Nippon Steel Corporation

Nippon Steel Sumitomo Metal Corporation

Fukuju Industry Corporation Ltd

Yasuhiro Shinohara

Koji Hashimoto

Akira Hashimoto

Nobuhiro Fujita

Manabu Takahashi

Naoki Yoshinaga

Shinya Sakamoto

Takuya Hara

Kaoru Kawasaki

Hitoshi Asahi

Takehide Senuma

Yasushi Hasegawa

Eiji Tsuru

Kensuke Nagai

Yukinobu Nagata

Tohru Yoshida

Natsuko Sugiura

Hideyuki Nakamura

Yuichi Sato

Hideki Hamatani

Yoshio Terada

Takaaki Fukushi

Yutaka Takagi

Masakazu Ozaki

Taishi Fujishiro

Eiichi Yamashita

Naoki Doi

Yutaka Hattori

Izuru Minato

Nozomu Abe

Kiyoshi Ebihara

Kazuteru Tsutsui

Naoshi Ayukawa

Teruhisa Takamoto

Kazuhiro Inoue

Bunshi Kato

Junichi Okamoto

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

A pipeline is a pipeline having plural weld zones in which ends of plural steel pipes are joined by welding, the plural steel pipes are produced from plural charges of molten steel having one or more steel compositions; yield point elongation is not present on a stress-strain curve obtained when stress is applied in a longitudinal direction of each of the steel pipes; a thickness of each of the steel pipes t (mm) and an average pipe outside-diameter D (mm) satisfy t/D&#xd7;100&#x2264;6; and in the plurality of the weld zones, &#x394;YS which is a yield strength difference between one steel pipe and the other steel pipe that are welded to each other (MPa), and YR representing a yield ratio that is a ratio of the yield strength to tensile strength of a pipe having a low yield strength out of the one steel pipe and the other steel pipe, satisfy &#x394;YS&#x2264;&#x2212;1.75&#xd7;YR+230.

Pipeline and manufacturing method thereof

A pipeline is a pipeline having plural weld zones in which ends of plural steel pipes are joined by welding, the plural steel pipes are produced from plural charges of molten steel having one or more steel compositions; yield point elongation is not present on a stress-strain curve obtained when stress is applied in a longitudinal direction of each of the steel pipes; a thickness of each of the steel pipes t (mm) and an average pipe outside-diameter D (mm) satisfy t/D&#xd7;100&#x2266;6; and in the plurality of the weld zones, &#x394;YS which is a yield strength difference between one steel pipe and the other steel pipe that are welded to each other (MPa), and YR representing a yield ratio that is a ratio of the yield strength to tensile strength of a pipe having a low yield strength out of the one steel pipe and the other steel pipe, satisfy &#x394;YS&#x2266;&#x2212;1.75&#xd7;YR+230.

An electric resistance welded steel pipe which has sufficient strength and low-temperature toughness and a low yield ratio and which is suitable as a line pipe to be laid in depths of the sea, characterized in that: the composition of the base material contains, in mass %, 0.05 to 0.10% of C, 1.00 to 1.60% of Mn, and 0.005 to less than 0.035% of Nb, and has a Ceq value of 0.23 to 0.38; and the metal microstructure of the base material contains 3 to 13% of martensite in area fraction with the balance being ferrite.

Electric resistance welded steel pipe

A liquid phase diffusion bonded pipe joint comprised of metal pipes or a metal pipe and a joint pipe joined by liquid phase diffusion bonding, the liquid phase diffusion bonded pipe joint comprised of a metal joint provided with a tapered slanted part press-fit into an end of a metal pipe by a thrust in a pipe axial direction while expanding the metal pipe in inside diameter and tightly engaging with the end and a joining surface part continuing from the tapered slanted part and joined with an end face of the metal pipe by liquid phase diffusion bonding and a metal pipe tightly engaging with the tapered slanted part in the expanded state and with an end face joined with the joining surface part by liquid phase diffusion bonding.

Liquid phase diffusion bonded pipe joint

The present invention provides a thick welded steel pipe excellent in low temperature toughness in which contents of Mn and Mo satisfy (Expression 1) below, Pcm obtained by (Expression 2) below is 0.16 to 0.19, and a metal structure of a base material steel plate consists of ferrite being 30 to 95% in an area ratio and a low temperature transformation structure, and in a metal structure of a coarse-grained HAZ, an area ratio of grain boundary ferrite is 1.5% or more, the total area ratio of the grain boundary ferrite and intragranular ferrite is not less than 11% nor more than 90%, an area ratio of MA is 10% or less, and its balance is composed of bainite.1.2325&#x2266;(0.85&#xd7;[Mn]&#x2212;[Mo])&#x2266;1.5215&#x2003;&#x2003;(Expression 1)andPcm=[C]+[Si]/30+([Mn]+[Cu]+[Cr])/20+[Ni]/60+[Mo]/15+[V]/10&#x2003;&#x2003;(Expression 2).

