HOCHZUGFESTES WARMGEWALZTES STAHLBLECH MIT HERVORRAGENDER MASSHALTIGKEIT UND HERVORRAGENDEN DAUERFESTIGKEITSEIGENSCHAFTEN NACH DEM FORMEN

HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLING IN DEEP DRAWABILITY AND METHOD OF PRODUCING THE SAME

GALVANIZED HIGH-STRENGTH STEEL SHEET HAVING LOW YIELD RATIO AND METHOD OF PRODUCING THE SAME

Disclosed is a galvanized steel sheet which has a tensile strength of not less than 80 kgf/mm2 and a yield ratio of not more than 60%, and which is applicable to members of an automobile body, particularly those requiring strength. By appropriately controlling the amounts of C within the range of 0.08-0.20 wt%, Mn within the range of 1.5-3.5 wt%, Al within the range of 0.01-0.1 wt%, P 0.01 wt% or less, S 0.01 wt% or less, and one or both of Ti and Nb within the range of 0.01-0.1 wt%, the structure of the steel sheet is formed into a dual-phase structure having a second phase structure. The steel sheet is recrystallization-annealed, galvanized while it is maintained at a temperature range near 500.degree.C, and then is cooled. By controlling the rate of cooling the steel sheet, the second phase structure generated is prevented from hardening more than necessary. The galvanized high-strength steel sheet has a low yield ratio and excellent stretch-flanging properties.

HIGH STRENGTH THIN STEEL SHEET, HIGH STRENGTH GALVANNEALED STEEL SHEET AND MANUFACTURING METHOD THEREOF

A high strength thin steel sheet which comprises 0.01 to 0.20 wt % of C, 1.0 wt % or less of Si, 1.0 to 3.0 wt % of Mn, 0.10 wt % or less of P, 0.05 wt % or less of S, 0.10 wt % or less of Al, 0.010 wt % or less of N, 1.0 wt % or less of Cr, and 0.001 to 1.00 wt % of Mo, the residue of the sheet being comprised of Fe and obligatory impurities, and has a band structure consisting of two layers and having a thickness satisfying the relationship: Tb/T0.005, wherein Tb represents a mean thickness of the band structure in the thickness direction of the sheet and T represents a thickness of the sheet, and a method for producing the steel sheet; and a high strength hot-dip zinc-coated steel sheet or a high strength alloyed hot-dip zinc-coated steel sheet which is produced by subjecting the high strength thin steel sheet to zinc plating or alloying and zinc plating. The above high strength thin steel sheet is excellent in workability and capability of being metal-plated, and the above high strength ...

Verfahren zum Herstellen leicht verformbarer, hochfester, kaltgewalzter Stahlbleche mit guter Beständigkeit gegen Versprödung durch Weiterbearbeitung

Galvanisierter Stahl mit niedrigem Verhältnis der Elastizitätsgrenze zur Bruchfestigkeit und Verfahren zur Herstellung

Kaltgewalztes hochfestes Stahlblech mit hervorragender Tiefziehfähigkeit

WARM, COLD-ROLLING AND FUSIONGALVANIZED STEEL PLATE WITH EXCELLENT STRAINING AGING BEHAVIOR

Method of producing seam-welded pipe having good welded portion characteristics

Composite structure type high tensile strength steel plate, plated plate of composite structure type high tensile strength steel and method for their production

HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLING IN DEEP DRAWABILITY AND METHOD OF PRODUCING THE SAME

HIGH STRENGTH COLD ROLLED STEEL SHEET HAVING EXCELLENT NON-AGING PROPERTY AT ROOM TEMPERATURE AND SUITABLE FOR DRAWING AND METHOD OF PRODUCING THE SAME

Disclosed is a high strength cold rolled steel sheet having excellent non-aging property at room temperature and excellent drawability. The steel sheet has a dual-phase structure composed of a high-temperature transformed ferrite phase and a low-temperature transformed ferrite phase having high dislocation density and a composition by weight % of 0.001 to 0.025 C; not more than 1.0 Si; 0.1 to 2.0 Mn; 0.001 to 0.2 Nb; 0.0003 to 0.01 B; 0.005 to 0.10 Al; not more than 0.1 P, not more than 0.007 N; at least of 0.05 to 3.0 Ni; 0.01 to 2.0 wt% of Mo and 0.05 to 5.0 wt% of Cu, and the balance substantially Fe.

