Abstract: 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 Elm of elongations in the rolling direction, a direction at 45° with respect to the rolling direction, and the direction perpendicular to the rolling direction is 40% or more, where Elm=(ElL+2×ElD+ElC)/4 and ElL: elongation in the rolling direction, ElD: elongation in the direction at 45° with respect to the rolling direction, and ElC: elongation in the direction perpendicular to the rolling direction.

Abstract: 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 ?m or less, and the relationship ?0.20??r?0.20 can be reliably satisfied and which has an excellent earing property.

Abstract: 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° or more per heating roll and 380° or more in total of all the heating rolls.

Abstract: A cold-rolled steel sheet with excellent bending workability has a component composition of 0.025% or less C, 0.1% or less Si, 0.05% to 0.5% Mn, 0.03% or less P, 0.02% or less S, and 0.01% to 0.1% sol. Al on a mass basis, the remainder being Fe and unavoidable impurities; a microstructure that is a ferrite rolling texture; a tensile strength TS of 390 MPa or more; a thickness of 0.4 mm or more; and a sheet thickness direction ultimate ductility of 1.3 or more, wherein the sheet thickness direction ultimate ductility is the natural logarithm Ln(t0/t1) of the ratio of the thickness t0 of an untested steel sheet to the thickness t1 of the fracture surface of the tested steel sheet as determined by a tensile test.

Abstract: 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 r 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 Elm of elongations in the rolling direction, a direction at 45° with respect to the rolling direction, and the direction perpendicular to the rolling direction is 40% or more, where Elm=(ElL+2×ElD+ElC)/4 ElL: elongation in the rolling direction, ElD: elongation in the direction at 45° with respect to the rolling direction, and ElC: elongation in the direction perpendicular to the rolling direction.

Abstract: A cold-rolled steel sheet having superior non-ageing properties and low planar anisotropy can be produced at low cost without decreased productivity. This cold-rolled steel sheet contains, by mass, 0.010% to 0.040% carbon, 0.02% or less silicon, 1.0% to 2.5% manganese, 0.02% or less phosphorus, 0.015% or less sulfur, 0.004% or less nitrogen, and 0.020% to 0.070% aluminum, the balance being iron and incidental impurities. The steel sheet has a microstructure including a ferrite phase and a second phase. The volume percentage of the second phase is 0.2% to less than 10%. The steel sheet has an AI of 50 MPa or less, ?0.20??r?0.20, and a thickness of 0.5 mm or less.

Abstract: 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° or more per heating roll and 380° or more in total of all the heating rolls.

Abstract: 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 ?m or less, and the relationship ?0.20??r?0.20 can be reliably satisfied and which has an excellent earing property.

Abstract: 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° C. The slab is hot-rolled at a finish rolling end temperature of not lower than 800° C., preferably at a finish rolling start temperature of 950-1050° 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° C./sec. The hot-rolled sheet is coiled at a temperature of 300-550° C.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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:T(K).times.(C wt %+S wt %).ltoreq.

Abstract: 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.

Abstract: 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.

Abstract: 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 ofx (g/l)=50 to 270 (1)y (g/l)=(-0.01 x+3.8) to (-0.05x+21) (2),where x is concentration of nitric anid in g/l and y is concentration of chlorine in g/l.