Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Hideki Hamatani

Fuminori Watanabe

Takaaki Fukushi

Hiroyuki Kawata

Kazuto Yamamoto

Noriyuki Suzuki

Naoki Maruyama

Masafumi Azuma

Yasunobu Miyazaki

Seiji Furusako

Koichi Sato

Kenichi Yamamoto

Yoshihiro Hashimoto

Yusuke Takeda

Noboru Hasegawa

Nobuo Mizuhashi

Hatsuhiko Oikawa

Shinji Kodama

Takao Miura

Takashi Miyakawa

Michimasa Mukai

Masakazu Ozaki

Michitoshi Tanimoto

Sunao Takeuchi

Yoshifumi Karube

Hitoshi Asahi

Masafumi Miyazaki

Tohru Okada

Satoshi Kato

Yasuhiro Shinohara

Chisato Wakabayashi

Kotaro Watanabe

Yoshiaki Hirota

Takashi Oosawa

Tetsuro Nose

Tomohito Tanaka

Keinosuke Iguchi

Manabu Mizumoto

Kenichi Asai

Toshisuke Fukami

Yuusuke Ichinose

Kunihiko Hatabara

Oleg Pavlovich Solonenko

Andrey Vladimirovich Smirnov

Kimiharu Tanaka

Tomohiro Nakaji

Takuya Asano

Masahide Hayashi

Manabu Ueda

Masaki Ina

Yuya Tomonaga

Kazumoto Tsukakoshi

Takashi Motoyoshi

An electric resistance welded steel pipe for a torsion beam, in which a base metal portion includes, in terms of % by mass, 0.04 to 0.12% of C, 0.03 to 1.20% of Si, 0.30 to 2.50% of Mn, 0.08 to 0.24% of Ti, 0.005 to 0.500% of Al, 0.01 to 0.06% of Nb, and 0.0005 to 0.0100% of N, a balance including Fe and impurities, wherein V, defined by the following Formulae (i) and (ii), is 200 or more, a mass ratio of Ti content to C content is from 0.85 to 5.00, an areal ratio of ferrite is 80% or more, an average crystal grain size of ferrite crystal grains is 10 &#x3bc;m or less, and an average aspect ratio of ferrite crystal grains is 2.0 or less, in a metallographic microstructure of a central portion in a wall thickness direction of the base metal portion;log=2.94&#x2212;0.75(&#x3b2;&#x2212;1)&#x2003;&#x2003;Formula (i);&#x3b2;=2.70.40.450.8&#x2003;&#x2003;Formula (ii).

Electric resistance welded steel pipe for torsion beam

By obtaining a spot-welded joint being a spot-welded joint formed by overlapping a plurality of pieces of steel plates (A,B) and performing spot welding on the steel plates, including a high-strength steel plate whose tensile strength is 750 (MPa) to 2500 (MPa), being at least one piece of steel plate out of the plurality of pieces of steel plates, in which a carbon equivalent Ceq of the high-strength steel plate is 0.20 mass % to 0.55 mass %, and ten or more of iron-based carbides in each of which a length of a longest portion is 0.1 (&#x3bc;m) or more exist in a square regionwithin a heat-affected zoneof a cross section that passes through a center of a welding mark, and is cut along a plate thickness direction of the steel plates (A,B), a cross tensile strength of the spot-welded joint to be formed is improved.

Spot-welded joint and spot welding method

The present invention provides electric-resistance welded steel pipe optimal for applications such as production of shale gas which is comprised of steel having a chemical composition which contains, by mass %, respectively, C: 0.08 to 0.18%, Si: 0.01% to 0.50%, Mn: 1.30 to 2.1%, Al: 0.001 to 0.10%, Nb: 0.005 to 0.08%, and Ti: 0.005 to 0.03%, is limited to N 0.008% or less, P: 0.020% or less, and S: 0.010% or less, and has a balance of Fe and unavoidable impurities, wherein a structure at a center part of thickness is 40% to 70% by area of ferrite phase having a circle-equivalent diameter of 1.0 &#x3bc;m to 10.0 &#x3bc;m and a balance of a low temperature transformation phase comprising a bainite phase, and Ceq satisfies 0.32&#x2264;Ceq&#x2264;0.60.

