Jfe Steel Corporation

Kawasaki Steel Corporation

Toyota Jidosha Kabushiki Kaisha

Jtekt Corporation

Jfe Welded Pipe Manufacturing Co., Ltd.

Yoshikazu Kawabata

Masatoshi Aratani

Takaaki Toyooka

Takatoshi Okabe

Akira Yorifuji

Kei Sakata

Yuji Hashimoto

Motoaki Itadani

Makio Gunji

Mitsuo Kimura

Takuya Nagahama

Masanori Nishimori

Kunio Fukuda

Kaneharu Okuda

Takashi Obara

Akio Sato

Shunsuke Toyoda

Ryoji Matsui

Masayuki Sakaguchi

Atsushi Ogino

Yasue Koyama

Susumu Sato

Susumu Satoh

Koji Suzuki

Yasuhide Ishiguro

Mitsuyuki Fujisawa

Saiji Matsuoka

Takeo Yamamoto

Masahiko Morita

Takaaki Hira

Kazuhide Ishii

Fusao Togashi

Kinya Nakagawa

Osamu Sonobe

Kenichi Iwazaki

Tomohiko Sato

Shinsaku Kokubo

Norimasa Hirata

Hiromichi Hori

Tetsuro Sawaki

Makoto Kitazawa

Kaname Onoda

Masayoshi Ishida

Manabu Nishino

An electric resistance welded steel pipe or tube comprises: a base metal being a steel sheet having a specific chemical composition and an electric resistance weld portion having a bond width of 40×10m or more and 120×10m or less, wherein C-Cis 0.05 mass % or less, where C-Cis a difference between Cin mass % which is a minimum C content of the electric resistance weld portion and Co in mass % which is a C content of the steel sheet, and a depth of a total decarburized layer in each of an inner surface layer and an outer surface layer of the electric resistance welded steel pipe or tube is 50×10m or less.

Electric resistance welded steel pipe or tube

Provided is an electric resistance welded steel pipe or tube having excellent fatigue durability after rapid and short-time heating quenching treatment. An electric resistance welded steel pipe or tube comprises: a base metal being a steel sheet having a specific chemical composition and an electric resistance weld portion having a bond width of 40&#xd7;10m or more and 120&#xd7;10m or less, wherein C-Cis 0.05 mass % or less, where C-Cis a difference between Cin mass % which is a minimum C content of the electric resistance weld portion and Cin mass % which is a C content of the steel sheet, and a depth of a total decarburized layer in each of an inner surface layer and an outer surface layer of the electric resistance welded steel pipe or tube is 50&#xd7;10m or less.

Electric resistance welded steel pipe or tube and production method for electric resistance welded steel pipe or tube

A method for manufacturing an electric resistance welded steel tube for high-strength thin hollow stabilizers is provided. A steel with a certain chemical composition is heated to a temperature of 1000 to 1300&#xb0; C., hot rolled under conditions where the rolling finish temperature is 750 to 950&#xb0; C., cooled, coiled into a coil at 500 to 650&#xb0; C., and skin pass rolled with a rolling reduction ratio of not less than 0.3%. The resultant hot rolled sheet is electric resistance welded into an electric resistance welded steel tube, which is then reheated to a temperature of 800 to 1100&#xb0; C. and hot stretch-reducing rolled under conditions where the rolling finish temperature is not more than 850&#xb0; C. and the cumulative diameter reduction is not more than 75%. Consequently, a thin electric resistance welded steel tube is produced.

Electric resistance welded steel tubes for high-strength thin hollow stabilizers, and methods for manufacturing the same

A seamless steel tube has a particular composition and a structure with an average prior &#x3b3; grain size of 150 &#x3bc;m or less in an axial cross-section after cold drawing and heat treatment. The structure retards the growth of a fatigue crack. The steel tube has a tensile strength TS of 500 MPa or more and good internal pressure fatigue resistance and is suitable for use as a fuel injection tube under high injection pressures. The composition of the steel tube may further contain at least one of Cu, Ni, Cr, Mo, and B; at least one of Ti, Nb, and V; and/or Ca.

