Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Nippon Steel Sg Wire Co., Ltd.

Other

Nhk Spring Co., Ltd.

Toyoda Koki Kabushiki Kaisha

Aisin Corporation

Tatsuro Ochi

Takashi Fujita

Manabu Kubota

Hideo Kanisawa

Yutaka Neishi

Shoichi Suzuki

Shinya Teramoto

Shuji Kozawa

Masayuki Hashimura

Michimasa Aono

Koji Tanabe

Yuji Kawauchi

Kiichiro Tsuchida

Fumio Takahashi

Kei Miyanishi

Ken-ichiro Naito

Masayoshi Saga

Yoshiro Koyasu

Hajime Saitoh

Shigekazu Nishimoto

Satoru Mineta

Kenichiro Naito

Joji Tamura

Mitsuhiro Kondo

Hiroshi Hagiwara

Toshiyuki Saito

Koji Nishi

Isashi Kashiwagi

Kazuyuki Ichikawa

Atsushi Mizuno

Atsushi Murakami

Koji Adachi

Masao Ishida

Yukio Noguchi

Toshihiko Takahashi

Ryuichi Seki

Takayuki Kisu

Yuji Inagaki

Takashige Nagato

Shuuji Kozawa

Fusao Ishikawa

Kouichi Yamazaki

Yoichi Oi

Naoki Takabayashi

Junji Tanaka

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 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.

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

This invention provides a forging steel excellent in forgeability, which forging steel comprises, in mass %, C: 0.001 to less than 0.07%, Si: 3.0% or less, Mn: 0.01 to 4.0%, Cr: 5.0% or less, P: 0.2% or less, S: 0.35% or less, Al: 0.0001 to 2.0%, N: 0.03% or less, one or both of Mo: 1.5% or less (including 0%) and Ni: 4.5% or less (including 0%), and a balance of iron and unavoidable impurities; wherein Di given by the following Equation (1) is 60 or greater:=5.41&#xd7;(Si)&#xd7;(Mn)&#xd7;(Cr)&#xd7;(Mo)&#xd7;(Ni)&#xd7;(Al)&#x2003;&#x2003;(1)

Forging steel

This case hardening steel has a chemical composition including, by mass %: C: 0.1 to 0.6%; Si: 0.02 to 1.5%; Mn: 0.3 to 1.8%; P: 0.025% or less; S: 0.001 to 0.15%; Al: over 0.05 to 1.0%; Ti: 0.05 to 0.2%; N: 0.01% or less; and O: 0.0025% or less, and further including, by mass %, one or more of Cr: 0.4 to 2.0%, Mo: 0.02 to 1.5%, Ni: 0.1 to 3.5%, V: 0.02 to 0.5%, and B: 0.0002 to 0.005%, and the balance consisting of iron and unavoidable impurities.

Case hardening steel, carburized component, and manufacturing method of case hardening steel

The present invention provides spring use heat treated steel which is cold coiled, can achieve both sufficient atmospheric strength and coilability, has a tensile strength of 2000 MPa or more, and can improve the performance as a spring by heat treatment after spring fabrication, that is, high strength spring-use heat treated steel characterized by containing, by mass %, C: 0.45 to 0.9%, Si: 1.7 to 3.0%, and Mn: 0.1 to 2.0%, restricting N: to 0.007% or less, having a balance of Fe and unavoidable impurities, and satisfying, in terms of the analyzed value of the extracted residue after heat treatment, [amount of Fe in residue on 0.2 &#x3bc;m filter/[steel electrolysis amount]&#xd7;100&#x2266;1.1.

High strength spring-use heat treated steel

A case hardening steel includes by mass %, C: 0.1% to 0.5%, Si: 0.01% to 1.5%, Mn: 0.3% to 1.8%, S: 0.001% to 0.15%, Cr: 0.4% to 2.0%, Ti: 0.05% to 0.2%, Al: limited to 0.2% or less, N: limited to 0.0050% or less, P: limited to 0.025% or less, O: limited to 0.0025% or less, and the balance of Fe and inevitable impurities, wherein the number d of sulfide having an equivalent circle diameter more than 5 &#x3bc;m per 1 mmand a mass percentage [S] of S satisfy: d&#x2266;500&#xd7;[S]+1.

Case hardening steel and manufacturing method thereof

In the steel for a surface layer hardening which is treated with carburizing in a temperature range of 800&#xb0; C. to 900&#xb0; C., chemical composition thereof contains, by mass %, C: 0.10% to 0.60%, Si: 0.01% to 2.50%, Mn: 0.20% to 2.00%, S: 0.0001% to 0.10%, Cr: 2.00% to 5.00%, Al: 0.001% to 0.50%, N: 0.0020% to 0.020%, P: 0.001% to 0.050%, and O: 0.0001% to 0.0030%; the remaining portion thereof includes Fe and unavoidable impurities; and the total amount of Cr, Si, and Mn satisfies, by mass %, 2.0&#x2266;Cr+Si+Mn&#x2266;8.0.

