Kawasaki Steel Corporation

Jfe Steel Corporation

Other

Kusakabe Electric & Machinery Co.

Ntn Corporation

Jtekt Corporation

Takaaki Toyooka

Yuji Hashimoto

Osamu Kondo

Katsumi Yamada

Akira Yorifuji

Motoaki Itadani

Mitsuo Kimura

Takatoshi Okabe

Nobuki Tanaka

Masatoshi Aratani

Yoshikazu Kawabata

Masanori Nishimori

Koji Sugano

Yukio Miyata

Tomoya Koseki

Hideto Kimura

Kazukuni Hase

Takuya Nagahama

Osamu Furukimi

Saiji Matsuoka

Masahiko Morita

Takaaki Hira

Hiroshi Fujiwara

Shigeharu Ochi

Takashi Iwamoto

Kazuhiko Yoshida

Isao Hirai

Kunikazu Tomita

Toshiaki Amagasa

Akihiro Matsuzaki

Masao Goto

Toru Hayashi

Toshio Ohnishi

Taro Kanayama

Masahiro Kagawa

Kingo Sawada

Tsutomu Ide

Yoshinori Sugie

Fumio Murase

Kazuo Omura

Ryoji Kusakabe

Masaharu Kita

Ken Shimamoto

Sho Inui

Toshio Onishi

Yoshnori Sugie

Masao Shoji

Susumu Itadani

Yuuji Hashimoto

Susumu Itatani

Takayasu Takubo

Kiyoshi Uwai

Yasuhiro Omori

Noritsugu Itakura

Tohru Hayashi

Kohei Yoshino

Hisashi Harada

Akio Ejima

Hisato Nishisaka

Kenji Ichino

Yoshitomi Onoda

Takanori Tamari

Nobutaka Kurosawa

Yasue Koyama

Motoaki Itatani

Hiroyuki Matsui

Eiichi Yokoyama

Makoto Kitazawa

Yasuo Nishida

Mikio Kodaka

Kohji Yuda

Yasuhiro Ohmori

A method is directed to a production of a bearing device for a wheel including an inner member and an outer member rotatable relative to each other through a plurality of rolling elements, in which a component part forming one of the inner member and the outer member is a hot forged product. In the practice of this method, during or at the end of a hot forging step for hot forging the component part, a portion of the component part is cooled by spraying a coolant or by controlling an atmospheric temperature, to thereby render a matrix of the component part to represent a standard structure and render a surface portion of the component part to represent a non-standard structure.

Process for producing bearing device for wheel

A steel part having a long rolling contact fatigue life and capable of further increasing the life of a bearing under severer using condition than usual conditions. The steel part includes steel having a composition containing 0.7% by mass to 1.1% by mass of C, 0.5% by mass to 2.0% by mass of Si, 0.4% by mass to 2.5% by mass of Mn, 1.6% by mass to 5.0% by mass of Cr, 0.1% by mass to less than 0.5% by mass of Mo, 0.010% by mass to 0.050% by mass of Al, less than 0.0015% by mass of Sb as an impurity, and the balance composed of Fe and inevitable impurities, the steel being hardened and tempered. In the steel structure of a portion from the surface to a depth of 5 mm, residual cementite has a grain diameter of 0.05 to 1.5 &#x3bc;m, prior austenite has a grain diameter of 30 &#x3bc;m or less, and the ratio by volume of the residual austenite is less than 25%.

Method for producing steel part having long rolling contact fatigue life

A steel composition contains: 0.05% or less of C; 0.5% or less of Si; 0.20% to 1.80% of Mn; 0.03% or less of P; 0.005% or less of S; 14.0% to 18.0% of Cr; 5.0% to 8.0% of Ni; 1.5% to 3.5% of Mo; 0.5% to 3.5% of Cu; 0.05% or less of Al; 0.20% or less of V; 0.01% to 0.15% of N; and 0.006% or less of O on a mass basis, and satisfies the following expressions: Cr+0.65Ni+0.6Mo+0.55Cu&#x2212;20C&#x2267;18.5 and Cr+Mo+0.3Si&#x2212;43.5C&#x2212;0.4Mn&#x2212;Ni&#x2212;0.3Cu&#x2212;9N&#x2266;11 (where Cr, Ni, Mo, Cu, C, Si, Mn, and N represent their respective contents (mass %)). After such a steel pipe material is formed into a steel pipe, the steel pipe is quenched by cooling after heating to a temperature of the Atransformation point or more and tempered at a temperature of the Atransformation point or less.

