Kawasaki Steel Corporation

Jfe Steel Corporation

Kabushiki Kaisha Kobe Seiko Sho

Japan Marine United Corporation

Fumimaru Kawabata

Hiroki Ota

Takahiro Kubo

Keniti Amano

Tatsumi Kimura

Mitsuhiro Okatsu

Akio Ohmori

Noritsugu Itakura

Tohru Hayashi

Kazuhiko Shiotani

Takanori Okui

Tomoya Koseki

Kimihiro Nishimura

Kiyoshi Uchida

Kenji Oi

Masahiko Morita

Susumu Okada

Toshiyuki Hoshino

Hironori Miura

Naoya Hayakawa

Shigeki Nishiyama

Yoshiyuki Nakajima

Keito Ishizaki

Ryuji Muraoka

Hiroshi Shiomi

Makoto Ota

Tsunehisa Handa

Tadamasa Yamaguchi

Akio Kamada

Junya Matsuyama

Yasuyoshi Yamane

Yasushi Morikage

Shuichi Sakaguchi

Atsushi Shiga

Tatsufumi Uegaki

Shigeru Miyake

Yasuyashi Yamane

Hiroyuki Ookubo

Keizou Taoka

Kaoru Nagatani

A high-strength steel pipe has a tensile strength of 800 MPa or more and includes a weld metal having high cold-cracking resistance and high low-temperature toughness, wherein the weld metal contains C: 0.04% to 0.09% by mass, Si: 0.32% to 0.50% by mass, Mn: 1.4% to 2.0% by mass, Cu: less than 0.5% by mass, Ni: more than 0.9% by mass but not more than 4.2% by mass, Mo: 0.4% to 1.5% by mass, Cr: less than 0.5% by mass, V: less than 0.2% by mass, and the remainder of Fe and incidental impurities, and CS values calculated from the weld metal components using the equation CS=5.1+1.4[Mo]&#x2212;[Ni]&#x2212;[Mn]&#x2212;36.3[C] are equal to zero or more at both an internal surface and an external surface.

High-strength welded steel pipe including weld metal having high cold-cracking resistance and method for manufacturing the same

When manufacturing a straight steel section having a joint comprising a ball claw and a curved claw by hot-rolling a bloom vertically symmetrically to make a section blank having a flange A at a web end (first step), vertically asymmetrically hot-rolling the section blank to adjust the size of the web and form the flange into a rough joint B including a projection A (second step), and subjecting the projection to hot bend rolling into a curved claw (third step), wherein the bloom has a chemical composition comprising, in mass percentage, from 0.01 to 0.20% C, up to 0.8% Si, up to 1.8% Mn, up to 0.030% P, and up to 0.020% S; and therein the claw bending start temperature in the third step is a temperature of over Ar or up to Ar -50&deg; C., thereby achieving a depth of wrinkle flaws present on the inner surface side of the curved claw of up to 0.5 mm.

Linear shape steel excellent in joint fatigue characteristics and production method therefor

A steel material excellent in weathering resistance by defining the chemical ingredients in the steel each to a predetermined range and setting an ingredient parameter formula in accordance with the working circumstance thereby reducing the flow rust and, particularly, forming stable rust with good protective property even in a salty circumstance such as in coast districts is provided. Further, also considering the amount of A type inclusions and B type inclusions according to JIS G 0555, a steel material of excellent earthquake proofness and weathering proofness also including weld heat affect zone is provided.

Method of manufacturing corrosion resistant steel materials

A high-strength and high-toughness steel product having at least about 0.001% and less than about 0.030% by weight C, not more than about 0.60% by weight Si, from about 0.8 to 3.0% by weight Mn, from about 0.005 to 0.20% by weight Nb, from about 0.0003 to 0.0050% by weight B, and not more than about 0.005% by weight Al, wherein at least 90% of the product has a bainite structure. A method of making this steel product is subject to less stringent production controls because of the nature of the composition.

High-strength high-toughness steel products

The present invention relates to an H-shaped steel used as a building structure such as a column material or the like for highrise and super highrise building structures. In the bainite structure of extra-low-carbon steel, diffusive &agr; is finely dispersed in &agr; to ensure tensile strength at the 590-MPa level and significantly improve toughness in the direction of the flange thickness. Fine dispersion of &agr; is achieved by controlling Mn and Cu in proper ranges. In other word, the present invention provides 590MPa class heavy gauge H-shaped steel with excellent as-rolled toughness in the direction of the flange thickness, containing 0.001 to 0.025 wt % of C, 0.6 wt % or less of Si, 0.4 to 1.6 wt % of Mn, 0.025 wt % or less of P, 0.010 wt % or less of S, 0.1 wt % or less of Al, 0.6 to 2.0 wt % of Cu, 0.25 to 2.0 wt % of Ni, 0.001 to 0.050 wt % of Ti, and 0.0002 to 0.0030 wt % of B, wherein Mn/Cu&lE;2.0 and 250&lE;117 Mn (wt %)&plus;163 Cu (wt %)&lE;350 are satisfied.

