Nippon Steel Sumitomo Metal Corporation

Nippon Steel Corporation

Hideaki Yamamura

Masafumi Miyazaki

Takashi Fujita

Masayuki Hashimura

Takeshi Kubota

Eiichiro Ishimaru

Yousuke Kurosaki

Kazuto Kawakami

Isao Suichi

Kenichi Yamamoto

Takeaki Wakisaka

Eiichi Takeuchi

Yasushi Kurisu

Kazumi Mizukami

Naoya Hamada

Hideki Oka

Mamoru Yamada

Tadahiro Izu

Kazumi Seki

Mitsuru Nakayama

Yasuo Maruki

Takashi Arai

Hiroshi Harada

Daisuke Maeda

Kaoru Kawasaki

Wataru Ohashi

Takahisa Suzuki

Osamu Kawano

Kenji Umetsu

Yoshihiro Suwa

Takehiko Toh

Yoshihiro Arita

Kenji Kosuge

Junji Haji

Yuzo Takahashi

Katsuhiro Sasai

Akihito Kiyose

Tooru Matsumiya

Satoru Mineta

Kohsuke Kume

A spring steel includes a predetermined chemical composition and a composite inclusion having a maximum diameter of 2 &#x3bc;m or more that TiN is adhered to an inclusion containing REM, O and Al, in which the number of the composite inclusion is 0.004 pieces/mmto 10 pieces/mm, the maximum diameter of the composite inclusion is 40 &#x3bc;m or less, the sum of the number density of an alumina cluster having the maximum diameter of 10 &#x3bc;m or more, MnS having the maximum diameter of 10 &#x3bc;m or more and TiN having the maximum diameter of 1 &#x3bc;m to 10 pieces/mm.

Spring steel with excellent fatigue resistance and method of manufacturing the same

A steel for induction hardening includes as a chemical composition, by mass %, C: 0.45% to 0.85%, Si: 0.01% to 0.80%, Mn: 0.1% to 1.5%, Al: 0.01% to 0.05%, REM: 0.0001% to 0.050%, O: 0.0001% to 0.0030%. Ca: 0.0050% or less as necessary, Ti: less than 0.005%, N: 0.015% or less, P: 0.03% or less, S: 0.01% or less, and the balance consists of Fe and impurities. The steel for induction hardening also includes a composition inclusion which is an inclusion containing REM, O, S, and Al, or an inclusion containing REM, Ca, O, S, and Al, to which TiN is adhered.

Steel for induction hardening with excellent fatigue properties

A case hardening steel includes as a chemical composition, by mass %, C: 0.10% to 0.40%, Si: 0.01% to 0.80%, Mn: 0.1% to 1.5%, Cr: 0.35% to 2.0%, Al: 0.01% to 0.05%, REM: 0.0001% to 0.050%, O: 0.0001% to 0.0030%, Ca: 0.0050% or less as necessary, Ti: less than 0.005%, N: 0.015% or less, P: 0.03% or less, S: 0.01% or less, and the balance consists of Fe and impurities. The case hardening steel also includes a composition inclusion which is an inclusion containing REM, O, S, and Al, or an inclusion containing REM, Ca, O, S, and Al, to which TiN is adhered.

Case hardening steel with excellent fatigue properties

A bearing steel includes, as a metallographic structure, inclusions which contain complex oxysulfides including Rare Earth Metal, Ca, O, S, and Al, TiN, MnS, AlO, and complex oxides including Al and Ca, wherein, a number fraction of the complex oxysulfides in a total number of the inclusions is 50% to less than 100% and a number of complex oxysulfides having a major axis of 5 &#x3bc;m or more is 0.001 pieces to 2 pieces in an observed section of 1 mm, and a number of TiN existing independently from the complex oxysulfides and having a major axis of 5 &#x3bc;m or more is 0.001 pieces to less than 1.0 piece in an observed section of 1 mm.