MODULATORS OF TRK PROTEIN ACTIVITY, COMPOSITIONS AND USES

The present invention concerns receptor tyrosine kinases and ligands therefore that modulate cell growth, differentiation, and survival. Particularly, the present invention concerns the TrK family of receptor tyrosine kinases known to mediate the activities of neurotrophins. TrK proteins are also known proto-oncogenes. Small molecule compositions for the modulation of TrK protein binding and activity are provided. Also provided are methods for screening for small molecules capable of binding to TrK protein binding one or more neurotrophin binding determinants in TrK proteins. © KIPO & WIPO 2007 ...

Hochduktiles Stahlblech mit exzellenter Pressbarkeit und Härtbarkeit durch Verformungsalterung sowie Verfahren zu dessen Herstellung

HEISSGETAUCHTES GALVANISIERTES STAHLBLECH MIT HOHER FESTIGKEIT UND HERVORRAGENDEN EIGENSCHAFTEN BEIM UMFORMEN UND GALVANISIEREN

Zugfestes warmgewalztes Stahlblech mit ausgezeichneter Bruchdehnung und Streckbördelverformfähigheit und dessen Herstellungsverfahren

HOCHDUKTILES STEEL SHEET WITH MORE EXCELLENT PRESSBARNESS AND HARDENABILITY BY DEFORMATION AGING AS WELL AS PROCEDURE FOR ITS PRODUCTION

PROCESS FOR PRODUCING HIGH TENSILE HOT-DIP ZINC-COATED STEEL SHEET OF EXCELLENT DUCTILITY AND ANTIFATIGUE PROPERTIES

High tensile hot-dip zinc-coated steel plate excellent in ductility and method for production thereof

Galvanized High-Strength Steel Sheet Having Low Yield Ratio and Method of Producing the Same

High-tensile strength hot-rolled steel sheet excellent in elongation properties and stretch flangeability and producing method thereof

Thick cold rolled steel sheet excellent in deep drawability and method of mfg. same

Hot-rolled steel sheet and process for producing the same

EXPANSIBLE TUBULAR ARTICLES WITHOUT SEAM FOR OIL FIELDS AND A METHOD OF PRODUCTION OF THE SAME

La presente brinda un artículo tubular expansible sin costura para campos petrolíferos, el cual tiene una propiedad de expansion de tubo superior en un proceso de expansion a una razon de expansion de más del 30% aunque tiene una alta resistencia, tal como una resistencia a la traccion de 600 MPa o más, y un método de produccion de los mismos, el artículo tubular expansible sin costura para campos petrolíferos se encuentra tal como sales de la laminadora o se procesa, segun sea necesario, mediante el poco costoso tratamiento térmico de refinacion no térmica. Un producto en particular contiene 0,001% o menos de 0,10% de C, entre 0,05% y 1% de Si, entre 0,5% y 4% de Mn, 0,03% o menos de P, 0,015% o menos de S, entre 0,01% y 0,06% de Al, 0,007% o menos de N, y 0,005% o menos de O, y contiene al menos uno de Nb, Mo y Cr, en una cantidad que oscila entre 0,01% y 0,2% de Nb, entre 0,05% y 0,5% de Mo, y entre 0,05% y 1,5% de Cr, por lo que se satisfacen Mn + 0,9 x Cr + 2,6 x Mo mayor o igual 2,0 ...