Stainless-steel pipe for oil well and process for producing the same

A hot forging facility enabling the manufacture of a hot forged product excellent in fatigue properties and cold workability is provided. A heating furnace for heating a steel material and a hot forging apparatus for performing forging of the heated steel material are sequentially arranged on a transport line. A partially cooling apparatus/apparatuses for partially cooling a forged product after hot forging is provided on an exit side of the hot forging apparatus.

Hot forging facility

A hot forged product including hardened areas introduced by partial cooling after hot forging, and unhardened areas, wherein Vickers hardness Vof the hardened areas on the surface and Vickers hardness Vof the unhardened areas satisfy the following formula (1): (V&#x2212;V)/V: 0.1 to 0.8.

Hot forged product with excellent fatigue strength, method for making the same, and machine structural part made from the same

We provide a steel product that includes, by mass %, C: 0.35-0.7%, Si: 0.30-1.1%, Mn: 0.2-2.0%, Al: 0.005-0.25%, Ti: 0.005-0.1%, Mo: 0.05-0.6%, B: 0.0003-0.006%, S: 0.06% or less, P: 0.02% or less, Cr: 0.2% or less, and the balance Fe and inevitable impurities, and has a structure of bainite and/or martensite, the total volume fraction of bainite and martensite being 10% or more, and an induction hardened member that is made of the steel product having a hardened surface layer formed by induction hardening and has a prior austenite grain size of 12 &#x3bc;m or less through the layer thickness. The member has high fatigue strength and therefore is suitable for an automobile drive shaft, an automobile constant velocity joint or the like.

Steel product for induction hardening, induction-hardened member using the same, and methods producing them

A steel pipe is produced by a method including performing diameter-reducing rolling on a steel pipe in a temperature range of from 600&#xb0; C. to Acwith a reduction in diameter of not less than 30%, preferably after heating the steel pipe to temperatures of not lower than Acthe steel pipe being produced by seam-welding strip steel, or a method further including the step of performing heat treatment of holding the rolled steel pipe in a temperature range of from 600&#xb0; C. to 900&#xb0; C. for a time of 1 second or longer during cooling subsequent to the diameter-reducing rolling or by reheating the rolled steel pipe after the cooling.

High-workability steel pipe and method of producing same

A steel tube having a composition which contains: 0.05 to 0.30% of C; 1.8 to 4.0% of Mn; Si; and Al is subjected to a diameter-reducing rolling process in which the total diameter-reduction rate is no less than 20% and the temperature at which the diameter-reducing rolling process is finished is no higher than 800&#xb0; C., whereby a structure constituted of martensite and/or bainite or further of ferrite is obtained as a transformation product from the deformed &#x3b3;. As a result, a steel tube having tensile strength of 1000 MPa or more and excellent three-point-bending property can be obtained. The composition of the steel tube of the present invention may further include at least one type of element selected from the group consisting of Cu, Ni, Cr and Mo, or at least one type of element selected from the group consisting of Nb, V, Ti and B, or at least of one type selected from the group consisting of REM and Ca.

Steel pipe for use in reinforcement of automobile and method for production thereof

An impeder, for manufacturing a welded pipe, including an insulating casecontaining laminationshaving coated steel sheetsformed by providing an insulating coating on untreated steel sheets having a thickness of 0.3 mm or less and an insulating casecontaining the laminations, wherein the steel sheets contain 1.5-20% of Cr, 2.5-10% of Si, and 100 ppm or less of C and N in total, or further contain one or more of Al, Mn, and P, where the content of Al is 5% or less and the content of each of Mn and P is 1% or less, the remainder being Fe and unavoidable impurities; and preferably have a resistivity of 60 &#x3bc;&#x3a9;&#xb7;cm or more.

Impeder for manufacturing welded pipe

A method of producing a high-strength high-toughness martensitic stainless steel seamless pipe which includes heating a martensitic stainless steel raw material to an austenitic range and subjecting the raw material to piercing and elongating to form an original pipe. The original pipe is cooled to form a structure substantially composed of martensite in the original pipe. The original pipe is reheated to a temperature in the dual-phase range between the Atransformation point and the Atransformation point, and is subjected to finishing rolling at an initial rolling temperature T (&#xb0; C.) between the Atransformation point and the Atransformation point. The original pipe is then cooled to form a processed pipe. The processed pipe is tempered at a temperature below the Atransformation point. The reduction in area R in the finishing rolling step may be in the range of 10% to 90%, and the initial rolling temperature T and the reduction in area R may satisfy the relationship 800&#x2266;T&#x2212;0.625R&#x2266;850.

