: 0.020% or less: Cr: 0.40 to 1.90%, V: 0.05 to 0.60%, Ca: 0.0001 to 0.0050%, and N: 0.0100% or less, with the balance being Fe and impurities. In the valve spring, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 5000 to 80000 pieces/μm, and a numerical proportion of Ca sulfides with respect to a total number of oxide-based inclusions and sulfide-based inclusions is 0.20% or less.

Valve spring

A damper spring having an excellent fatigue limit is provided. A damper spring according to the present embodiment includes a nitrided layer formed in an outer layer, and a core portion that is further inward than the nitrided layer. The chemical composition of the core portion consists of, in mass %, C: 0.53 to 0.59%, Si: 2.51 to 2.90%, Mn: 0.70 to 0.85%, P: 0.020% or less, S: 0.020% or less, Cr: 1.40 to 1.70%, Mo: 0.17 to 0.53%, V: 0.23 to 0.33%, Cu: 0.050% or less, Ni: 0.050% or less, Al: 0.0050% or less, Ti: 0.050% or less, N: 0.0070% or less, and Nb: 0 to 0.020%, with the balance being Fe and impurities. In the core portion, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 pieces/μm.

A steel material has a chemical composition which consists of, in mass %, C: 0.15 to 0.30%, Si: 0.02 to 1.00%, Mn: 0.20 to 0.80%, P: 0.020% or less, S: 0.028% or less, Cr: 0.80 to 1.50%, Mo: 0.08 to 0.40%, V: 0.10 to 0.40%, Al: 0.005 to 0.060%, N: 0.0150% or less, O: 0.0030% or less, and the balance: Fe and impurities, and satisfies Formulae (1) and (2), in which, at a cross section parallel to the axial direction of the steel material for a steel piston, the number of Mn sulfides is 100.0 per mmor less, the number of coarse Mn sulfides having an equivalent circular diameter of 3.0 μm or more is in a range of 1.0 to 10.0 per mm, and the number of oxides is 15.0 per mmor less.0.42≤Mo+3V≤1.50  (1)V/Mo≥0.50  (2)

Steel material for steel piston

There is provided a steel material that has a high critical working ratio in cold forging and has a high fatigue strength and an excellent hydrogen embrittlement resistance when the steel material is formed into a carburized-steel component. The steel material according to the present embodiment has a chemical composition that contains, in mass %, C: 0.07 to 0.13%, Si: 0.15 to 0.35%, Mn: 0.60 to 0.80%, S: 0.005 to 0.050%, Cr: 1.90 to 2.50%, B: 0.0005 to 0.0100%, Ti: 0.010 to less than 0.050%, Al: 0.010 to 0.100%, Ca: 0.0002% to 0.0030%, N: 0.0080% or less, P: 0.050% or less, and O: 0.0030% or less, with the balance being Fe and impurities, and satisfies Formula (1) to Formula (5) described in the specification.

Steel material

A track link which is a tracked undercarriage component is made of a steel having a specific component composition, and includes a high hardness portion having a hardness of HRC 57 or more and HRC 60 or less, and a low hardness portion. The high hardness portion includes a first matrix including a martensite phase and a residual austenite phase, and first nonmetallic particles dispersed in the first matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a MCcarbide. The low hardness portion includes a second matrix including a martensite phase, and second nonmetallic particles dispersed in the second matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN, and it does not include a MCcarbide.

Tracked undercarriage component, and method for producing the same

A valve spring includes a nitrided layer, and a core portion that is further inward than the nitrided layer. A chemical composition of the core portion consists of, in mass %, C: 0.53 to 0.59%, Si: 2.51 to 2.90%, Mn: 0.70 to 0.85%, P: 0.020% or less, S: 0.020% or less, Cr: 1.40 to 1.70%, Mo: 0.17 to 0.53%, V: 0.23 to 0.33%, Ca: 0.0001 to 0.0050%, Cu: 0.050% or less, Ni: 0.050% or less, Al: 0.0050% or less, Ti: 0.050% or less, and N: 0.0070% or less, with the balance being Fe and impurities. In the core portion, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 per μm, and in the core portion, a numerical proportion of Ca sulfides with respect to a total number of oxide-based inclusions and sulfide-based inclusions is 0.20% or less.

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 steel wire which has an excellent fatigue limit when made into a spring is provided. A chemical composition of the steel wire according to the present embodiment consists of, in mass %, C: 0.53 to 0.59%, Si: 2.51 to 2.90%, Mn: 0.70 to 0.85%, P: 0.020% or less, S: 0.020% or less, Cr 1.40 to 1.70%, Mo: 0.17 to 0.53%, V: 0.23 to 0.33%, Cu: 0.050% or less, Ni: 0.050% or less, Al: 0.0050% or less, Ti: 0.050% or less, N: 0.0070% or less, Ca: 0 to 0.0050%, and Nb: 0 to 0.020%, with the balance being Fe and impurities. In the steel wire, a number density of V-based precipitates having a maximum diameter ranging from 2 to 10 nm is 500 to 8000 pieces/μm.

Steel wire

A bearing steel part having a predetermined chemical composition, in which the number density of oxide particles having an equivalent circle diameter of 5 &#x3bc;m or more, and containing CaO, AlOand SiO, such that the content ratio of AlOwith respect to the total mass of CaO, AlO, and SiOis 50% by mass or more, is 3.0/cmor less in an arbitrary cross section of the part, and in which the Vickers hardness at a depth of 50 &#x3bc;m from a rolling surface is 750 or more, and in which the compressive residual stress at the rolling surface is 900 MPa or more. Also provided is a steel bar for a bearing steel part that is suitable for obtaining the foregoing bearing steel part.

Bearing steel component, and steel bar for bearing steel component

There is provided a spring steel including predetermined chemical composition, in which ([Ti mass %]&#x2212;3.43&#xd7;[N mass %])/[S mass %]&#x3e;4.0, and [Ni mass %]+[Cu mass %]&#x3c;0.75 are satisfied, and an appearance frequency of MnS is less than 20% among inclusions having an equivalent circle diameter of 1 &#x3bc;m or more which are observed at a &#xbc; position of a diameter from a surface.

Spring steel

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

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Tokyo, Japan

Yutaka Neishi