Process for producing high tensile hot-dip zinc-coated steel sheet of excellent ductility and antifatigue properties

HOCHFESTE FEUERVERZINKTE STAHLPLATTE MIT HERVORRAGENDEN PLATTIERUNGSEIGENSCHAFTEN UND HERSTELLUNGSVERFAHREN

High-strength cold-rolled steel sheet excelling in deep drawability and method of producing the same

Cold-rolled steel sheet having ultrafine grain structure and method for manufacturing the same

EMBRITTLEMENT RESISTANT ULTRA DEEP DRAWING HOT ROLLED STEEL

HIGH-TENSILE STRENGTH WELDED STEEL TUBE FOR STRUCTURAL PARTSOF AUTOMOBILES AND METHOD OF PRODUCING THE SAME

A high-tension welded steel pipe for automotive structural members which has excellent formability and has excellent resistance to torsional fatigue after section forming and subsequent annealing for stress removal; and a pro cess for producing the steel pipe. A raw steel material having a composition which contains C, Si, and Al in amounts in respective proper ranges and fur ther contains 1.01-1.99% Mn, 0.041-0.150% Ti, and 0.017-0.150% Nb, provided that Ti+Nb is 0.08% or more, and in which the amounts of P, S, N, and O have been regulated so as to be not larger than given values is subjected to hot rolling in which the heating temperature and the finish-rolling completion temperature are in proper ranges. After completion of the hot rolling, the s teel material is annealed in a temperature range of 750-650°C for 2 seconds or longer. The steel is then wound at a winding temperature of 660-510°C to obtain a hot-rolled steel strip comprising at least 60 vol.% ferrite phase h aving an average ...

HOT ROLLED STEEL SHEET HAVING HIGH RESISTANCES AGAINST SECONDARY-WORK EMBRITTLEMENT AND BRAZING EMBRITTLEMENT AND ADAPTED FOR ULTRA-DEEPDRAWING AND A METHOD FOR PRODUCING THE SAME

HOT ROLLED STEEL SHEET HAVING HIGH RESISTANCES AGAINST SECONDARY-WORK EMBRITTLEMENT AND BRAZING EMBRITTLEMENT AND ADAPTED FOR ULTRA-DEEP DRAWING AND A METHOD FOR PRODUCING THE SAME A hot rolled steel sheet having a specifically limited composition and having a specifically limited small particle size of ferrite constituting the steel sheet has high resistances against secondary-work embrittlement and brazing embrittlement and is adapted for ultra-deep drawing. The specifically limited small particle size of the ferrite can be obtained by limiting specifically the hot rolling condition of a slab having the specifically limited composition.

HOT ROLLED STEEL SHEET AND ITS PRODUCTION PROCESS

After a starting material of steel comprising C: 0.001- 0.20 wt%, Si: 0.01-0.50 wt%, Mn: 0.05-2.0 wt%, P: not more than 0.05 wt%, S: not more than 0.05 wt%, sol.Al: 0.01-0.10 wt%, N: not more than 0.020 wt% and.the balance being Fe and inevitable impurities is heated above Ac3 point, rough rolling is completed within a temperature range of (Ar3 point + 100.degree.C) - (Ar3 point + 50.degree.C), and super-high pressure descaling is carried out under conditions satisfying a jetting pressure of not less than 25 kgf/cm2 and a liquid quantity density of not less than 0.002 liter/cm2, and subsequently finish rolling at a rolling reduction of not less than 80% above Ar3 point of a rolling completion temperature is started in 5 seconds and coiling is carried out below 700.degree.C, whereby hot rolled steel sheets having a surface roughness Ra of not more than 0.8 .mu.m and an average scale thickness of not more than 4 .mu.m is produced and the adhesion property in case of subjecting to shaping ...

HIGH STRENGTH STEEL SHEET ADAPTED FOR PRESS FORMING AND METHOD OF PRODUCING THE SAME

A high strength steel sheet adapted for press forming and method producing the same. The steel sheet containing by weight C: 0.01-0.1%, Si: 0.1-1.2%; Mn: not more than 3.0%, Ti:a value of (Ti%-1.5S%-3.43N%)/C% being 4-12, B: 0.0005-0.005%, Al: not more than 0.1%, P: not more than 0.1%, S: not more than 0.02%, N: not more than 0.05%. The method for producing the steel sheet wherein a steel slab containing the above mentioned component composition is heated and hot rolled in a temperature range of 1100-1280.degree.C to provide a hot rolled sheet. The hot rolled sheet may be is subjected to cold rolling and annealing to provide a cold rolled sheet.