Seamless steel tube for fuel injection

Disclosed is a high-strength welded steel pipe for airbag inflators that has high toughness and workability. A base material portion of the steel pipe has a composition containing, in mass %, C: 0.02 to 0.08%, Si: 0.001 to 1.0%, Mn: 0.1 to 2.0%, P: 0.1% or less, Al: 0.01 to 0.1%, N: 0.01% or less, Ti: 0.01 to 0.20%, and V: 0.01 to 0.50%, with the balance being Fe and incidental impurities. The base material portion has a structure that includes a ferrite phase having an average grain size of 10 &#x3bc;m or less at an area fraction of 90% or more and a Ti, V-based carbide having an average grain size of 10 nm or less and dispersed in the ferrite phase. The welded steel pipe has a high tensile strength TS of 780 MPa or more and a strength-elongation balance TS&#xd7;El of 15,000 MPa % or more. The difference &#x394;HV in Vickers hardness between the base material portion and the welded portion is 60 points or less. In a softened portion having Vickers hardness different from the Vickers hardness of the base material portion by at least 30 points, a softened width Ws in a circumferential direction is 0.05 mm or less.

High-strength welded steel pipe for airbag inflator and method for manufacturing the same

A method for manufacturing an electric resistance welded steel tube including: forming a steel tube material into an almost cylindrical open pipe, the steel tube material being a steel sheet wherein Ti and N satisfy (N/14)&#x3c;(Ti/47.9); forming an electric resistance welded steel tube by bonding ends of the open pipe to each other by induction resistance welding with heat input controlled so that the bond width is 30 to 65 &#x3bc;m; heating the electric resistance welded steel tube to a temperature equal to or higher than the Actransformation temperature; and diameter-reducing rolling the heated electric resistance welded steel tube with rolling reduction expressed by an outer diameter ratio greater than (1&#x2212;25/the bond width before diameter-reducing rolling (&#x3bc;m))&#xd7;100% such that the bond width is 25 &#x3bc;m or less.

Method for electric resistance welded steel tube

A method enhances fatigue strength of ear portions which are high fatigue risk parts in a torsion beam almost without bringing about disadvantages in terms of productivity and cost. A torsion beam is formed with a portion of the tubular body into an approximately U-shape in cross section by crushing the portion of the tubular body in the radial direction and, thereafter, due to bending with a bottom line set as a belly side of bending, a bending strain of 2 to 6% in the tube longitudinal direction on a tensile side is imparted to the ear portions.

Torsion beam manufacturing method and torsion beam

A frictionally press-bonded member includes a steel pipe, and a stab. The steel pipe has opposite ends. The stab is frictionally press-bonded to at least one of the opposite ends of the steel pipe. The steel pipe is subjected to a normalizing treatment before being frictionally press-bonded to the stab.

Frictionally press-bonded member

A steel pipe blank having a composition containing 0.5% or less C and 85% or more Fe in terms of mass percent is heated, and stretch-reducing is then performed so that the diameter decrease ratio is 15% or more and the rolling finishing temperature is (the Artransformation point&#x2212;10)&#xb0; C. or lower. Consequently, a structure in which the ratio of X-ray diffraction intensity obtained from the plane in which the &#x3c;100&#x3e; direction of crystal grains is preferentially oriented parallel to the circumference direction and the &#x3c;011&#x3e; direction of crystal grains is preferentially oriented parallel to the rolling direction of the steel pipe to that obtained for a three-dimensionally randomly oriented sample is 3.0 or more is formed, and the r-value is increased, thereby improving the magnetic properties of the steel pipe.

Steel pipe with good magnetic properties and method of producing the same

A high-tensile strength welded steel tube has excellent formability and torsional fatigue endurance after being formed into cross-sectional shape and then stress-relief annealed. A steel material used has a composition which contains C, Si, Al, 1.01% to 1.99% Mn, 0.041% to 0.150% Ti, 0.017% to 0.150% Nb, P, S, N, and O such that the sum of the content of Ti and that of Nb is 0.08% or more, the content of each of C, Si, and Al being within an appropriate range, the content of each of P, S, N, and O being adjusted to a predetermined value or less.

High-tensile strength welded steel tube for structural parts of automobiles and method of producing the same

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

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

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Tokyo, Japan

Yoshikazu Kawabata