Method for making high-strength high-toughness martensitic stainless steel seamless pipe

A stainless steel tube having excellent formability for secondary operation comprises: a chemical composition including not more than 0.20 mass % of C; not more than 1.5 mass % of Si; not more than 2.0 mass % of Mn; 10-18 mass % of Cr; not more than 0.03 mass % of N; or further at least one type of element selected from the group of: not more than 0.6 mass % of Cu; not more than 0.6 mass % of Ni; not more than 2.5 mass % of Mo; not more than 1.0 mass % of Nb; not more than 1.0 mass % of Ti; and not more than 1.0 mass % of V; Fe as the remainder and the inevitable impurities; and a structure constituted of ferrite or ferrite and martensite, wherein the TE value defined by the following formula exceeds 25,000 Mpa&middot;%, TE&equals;TS&times;(El&plus;21.9) TS represents the tensile strength in the tube axial direction, and El represents the elongation in such direction.

Stainless steel tube for automobile structure

A welded steel pipe is formed by heating or soaking an untreated welded steel pipe having a steel composition containing, on the basis of mass percent: about 0.03% to about 0.2% C, about 2.0% or less of Si, not less than about 1.0% to about 1.5% Mn, about 0.1% or less of P, about 0.01% or less of S, about 1.0% or less of Cr, about 0.1% or less of Al, about 0.1% or less of Nb, about 0.1% or less of Ti, about 0.1% or less of V, and about 0.01% or less of N; and by reduction-rolling the treated steel pipe at a cumulative reduction rate of at least about 35% and a final rolling temperature of about 500&deg; C. to about 900&deg; C. The welded steel pipe exhibits excellent hydroformability, i.e., has a tensile strength of at least about 590 MPa and an n&times;r product of at least about 0.22. The treated steel pipe is preferably reduction-rolled at a cumulative reduction rate of at least about 20% below the Ar transformation point.

Welded steel pipe having excellent hydroformability and method for making the same

The invention provides a high-carbon steel pipe having superior cold workability and induction hardenability, and a method of producing the steel pipe. The method comprises the steps of heating or soaking a base steel pipe having a composition containing C: 0.3 to 0.8%, Si: not more than 2%, and Mn: not more than 3%, and then carrying out reducing rolling on the base steel pipe at least in the temperature range of (Ac , transformation point &minus;50&deg; C.) to Ac , transformation point with an accumulated reduction in diameter of not less than 30%. A structure in which the grain size of cementite is not greater than 1.0 &mgr;m is obtained, thus resulting in improved cold workability and induction hardenability.

High carbon steel pipe excellent in cold formability and high frequency hardenability and method for producing the same

A welded steel pipe is formed by heating or soaking an untreated welded steel pipe having a steel composition containing, on the basis of mass percent: about 0.05% to about 0.2% C; about 0.2% or less of Si; about 1.5% or less of Mn; about 0.1% or less of P; about 0.01% or less of S; about 0.1% or less of Al; and about 0.01% or less of N; and by reduction-rolling the treated steel pipe at a cumulative reduction rate of at least about 35% and a final rolling temperature of about 500&deg; C. to about 900&deg; C. The welded steel pipe exhibits excellent hydroformability, i.e., has a tensile strength of at least about 400 MPa and an n&times;r product of at least about 0.22. The treated steel pipe is preferably reduction-rolled at a cumulative reduction rate of at least about 20% below the Ar transformation point. The welded steel pipe is suitable for forming structural components.

A welded steel pipe is formed by heating or soaking an untreated welded steel pipe having a steel composition comprising, on the basis of mass percent: about 0.05% to about 0.3% C; about 2.0% or less of Si; more than about 1.5% to about 5.0% Mn; about 0.1% or less of P; about 0.01% or less of S; about 0.1% or less of Cr; about 0.1% or less of Al; about 0.1% or less of Nb; about 0.3% or less of Ti; and about 0.01% or less of N; and by diameter-reduction-rolling the treated steel pipe at a accumulated diameter reduction rate of at least about 35% and a finish rolling temperature of about 500&deg; C. to about 900&deg; C. The welded steel pipe exhibits excellent hydroformability, i.e., has a tensile strength of about 780 MPa or more and a n&times;r product of at least about 0.15. The treated steel pipe is preferably diameter-reduction-rolled at a accumulated diameter reduction rate of at least about 20% below the Ar transformation point.

Growing community of inventors

Tokyo, Japan

Takaaki Toyooka