HIGH-STRENGTH HIGH-WORKABILITY COLD ROLLED STEEL SHEET HAVING EXCELLENT IMPACT RESISTANCE

A high-strength high-workability cold rolled steel sheet having excellent impact resistance, containing 0.05 to 0.40 mass % of C, 1.0 to 3.0 mass % of Si, 0.6 to 3.0 mass % of Mn, 0.02 to 1.5 mass % of Cr, 0.010 to 0.20 mass % of P, 0.01 to 0.3 mass % of Al and the balance substantially consisting of Fe, characterized in that the sheet comprises a ferrite (polygonal ferrite) as the primary phase and a second phase consisting of martensite, acicular ferrite and residual austenite, the ratio of the second phase in the steel structure being 3 to 40 %, the ratio of martensite in the second phase being 10 to 80 %, the ratio of the residual austenite being 8 to 30 % and the ratio of the acicular ferrite being 5 to 60 %. This sheet is excellent in impact resistance, and not only has a sufficient formability but also can withstand strict safety standards mainly as an automobile steel sheet. © KIPO & WIPO 2007 ...

HIGH-DUCTILITY STEEL SHEET EXCELLENT IN PRESS FORMABILITY AND STRAIN AGE HARDENABILITY, AND METHOD FOR MANUFACTURING THE SAME

PURPOSE: Provided is a high-ductility steel sheets having very high strain age hardenability and excellent press formability such as ductility, stretch-flanging formability, and drawability, in which the tensile strength increases remarkably through a heat treatment after press forming. CONSTITUTION: The steel sheet composition contains appropriate amounts of C, Si, Mn, P, S, Al and N and 0.5 to 3.0% Cu. A composite structure of the steel sheet has a ferrite phase or a ferrite phase and a tempered martensite phase as a primary phase, and a secondary phase containing retained austenite in a volume ratio of not less than 1%. In place of the Cu, at least one of Mo, Cr, and W may be contained in a total amount of not more than 2.0%. This composition is useful in production of a high-ductility hot-rolled steel sheet, a high-ductility cold-rolled steel sheet and a high-ductility hot-dip galvanized steel sheet having excellent press formability and excellent stain age hardenability as represented ...

Cold-rolled steel sheet having ultrafine grain structure and method for manufacturing the same

KALTGEWALZTES, DICKES STAHLBLECH MIT HERVORRAGENDEN TIEFZIEHEIGENSCHAFTEN UND VERFAHREN ZU DESSEN HERSTELLUNG

HOCHFESTES KALTGEWALZTES STAHLBLECH MIT HERVORRAGENDER DUKTILITÄT UND RECKALTERUNGSEIGENSCHAFTEN UND HERSTELLUNGSVERFAHREN DAFÜR

Composite structure type high tensile strength steel plate, plated plate of composite structure type high tensile strength steel and method for their production

Hot rolled steel plate, cold rolled steel plate and hot dip galvanized steel plate being excellent in strain aging hardening characteristics, and method for their production

COLD-ROLLED THICK SHEET STEEL WITH GOOD DEEP DRAWABILITY, AND METHOD FOR PRODUCING IT

A thick cold rolled steel sheet having an r value of not less than 2.9 even when the thickness is not less than 1.2 mm; and a method of manufacturing the same, comprising: rough hot-rolling a steel slab which contains not more than 0.008 wt.% of C, not more than 0.5 wt.% of Si, not more than 1.0 wt.% of Mn, not more than 0.15 wt.% of P, not more than 0.02 wt.% of S, 0.01-0.10 wt.% of Al, not more than 0.008 wt.% of N, 0.035-0.20 wt. % of Ti, 0.001-0.015 wt.% of Nb, the contents of the C, S, N, Ti and Nb satisfying the relation of 1.2 (C/12+N/14+S/32) < (Ti/48+Nb/93), and the balance consisting of Fe and unavoidable impurities at a temperature in a range from not lower than the Ar3 transformation point to not higher than 950 ~C and at a draft of not less than 85 %; finish hot-rolling the sheet, while lubricating the same, at a temperature in a range from not lower than 600 ~C to not higher than the Ar3 transformation point at a draft of not less than 65 % so that the average shearing strain ...