590MPa class heavy gauge H-shaped steel having excellent toughness and method of producing the same

Rolled H-shapes having high strength and high toughness, and which can be produced using cheaper alloy components than conventional products and which can be manufactured with a high productivity, are disclosed. A method for manufacturing the H-shapes is also disclosed. The rolled H-shapes include 0.03 to 0.1 wt. % of Nb and 0.005 to 0.04 wt. % of Ti. The method includes a rough universal rolling process in which an accumulated reduction at a rolling temperature of 950&deg; C. or lower is 5% or larger, and reverse operation is conducted fast; and a finishing universal rolling, in which the rolling temperature is 750&deg; C. or higher. Preferably, in the rough universal rolling, the accumulated reduction at a rolling temperature of 950&deg; C. or lower is 50% or more.

Method of manufacturing high productive and high strength rolled H-shaped

Steel is obtained which comprises by wt %, C: 0.001-0.025%, Si: not more than 0.60%, Mn: 0.10-3.00%, P: 0.005-0.030%, S: not more than 0.01%, Al: not more than 0.10%, Cu: 0.1-1.5%, Ni: 0.1-6.0%, B: 0.0001-0.0050%, and the balance being Fe and inevitable impurities; since the steel contains C and P in small contents, stable amorphous rusts are formed on the surface thereof at an early stage; and steel simultaneously realizes excellent weather resistance, material weldability and toughness particularly in an environment such as a seashore district and the like where salt is present in a large amount.

Weatherable steel material

N&mdash;V(nitrogen-vanadium) containing continuous casting slab with no surface cracks suitable for the manufacture of non-tempered high tensile steel materials has a tensile strength of 490 MPa or more and excellent toughness. A method of manufacturing non-tempered high tensile steel materials uses the casting slab as the raw material. Compatibility between the desired properties of the materials utilizing VN and inhibition of the surface cracks of test pieces, can be attained by controlling the steel composition and the relationship between each of components of the steel thereby controlling precipitation of VN and MnS. A continuous casting slab with no surface cracks contains C, Si, Mn, P, S, Al, V, N, Ti, B, Ca and REM each within a specified range, and satisfies an equation for the relationship between V and N and a relationship between Mn and S.

Continuous casting slab suitable for the production of non-tempered high tensile steel material

A high tensile strength steel product for high heat input welding having excellent toughness in the heat-affected zone and having a tensile strength of at least 490 MPa contains, in terms of percent by weight, from about 0.05% to about 0.18% of C, 0.6% or less of Si, from about 0.80% to about 1.80% of Mn, 0.005% or less of Al, 0.030% or less of P, 0.004% or less of S, 0.005% or less of Nb, from about 0.04% to about 0.15% of V, from about 0.0050% to about 0.00150% of N, and from about 0.010% to about 0.050% of Ti, the ratio of the Ti content to the Al content, Ti/Al, satisfying 5.0 or more, and further contains at least one of from about 0.0010% to about 0.0100% of Ca and from about 0.0010% to about 0.0100% of REM, and the balance being Fe and incidental impurities. In the steel product, oxide inclusions containing, in terms of percent by weight, 20% to about 95% of a titanium oxide, 70% or less of Al O , 5% to about 50% in total of at least one of calcium oxide and a REM oxide, and 15% or less of MnO are dispersed.

High tensile strength steel product for high heat input welding, having excellent toughness in heat-affected zone

A high-strength and high-toughness steel product having at least about 0.001% and less than about 0.030% by weight C, not more than about 0.60% by weight Si, from about 0.8% to 3.0% by weight Mn, from about 0.005 to 0.20% by weight Nb, from about 0.0003 to 0.0050% by weight B, and not more than about 0.005% by weight AL wherein at least 90% of the product has a bainite structure. A method of making this steel product is subject to less stringent production controls because of the nature of the composition.