Bearing steel and method for producing same

A high-strength steel sheet includes: 0.03 to 0.20% of C, 0.08 to 1.5% of Si, 0.5 to 3.0% of Mn, 0.05% or less of P, 0.0005% or more of S, 0.008 to 0.20% of acid-soluble Ti, 0.0005 to 0.01% of N, more than 0.01% of acid-soluble Al, and 0.001 to 0.04% of one or both of Ce and La in terms of mass %; and the balance including Fe and inevitable impurities. The ratio of (Ce+La)/acid-soluble Al is equal to or more than 0.1 and the ratio of (Ce+La)/S is in the range of 0.4 to 50 in a mass base, and the density of the number of inclusions, having a circle equivalent diameter of 2 &#x3bc;m or less, which are present in the steel sheet is equal to or more than 15/mm.

High-strength steel sheet and method of producing molten steel for high-strength steel sheet

The present invention provides a high-strength steel sheet including: C: 0.03 to 0.25 mass %, Si: 0.1 to 2.0 mass %, Mn: 0.5 to 3.0 mass %, P: not more than 0.05 mass %, T.O: not more than 0.0050 mass %, S: 0.0001 to 0.01 mass %, N: 0.0005 to 0.01 mass %, acid-soluble Al: more than 0.01 mass %, Ca: 0.0005 to 0.0050 mass %, and a total of at least one element of Ce, La, Nd, and Pr: 0.001 to 0.01 mass %, with a balance including iron and inevitable impurities, in which the steel sheet contains a chemical component on a basis of mass that satisfies 0.7&#x3c;100&#xd7;([Ce]+[La]+[Nd]+[Pr])/[acid-soluble Al]&#x2266;70 and 0.2&#x2266;([Ce]+[La]+[Nd]+[Pr])/[S]&#x2266;10, the steel sheet contains compound inclusion including a first inclusion phase containing at least one element of Ce, La, Nd, and Pr, containing Ca, and containing at least one element of O and S, and a second inclusion phase having a component different from that of the first inclusion phase and containing at least one element of Mn, Si, and Al, the compound inclusion forms a spherical compound inclusion having an equivalent circle diameter in the range of 0.5 &#x3bc;m to 5 &#x3bc;m, and a ratio of the number of the spherical compound inclusion relative to the number of all inclusions having the equivalent circle diameter in the range of 0.5 &#x3bc;m to 5 &#x3bc;m is 30% or more.

High-strength steel sheet exhibiting excellent stretch-flange formability and bending workability, and method of producing molten steel for the high-strength steel sheet

A non-oriented electrical steel sheet comprising, Si: not less than 1.0 mass % nor more than 3.5 mass %, Al: not less than 0.1 mass % nor more than 3.0 mass %, Ti: not less than 0.001 mass % nor more than 0.01 mass %, Bi: not less than 0.001 mass % nor more than 0.01 mass %, wherein Expression (1) is satisfied when a Ti content (mass %) is represented as [Ti] and a Bi content (mass %) is represented as [Bi]: [Ti]&#x2266;0.8&#xd7;[Bi]+0.002 . . . (1).

Non-oriented electrical steel sheet and manufacturing method thereof

A low-carbon steel slab producing method includes: adding Ti to a molten steel decarbonized to have a carbon concentration of 0.05 mass % or less, and subsequently adding at least one of La and Ce to adjust a constitution, and producing a smelted molten steel; and pouring the smelted molten steel into a casting mold via a tundish; wherein at least one of La and Ce in a total amount of 0.2 to 1.2 times an increased amount of oxygen in the smelted molten steel during contained in the tundish is added to the smelted molten steel in the tundish, so as to obtain a steel slab having inclusions which contain oxides of Ti and at least one of La and Ce as chief components, and so as to make a composition of each of the inclusions have a mass ratio of 0.1 to 0.7, in terms of (LaO+CeO)&#xf7;TiO(n=1&#x2dc;2).