HIGH STRENGTH COLD ROLLED STEEL SHEET HAVING EXCELLENT NON-AGING PROPERTY AT ROOM TEMPERATURE AND SUITABLE FOR DRAWING AND METHOD OF PRODUCING THE SAMEN

HIGH TENSILE HOT-ROLLED STEEL SHEET HAVING EXCELLENT STRAIN AGING HARDENING PROPERTIES AND METHOD FOR PRODUCING THE SAME

A high tensile hot-rolled steel sheet which has a chemical composition, in mass %, wherein C: 0.15 % or less, Si: 2.0 % or less, Mn: 3.0 % or less, P: 0.08 % or less, S: 0.02 % or less, Al: 0.02 % or less and N: 0.0050 to 0.0250 %, and optionally more than 0.02 % and not more than 0.1 % of Nb and/or more than 0.02 % and not more than 0.1 % of V are contained in a total amount of 0.1 % or less and wherein N (mass %)/Al (mass %) is 0.3 or more, and which has a tensile strength of 440 Mpa or more and exhibits a BH of 80 Mpa or more and a ΔTS of 40 Mpa or more. The steel sheet is produced by a method which comprises heating a slab having the above composition to a temperature of 1000°C or higher, followed by rough rolling, to provide a sheet bar, subjecting the sheet bar to a finish rolling under a condition wherein an output temperature is 800°C or higher, cooling the resultant product within 0.5 sec after the finish rolling at a cooling rate of 20°C to 40°C/s or more, and reeling it at a ...

HOCHFESTE FEUERVERZINKTE STAHLPLATTE MIT HERVORRAGENDEN PLATTIERUNGSEIGENSCHAFTEN UND HERSTELLUNGSVERFAHREN

PRODUCTION OF A BASE STEEL SHEET TO BE SURFACE- TREATED WHICH IS TO PRODUCE NO STRETCHER STRAIN

Disclosed herein is a method of manufacturing a base steel sheet, which method comprises combined steps of: not rolling a steel slab containing not more than 0.0070% by weight of C (hereinafter referred to breifly as "%"), not more than 0.1% of Si, not more than 0.5% of Mn, 0.010 to 0.080% of Al, not more than 0.0050% of N, not more than 0.030% of S provided that the ratio of Mn/S is not less than 10, and not more than 0.030% of P while the hot rolling being terminated at a finish temperature of not less than 800.degree.C; cold rolling thus obtained hot rolled steel sheet in an ordinary manner; continuously annealing the cold rolled steel sheet in which heating is done up to a temperature from a recrystallization temperature to 800.degree.C, followed by cooling; and then temper rolling the annealing steel sheet at a reduction of not less than 7% by using two or more stand rolling mill, whereby the thus obtained base sheet, to be surface-treated may be utilized for a tinplate or a tin free ...

HIGH-STRENGTH STEEL SHEET FOR FORMING AND PRODUCTION THEREOF

This invention provides a high-strength steel sheet having a small plane anisotropy, a low yield ratio, a complete non-aging property and a high r-value and hardly causing the softening in high temperature heating which is obtained by heating a slab of steel having a composition by weight of C: 0.01-0.1%, Si: 0.1-1.2%, Mn: not more than 3.0%, Ti: value of (Ti%-1.5S%-3.43N%)/C% of 4-12, B: 0.0005-0.005%, Al: not more than 0.1%, P: not more than 0.1%, S: not more than 0.02% and N: not more than 0.05% at a temperature of 1100-1280.degree.C and hot rolling and if necessary cold rolling - annealing.