Surface layer-hardened steel part and method of manufacturing the same

The present invention provides a gear, continuously variable transmission, constant velocity joint, hub, or other steel part superior in surface fatigue strength compared with the past and method of production of the same, that is, provides a carbonitrided induction hardened steel part made of steel comprised of a specific composition of chemical ingredients and carbonitrided, then treated by induction hardening, the steel part characterized in that a surface N concentration is 0.1 to 0.8 mass %, a sum of an N concentration and C concentration is 1.0 to 2.0 mass %, an amount of surface residual austenite is less than 15 vol %, a depth of the incompletely hardened layer from the surface is less than 5 &#x3bc;m, and a surface X-ray diffraction half width is 6.0 degrees or more, and a method of production of the same.

Carbonitrided induction hardened steel part superior in surface fatigue strength at high temperature and method of production of same

This invention provides a case-hardening steel excellent in cold forgeability and low carburization distortion property that exhibits low deformation resistance and high limit compressibility when cold, namely, a case-hardening steel excellent in cold forgeability and low carburization distortion property comprising, in mass %, C: 0.07% to 0.3%, Si: 0.01% to 0.15%, Mn: 0.1% to 0.7%, P: 0.03% or less, S: 0.002% to 0.10%, Al: 0.01% to 0.08%, Cr: 0.7% to 1.5%, Ti: 0.01% to 0.15%, B: 0.0005% to 0.005%, N: 0.008% or less, and the balance of Fe and unavoidable impurities, and having a metallographic structure comprising 65% or greater of ferrite and 15% or less of bainite.

Case-hardening steel excellent in cold forgeability and low carburization distortion property

A steel material for a high strength constant velocity joint intermediate shaft is provided. The steal material may preferably contain C: 0.46 to 0.52%, Si: 0.6 to 0.8%, Mn: 0.7 to 0.9%, S: 0.01 to 0.05%, Mo: 0.3 to 0.5%, B: 0.0005 to 0.005%, Al: 0.002 to 0.05%, and Ti: 0.02 to 0.09%, restricting N to 0.007% or less, Cr to 0.15% or less, and P to 0.02% or less. A structural percentage of bainite+martensite may be provided which is 40% or more. The steal material may have a hardness of 250 HV to 340 HV. A high strength constant velocity joint intermediate shaft made of that steel material may be provided which has a spline-vanishing part with a surface hardness of about 610 HV to 750 HV, and a ratio t/r of an effective hardened layer depth t and radius r of 0.35 to 0.55, having a flat part with a surface hardness of about 630 HV to 770 HV and a ratio t/r of 0.55 to 1.0, and having a core hardness of about 250 HV to 340 HV.

Steel material for high strength constant velocity joint intermediate shaft and high strength constant velocity joint intermediate shaft

A bar or wire product for use in cold forging, characterized in that it comprises a steel having the chemical composition, in mass %: C: 0.1 to 0.6%, Si: 0.01 to 0.5%, Mn: 0.2 to 1.7%, S: 0.001 to 0.15%, Al: 0.015 to 0.05%, N: 0.003 to 0.025%, P: 0.035% or less, O: 0.003% or less and balance: Fe and inevitable impurities, and it has, in the region from the surface thereof to the depth of the radius thereof&#xd7;0.15, a structure wherein ferrite accounts for 10 area % or less and the balance is substantially one or more of martensite, bainite and pearlite, and the average hardness in the region from the depth of the radius thereof&#xd7;0.5 to the center thereof is less than that of the surface layer thereof by 20 or more of HV; and a method for producing the bar or wire product. The bar or wire product is excellent in the ductility after spheroidizing and thus allows the prevention of occurrence of cracks in a steel product during cold forging, which has conventionally been a problem in manufacturing structural parts for a machine by cold forging.

Steel bar or wire rod for cold forging and method of producing the same

A case hardening steel having good-grain coarsening prevention properties during carburization. The steel comprises, by weight, 0.1 to 0.4%. C, 0.02 to 1.3% Si, 0.3 to 1.8% Mn, 0.001 to 0.15% S, 0.015 to 0.04% Al, 0.005 to 0.04% Nb, 0.006 to 0.020% N, one, two or more selected from 0.4 to 1.8% Cr, 0.02 to 1.0% Mo, 0.1 to 3.5% Ni, 0.03 to 0.5% V, and in which P is limited to not more than 0.025%, Ti is limited to not more than 0.010%, and O is limited to not more than 0.0025%, with the balance being iron and unavoidable impurities, the steel being characterized in that, following hot rolling, the steel has a Nb(CN) precipitation amount of not less than 0.005% and an AlN precipitation amount that. is limited to not more than 0.005%.

Case hardened steel excellent in the prevention of coarsening of particles during carburizing thereof, method of manufacturing the same, and raw shaped material for carburized parts

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Tokyo, Japan

Tatsuro Ochi