Method of producing a bainite steel product

The invention provides a steel product having superior weathering which is coated with a rust layer containing 50 or more weight % of non-crystalline rust, a method of producing the steel product, and a method of forming weathering protective rust on a material surface of the steel product. A material of a steel product is placed in an atmosphere in which the dew point is kept constant and the temperature of the steel product material is repeatedly varied between a temperature range of 5.degree. C. or more higher than the dew point and a temperature range of 5.degree. C. or more lower than the dew point. Weathering protective rust is thereby formed on the material surface of the steel product and a steel product having superior weathering is obtained. Preferably, the atmosphere contains 15 to 50 volume % of oxygen gas, and the temperature of the steel product is varied at a rising rate of 0.1 to 2.degree. C./minute and a lowering rate of 0.01 to 2.degree. C./minute. Alternatively, a desired steel product can also be obtained by placing a material of the steel product in an atmosphere containing 15 to 50 volume % of oxygen gas, keeping constant the dew point in the atmosphere, and keeping the temperature of the steel product material in the atmosphere at a certain value in a temperature range between a temperature 5.degree. C. lower than the dew point and a temperature 20.degree. C. lower than the dew point; or by placing a material of the steel product in an atmosphere containing 15 to 50 volume % of oxygen gas, and forming and keeping a water film with a thickness not more than 500 .mu.m but not less than 50 .mu.m on a material surface of the steel product.

Steel products having superior weathering, method of producing the steel

A high-strength heavy-wall H-shaped steel is excellent in Z-direction toughness at the flange thickness center. The heavy-wall H-shaped steel is comprised of by weight from about 0.05 to 0.18% C, up to about 0.60% Si, from about 1.00% to about 1.80% Mn, up to about 0.020% P, under 0.004% S, from 0.016% to 0.050% Al, from 0.04% to 0. 15% V, and from 0.0070% to 0.0200% N, and one or more of from about 0.02% to about 0.60% Cu, from about 0.02% to about 0.60% Ni, from about 0.02% to about 0.50% Cr, and from about 0.01% to about 0.20% Mo; and the balance being Fe and incidental impurities. Also, (V.times.N)/S.gtoreq.0.150; the Ti content is within a range satisfying 0.002.ltoreq.Ti.ltoreq.1.38.times.N-8.59.times.10.sup.-4 ; Ceq (=C+Si/24+Mn/6+Ni/40+Cr/5+Mo/4+V/14) is within a range of from about 0.36 wt % to about 0.45 wt %, and the yield strength is at least 325 MPa.

Heavy-wall H-shaped steel having high toughness and yield strength and

A method of manufacturing a thick steel product of high strength and high toughness having excellent weldability with minimal variation of material properties, comprises heating a steel raw material to the temperature of Ac.sub.3 to 1350.degree. C., hot rolling and then cooling at the cooling rate of 10.degree. C./sec. or less. The steel raw material has the following composition:

Method of manufacturing thick steel product of high strength and high

The present invention provides a hot-rolled steel sheet having a low yield ratio, a high specific strength, and excellent toughness. The hot-rolled steel sheet comprises: 0.005 to less than 0.030 weight percent of carbon, 1.5 weight percent or less of silicon, 1.5 weight percent or less of manganese, 0.020 weight percent or less of phosphorus, 0.015 weight percent or less of sulfur, 0.005 to 0.10 weight percent of aluminum, 0.0100 weight percent or less of nitrogen, 0.0002 to 0.0100 weight percent of boron, at least one element selected from the group consisting of 0.20 weight percent or less of titanium and 0.25 weight percent or less of niobium in an amount to satisfy (Ti+Nb/2)/C.gtoreq.4, and balance iron and incidental impurities. The metal structure is selected from the group consisting of ferrite and bainitic ferrite. The amount of carbon dissolved in grains ranges from 1.0 to 4.0 ppm. The present invention also provides a method for producing a hot-rolled steel sheet. The method includes hot-rolling a steel slab containing the above components, cooling at a rate of between 5 to not more than 20.degree. C./sec., and then coiling at a temperature ranging from over 550.degree. C. to 700.degree. C.

Hot-rolled steel sheet and method for forming hot-rolled steel sheet

This invention provides bainite steel materials having a less scattering of properties in a thickness direction or between steel materials by using a chemical composition of C: not less than 0.001 wt % but less than 0.030 wt %, Si: not more than 0.60 wt %, Mn: 1.00-3.00 wt %, Nb: 0.005-0.20 wt %, B: 0.0003-0.0050 wt % and Al: not more than 0.100 wt % and rendering not less than 90% of the material into a bainite texture in steel materials such as thick steel plates, steel sheets, section steels, rod steels and the like.

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Okayama, Japan

Fumimaru Kawabata