Kawasaki Steel Corporation

Jfe Steel Corporation

Eiko Yasuhara

Osamu Furukimi

Kei Sakata

Toshiyuki Kato

Akio Tosaka

Susumu Satoh

Takashi Yamauchi

Tadashi Inoue

Shigehiro Takajo

Masatoshi Kumagai

Saiji Matsuoka

Reiko Sugihara

Masahiko Morita

Susumu Okada

Kenji Tahara

Koichiro Fujita

Taro Kizu

Kazuhiro Hanazawa

Tatsuo Kawasaki

Takahiro Sugano

Kanji I

Nobuo Yamada

Takao Uchiyama

Nobuko Mineji

Hidetaka Kawabe

Hideharu Koga

A cold-rolled steel sheet includes, on a percent by mass basis: C: 0.0010% to 0.0030%, Si: 0.05% or less, Mn: 0.1% to 0.3%, P: 0.05% or less, S: 0.02% or less, Al: 0.02% to 0.10%, N: 0.005% or less, and Nb: 0.010% to 0.030% and the remainder composed of Fe and incidental impurities, wherein values in a rolling direction and a direction perpendicular to the rolling direction are within a range of 1.0 to 1.6, and a mean value Elof elongations in the rolling direction, a direction at 45&#xb0; with respect to the rolling direction, and the direction perpendicular to the rolling direction is 40% or more, where El=(El+2&#xd7;El+El)/4 and El: elongation in the rolling direction, El: elongation in the direction at 45&#xb0; with respect to the rolling direction, and El: elongation in the direction perpendicular to the rolling direction.

Cold-rolled steel sheet, method for manufacturing the same, and backlight chassis

A cold-rolled steel sheet has a composition containing, by mass percent, 0.0040% or less of C, 0.02% or less of Si, 0.14% to 0.25% of Mn, 0.020% or less of P, 0.015% or less of S, 0.0040% or less of N, 0.020% to 0.070% of Al, 0.005% to 0.030% of Nb, 0.005% to 0.030% of Ti, (0.0003% to 0.0010% of the equivalent amount of solid solution B (from which the amount of B forming BN has been subtracted)), and the balance composed of Fe and inevitable impurities, wherein even when the rolling reduction of cold rolling is 85% or less, the average grain size of a ferrite structure is reliably 12.0 &#x3bc;m or less, and the relationship &#x2212;0.20&#x2266;&#x394;r&#x2266;0.20 can be reliably satisfied and which has an excellent earing property.

Cold-rolled steel sheet, method of producing the same, battery, and method of producing the same

Continuous annealing equipment contains: a heating zone, a soaking zone, and a rapid cooling zone, the rapid cooling zone having gas jet cooling equipment and is provided with at least one pair of seal rolls at each of an inlet and an outlet thereof and bridle roll units each composed of two or more bridle rolls in front of and behind itself; the bridle roll unit behind the rapid cooling zone having two or more heating rolls each having an induction heater thereinside; and the heating roll having a winding angle of 100&#xb0; or more per heating roll and 380&#xb0; or more in total of all the heating rolls.

Continuous annealing equipment

The invention provides a thin high-strength hot-rolled steel sheet with a thickness of not more than 3.5 mm which has excellent stretch flangeability and high uniformity in both shape and mechanical properties of the steel sheet, as well as a method of producing the hot-rolled steel sheet. A slab containing C: 0.05-0.30 wt %, Si: 0.03-1.0 wt %, Mn: 1.5-3.5 wt %, P: not more than 0.02 wt %, S: not more than 0.005 wt %, Al: not more than 0.150 wt %, N: not more than 0.0200 wt %, and one or two of Nb: 0.003-0.20 wt % and Ti: 0.005-0.20 wt % is heated at a temperature of not higher than 1200&deg; C. The slab is hot-rolled at a finish rolling end temperature of not lower than 800&deg; C., preferably at a finish rolling start temperature of 950-1050&deg; C. A hot-rolled sheet is started to be cooled within two seconds after the end of the rolling, and then continuously cooled down to a coiling temperature at a cooling rate of 20-150&deg; C./sec. The hot-rolled sheet is coiled at a temperature of 300-550&deg; C., preferably in excess of 400&deg; C. A fine bainite structure is obtained in which the mean grain size is not greater than 3.0 &mgr;m, the aspect ratio is not more than 1.5, and preferably the maximum size of the major axis is not greater than 10 &mgr;m.