COLD ROLLED STEEL SHEET EXHIBITING EXCELLENT PRESS WORKABILITY AND METHOD OF MANUFACTURING THE SAME

The invention relates to a cold rolled steel sheet having excellent press workability and a method for making the same. The composition of the cold rolled steel sheet includes 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, while the content of titanium, carbon, sulfur and nitrogen satisfy equation: about 4x(carbon weight percent) percent) - 48/14(nitrogen weight percent) - 48/32(sulfur weight percent) steel sheet may further contain about ...

HOT ROLLED STEEL SHEET AND ITS PRODUCTION PROCESS

After a starting material of steel comprising C: 0.001- 0.20 wt%, Si: 0.01-0.50 wt%, Mn: 0.05-2.0 wt%, P: not more than 0.05 wt%, S: not more than 0.05 wt%, sol.Al: 0.01-0.10 wt%, N: not more than 0.020 wt% and.the balance being Fe and inevitable impurities is heated above Ac3 point, rough rolling is completed within a temperature range of (Ar3 point + 100.degree.C) - (Ar3 point + 50.degree.C), and super-high pressure descaling is carried out under conditions satisfying a jetting pressure of not less than 25 kgf/cm2 and a liquid quantity density of not less than 0.002 liter/cm2, and subsequently finish rolling at a rolling reduction of not less than 80% above Ar3 point of a rolling completion temperature is started in 5 seconds and coiling is carried out below 700.degree.C, whereby hot rolled steel sheets having a surface roughness Ra of not more than 0.8 .mu.m and an average scale thickness of not more than 4 .mu.m is produced and the adhesion property in case of subjecting to shaping ...

Method of manufacturing electric resistance welding pipes having excellent characterization of welded seams

Novel imidazole derivatives

HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLING IN DEEP DRAWABILITY AND METHOD OF PRODUCING THE SAME

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 ~ Nb/C ~ 30, 10 ~ Al/N ~ 80, and 16 ~ (3 x Si/28 + 200 x P/31)/(Mn/55) ~ 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 Ar3 transformation temperature and not lower than 500°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 to 950°C.

Thick cold rolled steel sheet excellent in deep drawability and method of mfg. same

METHOD OF PRODUCING SEAM-WELDED PIPE HAVING GOOD WELDED PORTION CHARACTERISTICS

A method of producing a seam-welded pipe having good welded portion characteristics with high efficiency which positively forms the shape of the opposite ends of the rounded width of a band material immediately before seam-welded into a desired tapered shape in response to a change in band material thickness flexibly to thereby retain a good weld quality. The method of producing a seam-welded pipe which molds a band material (20) and seam-welds it with its ends butt-joined to form a pipe (30), wherein a tapered shape is imparted, before the molding, to the above end on any one surface side of the upper and lower surfaces of the band material and to the facing end by means of cutting or grinding (3) or fin pass rolling (4). © KIPO & WIPO 2008 ...

TUBE WITH HIGH DIMENSIONAL ACCURACY, AND METHOD AND DEVICE FOR MANUFACTURING THE TUBE

A tube with a high dimensional accuracy manufacturable at low cost and having sufficient fatigue strength throughout the wide range of size requirement of the tube and a method of manufacturing the tube. With a plug (1) inserted into a metal tube (5), the metal tube (5) is pushed and passed through the hole of a die (2) for pushing-out. Thus, the pushed-out tube with the high dimensional accuracy in which one or more of an outer diameter deviation, inner diameter deviation, and circumferential wall thickness deviation are 3.0% or less can be provided. © KIPO & WIPO 2007 ...

HIGH STRENGTH STEEL SHEET ADAPTED FOR PRESS FORMING AND METHOD OF PRODUCING THE SAME

A high strength steel sheet adapted for press forming and method producing the same. The steel sheet containing by weight C: 0.01-0.1%, Si: 0.1-1.2%; Mn: not more than 3.0%, Ti:a value of (Ti%-1.5S%-3.43N%)/C% being 4-12, B: 0.0005-0.005%, Al: not more than 0.1%, P: not more than 0.1%, S: not more than 0.02%, N: not more than 0.05%. The method for producing the steel sheet wherein a steel slab containing the above mentioned component composition is heated and hot rolled in a temperature range of 1100-1280.degree.C to provide a hot rolled sheet. The hot rolled sheet may be is subjected to cold rolling and annealing to provide a cold rolled sheet.