Electric-resistance welded steel pipe

A welded state monitoring system according to an aspect of the present invention is a welded state monitoring system used for plasma shielded electric resistance welding in which electric resistance welding is performed while irradiating a weld zone of a steel sheet with plasma, and is provided with a plasma irradiation device which irradiates the weld zone with plasma, a first image capturing device which captures an image of the weld zone from above and has an image sensor capable of detecting light having a wavelength of 850 nm or more, a first wavelength region limiting device which limits light incident on the first image capturing device to a wavelength region of 850 nm or more, and an image processing device which subjects the image captured by the first image capturing device to image processing and analyzes the welded state of the weld zone thereby being able to analyze the welded state without being affected by the plasma.

Welded state monitoring system and welded state monitoring method

An electric resistance welded steel pipe for an oil well includes in terms of mass %: 0.02 to 0.14% of C, 0.05 to 0.50% of Si, 1.0 to 2.1% of Mn, 0.020% or less of P, 0.010% or less of S, 0.010 to 0.100% of Nb, 0.010 to 0.050% of Ti, 0.010 to 0.100% of Al, and 0.0100% or less of N. Contents of Cu, Ni, Cr, Mo, V, and B are 0 to 0.50%, 0 to 1.00%, 0 to 0.50%, 0 to 0.30%, 0 to 0.10%, and 0 to 0.0030%, respectively. Remainder consisting of Fe and unavoidable impurities. In a case that a full thickness specimen is subjected to a pipe axis direction tensile test, a tensile strength is 780 MPa or more, 0.2% proof stress/tensile strength is 0.80 or more, and 2% flow stress/tensile strength is from 0.85 to 0.98.

Electric resistance welded steel pipe for oil well

Electric resistance welded steel pipe excellent in weld zone quality suitable for oil country tubular goods and line pipe wherein steel plate forming the base metal of the electric resistance welded steel pipe has a predetermined chemical composition, the contents of Ca, O, S, Ce, La, and Al satisfy the oxide-based inclusions in the weld zone of the electric resistance welded steel pipe contains one or both of Ce and La, and the long axis/short axis of the oxide-based inclusions is 2.5 or less.

Electric resistance welded steel pipe excellent in weld zone and method of production of same

In a spot welded joint according to an aspect of the present invention, with respect to a rectangular planar region of 100 &#x3bc;m&#xd7;100 &#x3bc;m which is perpendicular to a sheet surface of the plurality of the steel sheets and which centers around an inner point spaced away by 100 &#x3bc;m in a direction parallel with the sheet surface from an edge of a nugget, in a case of measuring a P concentration at a pitch of 1 &#x3bc;m to obtain measured values of the P concentration at 100&#xd7;100 of measurement points, and in a case of repetitively calculating an average value of the measured values of the P concentration at 20 of the measurement points which are adjacent to each other and which are arranged in a row in the direction parallel with the sheet surface among the 100&#xd7;100 of the measurement points while shifting each one point to obtain 81&#xd7;100 of the average values, the number of the average values which are more than two times an average P concentration is 0 to 100.

Spot welded joint

A quenched steel pipe member is formed of a GI galvanized steel pipe, in a middle section in a longitudinal direction of the GI galvanized steel pipe, a cross-section perpendicular to the longitudinal direction has a substantially V shape including a contact section at which opposite parts of an inner circumferential surface of the GI galvanized steel pipe come into contact with each other, the contact section is bonded using a Fe&#x2014;Zn alloy phase, and a micro Vickers hardness at a location 50 &#x3bc;m deep from a base material surface layer is 95% or more of a micro Vickers hardness at a location 200 &#x3bc;m deep from the base material surface layer.

Quenched steel pipe member, vehicle axle beam using quenched steel pipe member, and method for manufacturing quenched steel pipe member

Provided is a spot welded joint () which includes at least one thin steel plate with a tensile strength of 750 MPa to 1850 MPa and a carbon equivalent Ceq of equal to or more than 0.22 mass % to 0.55 mass % and in which a nugget () is formed in an interface of the thin steel plates (A,B). In a nugget outer layer zone, a microstructure consists of a dendrite structure in which an average value of arm intervals is equal to or less than 12 &#x3bc;m, an average grain diameter of carbides contained in the microstructure is 5 nm to 100 nm, and a number density of carbides is equal to or more than 2&#xd7;10/mm.