Thick welded steel pipe excellent in low temperature toughness, manufacturing method of thick welded steel pipe excellent in low temperature toughness, and steel plate for manufacturing thick welded steel pipe

The present invention provides high strength steel plate and high strength welded pipe excellent in ductile fracture characteristic and methods of production of the same, that is, high strength steel plate excellent in ductile fracture characteristic, and high strength welded pipe using that steel plate as a base material, having a tensile strength corresponding to the X100 class of the API standard, containing, by mass %, C: 0.01 to 0.5%, Si: 0.01 to 3%, Mn: 0.1 to 5%, P: 0.03% or less, and S: 0.03% or less and a balance of Fe and unavoidable impurities, having a microstructure comprised of, by area ratio, 1 to 60% of ferrite and the balance of bainite and martensite, having a maximum value of the {100} accumulation degree of the cross-section rotated 20 to 50&#xb0; from the plate thickness cross-section about the rolling direction as an axis of 3 or less, and having plate thickness parallel cracks measured by ultrasonic flaw detection of less than 1 mm.

High strength steel plate and high strength welded pipe excellent in ductile fracture characteristic and methods of production of same

This high-strength steel pipe includes, by mass %, C: 0.02% to 0.09%, Mn: 0.4% to 2.5%, Cr: 0.1% to 1.0%, Ti: 0.005% to 0.03%, Nb: 0.005% to 0.3%, and a balance consisting of Fe and inevitable impurities, in which Si, Al, P, S, and N are limited to 0.6% or less, 0.1% or less, 0.02% or less, 0.005% or less, 0.008% or less, respectively, the bainite transformation index BT is 650&#xb0; C. or less, and the microstructure thereof is a single bainite microstructure including first bainite and second bainite, the first bainite being a gathered microstructure of bainitic ferrite including no carbide, and the second bainite being a mixed microstructure of bainitic ferrite including no carbide and cementite between the bainitic ferrites.

High-strength steel pipe and producing method thereof

The present invention provides a line pipe of, e.g., the API standard X60 to X100 class. The line pipe has an excellent deformability, as well as excellent low temperature toughness and high productivity, a steel plate used as the material of the steel pipe. Methods for producing the steel pipe and the steel plate are also provided. In particular, a high-strength steel plate excellent in the deformability has a ferrite phase is dispersed finely, and accounts for 5% to 40% in area percentage in a low temperature transformation structure mainly composed of a bainite phase. For example, most grain sizes of the ferrite phase are smaller than the average grain size of the bainite phase. A high-strength steel pipe excellent in deformability is also provided, in which a large diameter steel pipe is produced through forming the steel plate into a pipe shape. The steel pipe has the above-referenced structure, and satisfies the conditions that YS/TS is 0.95 or less and YS&#xd7;uEL is 5,000 or more. Methods for producing such steel plate and steel pipe are also provided.

High-strength steel sheet and high-strength steel pipe excellent in deformability and method for producing the same

The present invention provides a steel sheet excellent in workability, which may be used for components of an automobile or the like, and a method for producing the same. More specifically, according to one exemplary embodiment of the present invention, a steel sheet excellent in workability, including in mass, 0.08 to 0.25% C, 0.001 to 1.5% Si, 0.01 to 2.0% Mn, 0.001 to 0.06% P, at most 0.05% S, 0.001 to 0.007% N, 0.008 to 0.2% Al, at least 0.01% Fe. The steel sheet having an average r-value of at least 1.2, an r-value in the rolling direction of at least 1.3, an r-value in the direction of 45 degrees to the rolling direction of at least 0.9, and an r-value in the direction of a right angle to the rolling direction of at least 1.2.

Steel sheet excellent in workability

Cold-rolled steel sheet excellent in workability

Method to produce steel sheet excellent in workability

Steel plate exhibiting excellent workability and method for producing the same

A precision machine part is made of a plurality of pieces with a transient liquid phase diffusion bonding alloy provided between the pieces to bond them together. The precision machine part has one or more conveyance passages formed in it, has a longitudinal axis and is configured to permit passage of liquid or gas through the conveyance passage from a pipe line or cylinder. The pieces of the precision machine part are adhered to each other by transient liquid phase bonding with a ribbon of an amorphous bonding alloy. The bonding alloy can contain 1 to 10 atomic % V or can contain 1 to 15 atomic % of B or P or a mixture of B and P and 1 to 10 atomic % V, the balance being Fe and unavoidable impurities, and can exhibit an amount of contraction in a bonding stress loading direction caused by plastic deformation in the bonding process of not more than 5%. The bonding alloy may be an amorphous Ni-based alloy.

Liquid phase diffusion welded metal-made precision machine component and production method thereof

The present invention is a high strength steel pipe excellent in formability in hydroforming and similar forming methods, characterized by: containing, in mass, C of 0.0005 to 0.30%, Si of 0.001 to 2.0%, Mn of 0.01 to 3.0% and appropriate amounts of other elements if necessary, with the balance consisting of Fe and unavoidable impurities; and an average for the ratios of the X-ray strength in the orientation component group of {110}&#x3c;110&#x3e; to {111}&#x3c;110&#x3e; to random X-ray diffraction strength on a plane at the wall thickness center being 2.0 or more and/or a ratio of the X-ray strength in the orientation component of {110}&#x3c;110&#x3e; to random X-ray diffraction strength on the plane at the wall thickness center being 3.0 or more.

Steel pipe excellent in formability and method of producing the same

Growing community of inventors

Futtsu, Japan

Yasuhiro Shinohara