Low-carbon steel slab producing method

In a non-oriented electrical steel sheet, Si: not less than 1.0 mass % nor more than 3.5 mass %, Al: not less than 0.1 mass % nor more than 3.0 mass %, Ti: not less than 0.001 mass % nor more than 0.01 mass %, Bi: not less than 0.001 mass % nor more than 0.01 mass %, and so on are contained. (1) expression described below is satisfied when a Ti content (mass %) is represented as [Ti] and a Bi content (mass %) is represented as [Bi].[Ti]&#x2266;0.8&#xd7;[Bi]+0.002&#x2003;&#x2003;(1)

A non-oriented electrical steel sheet, containing: C: 0.01 mass % or less; Si: 1.0 mass % or more and 3.5 mass % or less; Al: 0.1 mass % or more and 3.0 mass % or less; Mn: 0.1 mass % or more and 2.0 mass % or less; P: 0.1 mass % or less; S: 0.005 mass % or less; Ti: 0.001 mass % or more and 0.01 mass % or less; N: 0.005 mass % or less; and Y: more than 0.05 mass % and 0.2 mass % or less, with the balance being iron and inevitable impurities.

Non-oriented electrical steel sheet

A continuous casting device for steel of the present invention includes a casting mold for casting a molten steel, a submerged entry nozzle, an electromagnetic stirring device, and an electromagnetic brake device. Further, a curved portion which is curved toward the electromagnetic stirring device is formed at least at a position where the curved portion faces the submerged entry nozzle, on each of the long side walls. Moreover, the horizontal distance between a top of the curved portion and the submerged entry nozzle in plan view is equal to or more than 35 mm and less than 50 mm.

Continuous casting apparatus for steel

The present invention provides tough cast iron and cast iron semi-finished products excellent in workability without heat treatment requiring massive heat energy and long time and a method of production enabling these to be efficiently produced, that is, cast iron of ingredients of white cast iron where particles of spheroidal graphite or flattened graphite are dispersed, cast iron where the ingredients of the white cast iron satisfy, by wt %, (% C)&#x2266;4.3&#x2212;(% Si)&#xf7;3 and C&#x2267;1.7% and where the particles of spheroidal graphite are dispersed at a density of 50 particles/mmor more, or cast iron where the particles of flattened graphite have a width of 0.4 mm or less and a length of 50 mm or less.

Cast iron semi-finished product excellent in workability and method of production of the same

A steel product for welding includes the following component: by mass %, C: 0.3% or less, Si: 0.5% or less, Mn: 0.3&#x2dc;2%, P: 0.03% or less, S: 0.03% or less, Al: 0.3&#x2dc;5%, O: 0.003&#x2dc;0.01%, and N: 0.006% or less; wherein the balance is composed of Fe and inevitable impurities; wherein Al-containing oxides having a size of 0.005 to 0.05 &#x3bc;m are dispersed in steel at a ratio of 1&#xd7;10/mmor more.

Steel product for welding

A quench solidification method, wherein a steel cast strip having a mean grain size 50 &#x3bc;m or more is prepared and then the steel cast strip is rolled to produce a non-oriented electrical steel sheet having high magnetic flux density in both L and C directions. However the magnetic flux density reduces when the cold reduction rate exceeds 70%. To avoid this problem the non-oriented electrical steel sheet is manufactured with a ratio of at least 4 of the integrated intensity of the {100} plane for a given sample of steel to the integrated intensity of {100} plane for a 'random' sample in which crystal grains have random orientations; and a cold reduction rate of the cold-rolling is between 70% and 85%. The superheating degree of the molten steel can be 70&#xb0; C. or more.

Method for manufacturing non-oriented electrical steel sheet having high magnetic flux density

A cooling drum for metal cast strip by continuous casting has dimples 40 to 200 &#x3bc;m in average depth and 0.5 to 3 mm in diameter of circle equivalent formed on a plated peripheral surface of the cooling drum, adjacent to each other at rims of the dimples; and a film, containing oxides of at least one member selected from the group consisting of Ni&#x2014;W, Ni&#x2014;Co&#x2014;W, Cr, Ni&#x2014;Fe and Ni&#x2014;Al, is formed on the peripheral surface.

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Tokyo, Japan

Hideaki Yamamura