HIGH STRENGTH THIN STEEL SHEET, HIGH STRENGTH GALVANNEALED STEEL SHEET AND MANUFACTURING METHOD THEREOF

There is described a manufacturing method for producing a high strength thin steel sheet excellent in workability and galvanizability, comprising the steps of hot-rolling a slab having a composition comprising: C: from 0.01 to 0.20 wt.%, Si: up to 1.0 wt.%, Mn: from 1.0 to 3.0 wt.%, P: up to 0.10 wt.%, S: up to 0.05 wt.%, Al: up to 0.10 wt.%, N: up to 0.010 wt.%, Cr: up to 1.0 wt.%, Mo: from 0.001 to 1.00 wt.%, and optionally one or more elements selected from the group consisting of up to 1.0 wt.% Nb, up to 1.0 wt.% Ti and up to 1.0 wt.% V, with the balance Fe and incidental impurities; coiling the hot-rolled steel sheet at a temperature of up to 750 C, and then, after heating the steel sheet to a temperature of at least 750 .degree.C, cooling the same.

Hochfestes, kaltgewalztes, bei Raumtemperatur alterungsbeständiges, tiefziehbares Stahlblech und Herstellungsverfahren

Hochfestes warmgewalztes Stahlblech mit ausgezeichneten Reckalterungseigenschaften und Herstellungsverfahren dafür

HOCHFESTES, HERVORRAGEND BEARBEITBARES KALTGEWALZTES STAHLBLECH MIT HERVORRAGENDER SCHLAGBESTÄNDIGKEIT

Method of manufacturing electric resistance welding pipes having having excellent characterization of welded seams

METHOD OF MANUFACTURING A COLD-ROLLED STEEL SHEET HAVING A GOOD DEEP DRAWABILITY

60-116,661 Abstract of the Disclosure A method of manufacturing a cold-rolled steel sheet having a good deep drawability is disclosed, wherein a hot rolled steel sheet having a composition of C<0.0035%, Si<1.0%, Mn<1.0%, A?:0.005-0.10%, P<0.15%, N<0.0035%, S<0.015%, Ti:(?N(%)+?S(%)) or {4x(C(%)+N(%))}~(3??C(%)+?N(%)+?S(%)) and Nb: (0.2??C(%))~(?C(%))% is cooled within 2 seconds after the completion of finisher rolling and then at an average cooling rate of not less than 10°C/sec until it arrives at a coiling step, and then the cooled steel sheet is coiled at a temperature of not more than 710°C, subjected to a cold rolling at a reduction of not less than 50%, which was subjected to a continuous annealing in a heatcycle inclusive of heating from 400°C to 600°C at a heating rate of not less than 5°C/sec and soaking at a temperature range of 700°C-Acs point for 1 second or more.

HIGH-TENSILE STRENGTH WELDED STEEL TUBE FOR STRUCTURAL PARTS OF AUTOMOBILES AND METHOD OF PRODUCING THE SAME

The following tube and method are provided: a high-tensile strength welded steel tube having excellent formability and torsional fatigue endurance after being formed into cross-sectional shape and then stress-relief annealed and a method of producing the tube. A steel material used has a composition which contains C, Si, Al, 1.01% to 1.99% Mn, 0.041% to 0.150% Ti, 0.017% to 0.150% Nb, P, S, N, and O such that the sum of the content of Ti and that of Nb is 0.08% or more, the content of each of C, Si, and Al being within an appropriate range, the content of each of P, S, N, and O being adjusted to a predetermined value or less. The steel material is subjected to a hot-rolling step in which the heating temperature and finish-rolling final temperature of the steel material are each within an appropriate range, is slow cooled at a temperature of 650°C to 750°C for 2 s or more, and is then coiled at a temperature of 510°C to 660°C, whereby a hot-rolled steel strip is obtained. The hot-rolled ...