Spot welded joint and spot welding method

An electric resistance welding operation management device manages a welding operation during manufacture of electric resistance welded steel pipe, in which heat is input to a steel plate, that is being conveyed along a specific conveyance direction and formed into a circular tube shape while pressing side faces of the metal plate with a pair of squeeze rolls, to weld together two circumferential direction edge portions of the metal plate converging in a V-shape. The electric resistance welding operation management device includes an image input section that inputs plural images and each including a Vee convergence region of the steel plate. The electric resistance welding operation management device includes a welding point position derivation section that derives the position of a welding point.

Electric resistance welding operation management device, electric resistance welding operation management method, and computer program

A plasma torch comprises a cascade between a cathode and an anode. The cascade is an inter-electrode insert. An interior of the cascade is shaped so that a diameter of the interior expands in series in a plurality of steps from a side of the cathode to a side of the anode. As a result of the cascade being provided, the output power of the plasma torch is obtained not by an increase in the electric current but by an increase in the arc electric voltage. Therefore, the lifespan of each of the electrodes, i.e., the cathode and the anode, becomes remarkably longer. In addition, since a quasi laminar flow of the plasma is generated in the interior of the cascade, a fluctuation in the output power of the plasma jet is reduced. Thus, it is possible to lower the driving and operating costs. Therefore, it is possible to perform surface treatment such as plasma spraying, utilizing a high-performance plasma processing, a processing of refractory powder materials, and plasma chemistry processing and the like, with a high degree of efficiency. In addition, a side shield module is provided at an outlet side of the anode of the forming nozzle. The side shield module generates a gas shield jet which is coaxial, annular, and low-velocity. Thus, gas from the surrounding environment is prevented from flowing in. Consequently, oxygen is prevented from entering the forming nozzle and the plasma jet. Hence, it is possible to generate a plasma jet having a low Reynolds number of the plasma forming gas, with a quasi laminar flow, exhibiting low noise, the diameter of its cross section expanding in a stable manner, having a long plasma length, and comprising argon, nitrogen, and hydrogen.

Plasma torch

An operation management device performs an operation management for electric resistance welding in which a strip-shaped metal plate is formed to have a cylindrical shape in such a manner that both end portions of the metal plate gradually face each other while the metal plate is conveyed, and a Vee convergence section, which is a portion at which both of the end portions butt against each other while facing each other, is welded. Furthermore, the operation management device includes: a measuring unit that measures a distance L [mm] between a first Vee convergence point at which both of the end portions of the metal plate geometrically come into contact with each other and a second Vee convergence point that is a contact point of both of the end portions of the metal plate, and a Vee convergence angle &#x3b8;[&#xb0;] at the first Vee convergence point on the basis of an image of an area including the Vee convergence section; and a determining unit that determines whether or not the distance L [mm] and the Vee convergence angle &#x3b8;[&#xb0;] satisfy the following equation (1).(&#x3b8;/&#x3b8;)&#x2266;35&#x2003;&#x2003;(1)

Operation management device, operation management method, and operation management program for high-frequency resistance welding and induction welding

The present invention provides a method of production of electric resistance welded steel pipe able to stably reduce weld defects due to oxides by firing plasma and furthermore able to reduce plasma jet noise and comprises shaping steel plateinto a tube and electric resistance welding the abutting end facesduring which blowing on at least the abutting end facesin the regionat the welding upstream side from the weld pointwhere the temperature becomes 650&#xb0; C. or more a reducing high temperature (pseudo) laminar plasma obtained by applying voltage to a reducing gas containing Hgas: 2 to 50 vol % to which is added a balance of Ar gas alone or a mixed gas of Ar gas to which Ngas, He gas, or both are added. At that time, it is preferable to make the applied voltage over 120V and the make the plasma blowing conditions satisfy the following formula (1). 

Method of production of electric resistance welded steel pipe and high Si or high Cr electric resistance welded steel pipe

The invention provides a system and method for monitoring the molten state of electric-resistance-welded pipe on-line. In the system, a mirror provided at a front end side inside a container receives light emitted by the welded parts of the tube-shaped steel strip through heat resistant glass from the side direction and reflects the image in the direction of a relay lens provided at a base end side of a relay lens unit. The relay lenses relay the image to a conversion lens, which forms the image on the imaging area of a CCD camera. Therefore, it is possible to capture the welded parts from the side direction by a resolution in accordance with the resolution of the CCD camera and possible to obtain information of the welded parts more accurately than in the past and on-line.

System and method for monitoring of welding state

Growing community of inventors

Tokyo, Japan

Hideki Hamatani