High-strength hot-rolled steel sheet having excellent stretch flangeability, and method of producing the same

A hot rolled steel sheet comprises ultrafine ferrite grains as a main phase and fine second phase particles. The ferrite grains have an average grain size of not less than 2 &mgr;m but less than 4 &mgr;m. The second phase has an average particle size of not more than 8 &mgr;m and in not less than 80% of the second phase, the spacing of the second phase particle with the closest second phase particle is not less than the second phase particle size. The steel sheet has an ultrafine grain structure, superior mechanical characteristics, reduced anisotropy in its mechanical characteristics and high formability. A process for producing the steel sheet is also disclosed.

Hot rolled steel sheet having an ultrafine grain structure and process for producing steel sheet

A hot rolled steel sheet with improved formability and producing method therefor, which can be easily produced with general hot strip mills, having less anisotropy of mechanical properties and final ferrite grain diameter of less than 2 &mgr;m that could not be achieved by the prior art. The hot rolled steel sheet comprises a ferrite phase as a primary phase, and has an average ferrite grain diameter of less than 2 &mgr;m, with the ferrite grains having an aspect ratio of less than 1.5. The hot rolled steel sheet is obtained by carried out a reduction process under a dynamic recrystallization conditions through reduction passes of not less than 5 stands in the hot finish rolling.

Hot rolled steel plate to be processed having hyper fine particles, method of manufacturing the same, and method of manufacturing cold rolled steel plate

A cold rolled steel sheet including about 0.001 weight percent or less of carbon (C), about 0.1 weight percent or less of silicon (Si), about 0.3 weight percent or less of manganese (Mn), about 0.05 weight percent or less of phosphorus (P), about 0.003 weight percent or less of sulfur (S), about 0.1 weight percent or less of aluminum (Al), about 0.002 weight percent or less of nitrogen (N), about 0.005 to 0.02 weight percent of titanium (Ti), about 0.001 to 0.01 weight percent of niobium (Nb), and the balance iron and incidental impurities. The total weight percent of carbon, sulfur, and nitrogen is about 0.004 weight percent or less. The content of titanium, carbon, sulfur and nitrogen satisfies the equation: about 4.times.(C wt %).ltoreq.(Ti wt %)-48/14(N wt %)-48/32(S wt %).ltoreq.about 12.times.(C wt %). The method of the invention includes uniformly heating a steel slab having a composition as described above at a temperature T(K) satisfying the following equation:

Cold rolled steel sheet exhibiting excellent press workability and

A method of manufacturing a cold rolled steel sheet includes the steps of preparing, as a material, a steel whose composition consists of C: 0.004 wt % or less, Si: 0.10 wt % or less, Mn: 0.50 wt % or less, Ti: between 0.01 wt % and 0.10 wt %, Nb: between 0.003 wt % and 0.03 wt %, B: between 0.001 wt % and 0.004 wt %, Al: between 0.03 wt % and 0.10 wt %, P: 0.025 wt % or less, S: 0.01 wt % or less, N: 0.006 wt % or less; performing a hot rolling on the material steel under the conditions of a finishing temperature between 800.degree. C. and 900.degree. C.; coiling the material at a temperature lower than 650.degree. C.; performing a cold rolling; performing a continuous annealing at a temperature between 830.degree. C. and Ac.sub.3 transformation point; and performing a skin pass rolling.

Method of manufacturing a low-alloy ultra-low-carbon cold anisotropy

In a method of producing a high-strength cold-rolled steel sheet excelling in deep drawability, a steel material is used which consists of: a basic composition including 0.01% or less of C, 0.1 to 2.0% of Si, 0.5 to 3.0% of Mn, 0.02 to 0.2% of P, 0.05% or less of S, 0.03 to 0.2% of Al, 0.01% or less of N, 0.001 to 0.2% of Nb, and 0.0001 to 0.008% of B in such a way that the respective contents of C, Nb, Al, N, Si, Mn and P satisfy the following formulae: 5.ltoreq.Nb/C.ltoreq.30, 10.ltoreq.Al/N.ltoreq.80, and 16.ltoreq.(3.times.Si/28+200 .times.P/31)/(Mn/55).ltoreq.40; Fe remnant; and inevitable impurities, the method including the steps of: performing rolling on the steel material with a total reduction of 50% or more and 95% or less while effecting lubrication thereon in a temperature range of not higher than the Ar.sub.3 transformation temperature and not lower than 500.degree. C.; performing a hot-rolled sheet recrystallization treatment on the steel material by a coiling or annealing process; performing cold rolling on the steel material with a reduction of 50 to 95%; and then effecting recrystallization annealing on the steel material in a temperature range of 700 .degree. to 950.degree. C.

High-strength cold-rolled steel sheet excelling in deep drawability and

A cold-rolled and annealed stainless steel strip is completely descaled in a short process period by electrolizing the strip with an aqueous solution containing ranges of

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Chiba, Japan

Eiko Yasuhara