Nippon Steel Corporation

Osamu Akisue

Naoki Yoshinaga

Kohsaku Ushioda

Teruaki Yamada

Kunio Nishimura

Koji Kishida

Teruki Hayashida

Hiroshi Katoh

Yoshikazu Matsumura

Yasumitsu Onoe

Toshiyasu Ukena

Shuichi Yamazaki

Manabu Takahashi

Tohru Yoshida

Hisashi Mogi

Masahiro Fujikura

Hidekuni Murakami

Munetsugu Matsuo

Masato Yamada

Masato Mizokami

Matsuo Usuda

Kishio Mochinaga

Masao Yabumoto

Atsuhiro Wakako

Yoshikuni Tokunaga

Kichi Nakazawa

Masahiko Oda

Masakazu Oshimi

Tomohisa Katayama

Yuuji Sano

Koichi Kawamura

Kenji Kawai

Norimasa Uehara

Seiryo Hatae

Hiroaki Toki

Shigeru Ueda

The present invention provides an electrical steel sheet core for a low-noise transformer capable of effectively lowering noise by suppressing vibration perpendicular to the surfaces of the steel sheets and reducing vibration, and relates to an electrical steel sheet for a low-noise transformer characterized by randomly inserting viscoelastic layers with both viscosity and elasticity into the gaps of the steel sheet lamination layers, and a low-noise transformer formed by using said electrical steel sheet.

Electrical steel sheet for low-noise transformer and low-noise transformer

A thin ferritic steel sheet having an excellent shape fixability capable of being used for bending is provided, comprising: at least 0.027 to less than 0.05 mass % of C, 0.01 to 1.0 mass % of Si, 0.01 to 2.0 mass % of Mn, not more than 0.15 mass % of P, not more than 0.03 mass % of S, 0.01 to 0.1 mass % of Al, not more than 0.01 mass % of N, not more than 0.007 mass % of O, the balance being Fe and inevitable impurities, wherein a ratio of presence of &lcub;100&rcub; planes parallel with a face of the steel sheet to &lcub;111&rcub; planes is not less than 1.0, and TS&times;El, which represents a product of maximum tensile strength (TS) multiplied by rupture elongation (El) of the steel sheet, is at least 13,860 MPA %.

Ferrite-based thin steel sheet excellent in shape freezing feature and manufacturing method thereof

The present invention provides a cold-rolled steel sheet and a hot-dip galvanized steel sheet having good bake hardenability, non-aging properties at room temperature and good formability and a process for producing the same. An extra low carbon steel or an extra low carbon steel containing at least one element selected from Ti and Nb is annealed at a temperature of not lower than the AC.sub.3 transformation point to bring the structure after annealing to a structure of low-temperature transformation products. This makes it possible to provide a steel sheet that has a combination of high paint-bake hardenability and non-aging properties at room temperature and is excellent also in formability in respect of average r value (deep drawability) and elongation (punch stretchability). In particular, with respect to paint-bake hardenability, a BH property on a high level up to about 10 kgf/mm.sup.2 can be imparted according to need, and it is possible to provide a cold-rolled steel sheet and a hot-dip galvanized cold-rolled steel sheet that also have a non-aging property at room temperature.

Cold-rolled steel sheet and hot-dip galvanized cold-rolled steel sheet

Non-aging at room temperature ferritic single-phase cold-rolled steel

Cold rolled steel sheet and hot dip zinc-coated cold rolled steel sheet

High-strength cold-rolled steel strip and molten zinc-plated

A process for producing a non-aging galvanized steel sheet having good formability in a continuous galvanizing production line, which comprises heating a low carbon, Al-killed cold rolled steel sheet at a temperature not lower than a recrystallizing temperature, reducing the surface of the steel sheet thus heated in a reducing atmosphere, cooling the steel sheet to a temperature (T.sub.E) ranging from 200.degree. to 350.degree. C. from a temperature not lower than 600.degree. C. at a cooling rate not less than 30.degree. C/s, holding the steel sheet at the temperature (T.sub.E) for 0 to less than 10 seconds, reheating the steel sheet to a temperature ranging from 430.degree. to 500.degree. C. at a heating rate not less than 10.degree. C/s, immersing the steel sheet into a molten zinc bath, cooling the steel sheet thus galvanized to a temperature not higher than 370.degree. C., and subjecting the steel sheet to an overaging treatment to a temperature range from 250.degree. to 320.degree. C. for not shorter than 40 seconds. A modified process according to the present invention further comprises reheating the galvanized steel sheet to a temperature raning from 480.degree. to 600.degree. C. at a heating rate not lower than 10.degree. C/s, and holding the sheet in this temperature range to perform alloying of the zinc coating layer with the steel substrate.

Process for producing galvanized, non-aging cold rolled steel sheets

High-strength cold-rolled steel sheet having high r value and process

A zinc-plated steel sheet with an ageing resistance is produced from an Al-killed steel by hot dip type, continuous zinc plating including recrystallization and annealing, where after recrystallization and grain growth, the steel sheet is quenched at a cooling rate of 30.degree..about.250.degree. C/sec from 720.degree..about.600.degree. C. to 310.degree..about.200.degree. C.; after keeping the steel sheet at the same temperature for 0 to 15 seconds, the steel sheet is reheated to a molten zinc bath temperature; then the steel sheet is dipped into the molten zinc bath for zinc-plating; and then the steel sheet is cooled at a cooling rate of 250 to 5.degree. C./sec from that temperature to 350.degree. C.; and then the steel sheet is cooled at a specific average cooling rate in a temperature region of 350.degree. C. to 300.degree. C. and at a specific average cooling rate in a temperature region of from 300.degree. C. to 285.degree..about.220.degree. C.

Process for producing a zinc-plated steel sheet with an ageing

A cold rolled steel sheet having a good ageing resistance is produced by subjecting a cold rolled steel sheet to continuous annealing including recrystallization, grain growth, quenching, supercooling, reheating and overageing according to inclinatory cooling, where after the recrystallization and the grain growth, the steel sheet is quenched at a cooling rate of 50 to 250.degree. C./sec from 720-600.degree. C. to 200-310.degree. C.; after retaining the steel sheet at the same temperature for 0 to 15 seconds, the steel sheet is reheated by at least 40.degree. C. up to 320-400.degree. C.; then the steel sheet is retained at the same temperature or cooled at a rate of not more than 0.7.degree. C./sec including the time for retaining the steel sheet at the same temperature; and then the steel sheet is cooled at an average cooling rate of not more than 10.degree. C./sec in a temperature zone of higher than 350.degree. C., at a specific average cooling rate in a temperature zone of 350.degree. C. to 300.degree. C. and at a specific average cooling rate down to 285-220.degree. C. in a temperature zone of lower than 300.degree. C.

Process for producing a cold rolled steel sheet having a good ageing

High-strength hot-rolled steel sheet having remarkably excellent cold

Disclosed is a process for producing titanium-containing cold rolled steel sheets and strips which can stand very severe press forming, which process comprising hot rolling, coiling at a temperature not lower than 700.degree. C., cold rolling and continuous annealing at a temperature, from 700.degree. to 900.degree. C., for 20 seconds to 2 minutes.

Process for producing deep-drawing cold rolled steel sheets and strips

In a method for producing a cold-rolled steel sheet by continuously casting, hot-rolling, cold-rolling, and continuously annealing Al-killed steel, it is known to coil a hot-rolled strip at a coiling temperature of 630.degree. C. to 710.degree. C. so as to attain satisfactory precipitation of AlN in the hot-rolling step. When the direct-rolling of a continuously cast strand (DR method) is employed to produce a cold-rolled strip, it is impossible to attain satisfactory precipitation of AlN even by carrying out the known coiling method. The present invention is characterized in that an extremely high coiling temperature of at least 780.degree. C. is used to essentially prevent aging due to the precipitation of AlN, and, further, the carbon content of a continuously cast slab is 0.005% at the highest so as to essentially prevent the occurrence of orange peel. Heat conservation due to use of the DR method and excellent properties of the cold-rolled steel strip are simultaneously attained.

Method for producing a cold-rolled steel sheet having excellent

A method of producing a non-ageing cold rolled steel strip having excellent deep-drawability, with a r value of 1.5 or higher and ageing index of not higher than 3 kg/mm.sup.2 from an Al-killed steel with a lowered carbon content between 0.001 and 0.0035% and with no special additives such as titanium by a relatively low temperature coiling in the hot rolling, and a short-time continuous annealing without over-ageing, thus over-coming the disadvantages caused by a high temperature coiling and by additional over-ageing.

Method of producing non-ageing cold rolled steel strip with excellent

A method for producing a low carbon deep drawing quality steel or high strength steel in the form of a strip or sheet. At least one of carbide or nitride forming elements is added to the low carbon steel to provide therein 0.015 to 0.10% Sol Al, 0.01 to 0.10% Nb, 0.01 to 0.10% Ti and 0.01 to 0.15% V. The steel is cast or bloomed to form a slab which is held above the Ar.sub.3 point for keeping the carbide and nitride forming elements in a dissolved state. Then, without allowing the temperature to fall below the Ar.sub.3 point, hot rolling and hot finishing rolling are directly carried out at a temperature above the Ar.sub.3 point. Thereafter, if necessary and desirable, the thus-rolled slab or sheet is subjected to cold rolling and annealing.

Method for producing steel strip or steel sheet containing carbide and

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Futtsu, Japan

Osamu Akisue