COLD-ROLLED HIGH-TENSION STEEL SHEET HAVING SUPERIOR DEEP DRAWABILITY

A high-tension steel sheet suitable for deep drawing and having superior surface treatment characteristics is made of a steel consisting essentially of, by weight: 0.001 to 0.05 % of C; not more than 1.0 % of Si; not more than 2.5 % of Mn; 0.05 to 1.0 % of Mo; one or both of 0.001 to 0.2 % of Nb and not more than 0.3 % of Ti, wherein Ti* % + (48/93)Nb % ? (48/12)C % in which Ti* % = Ti % - (48/32) S % - (48/14)N %, wherein, when Ti* % < 0, Ti* % is regarded as being 0; 0.0005 to 0.01 % of B; 0.01 to 0.10 % of Al; not more than 0.15 % of P; not more than 0.010 % of S; not more than 0.006 % of N; Si, Mn and P meeting the condition of 0.2 < (Si% + 10P %)/Mn % < 3.3; and the balance substantially Fe and incidental impurities. This steel sheet is produced by a process which includes: hot-rolling the steel slab to obtain a hot rolled steel strip at a final hot-rolling temperature not lower than the Ar3 transformation temperature; coiling the steel strip at a temperature not lower than 300°C but not higher than 615°C when Nb is not contained and not lower than 500°C but not higher than 700°C when Nb is contained; cold-rolling the steel strip to obtain a cold rolled steel strip at a rolling reduction not smaller than 65 %; and recrystallization-annealing the cold rolled strip at a temperature not lower than the recrystallization temperature but below the Ac3 transformation temperature.

METHOD OF MANUFACTURING A COLD ROLLED STEEL SHEET EXHIBITING AN EXCELLENT RESISTANCE TO COLD-WORK EMBRITTLEMENT AND A SMALL PLANAR ANISOTROPY

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°C and 900°C; coiling the material at a temperature lower than 650°C; performing a cold rolling; performing a continuous annealing at a temperature between 830°C and Ac3 transformation point; and performing a skin pass rolling.

COLD-ROLLED THICK SHEET STEEL WITH GOOD DEEP DRAWABILITY, AND METHOD FOR PRODUCING IT

A steel slab having a composition that comprises at most 0.008 % by weight of C, at most 0.5 % by weight of Si, at most 1.0 % by weight of Mn, at most 0.15 % by weight of P, at most 0.02 % by weight of S, from 0.01 to 0.10 % by weight of Al, at most 0.008 % by weight of N, from 0.035 to 0.20 % by weight of Ti, and from 0.001 to 0.015 % by weight of Nb, with a balance of Fe and inevitable impurities, in which those C, S, N, Ti and Nb satisfy the following condition: 1.2(C/12 + N/14 + S/32) < (Ti/48 + Nb/93), is subjected to rough hot-rolling to a reduction ratio of not lower than 85 %, at a temperature falling between the Ar3 transformation point of the steel and 950.degree.C, then to finishing hot-rolling to a reduction ratio of not lower than 65 %, at a temperature falling between 600.degree.C and the Ar3 transformation point of the steel, while being lubricated, to thereby have a mean shear strain of not larger than 0.06, then pickled, pre-annealed at a temperature falling between 700 ...

Hochfestes Stahleinblech zur Umformung durch Pressen und Verfahren zur Herstellung dieser Bleche

HOCHFESTES WARMGEWALZTES STAHLBLECH MIT AUSGEZEICHNETEN RECKALTERUNGSEIGENSCHAFTEN UND HERSTELLUNGSVERFAHREN DAFÜR

NON-AGEING, DEEP DRAWING, CHROMIUM AND TIN PLATE BASE STEEL STRIP

METHOD OF MANUFACTURING A COLD ROLLED STEEL SHEET EXHIBITING AN EXCELLENT RESISTANCE TO COLD WORK EMBRITTLEMENT AND A SMALL PLANAR ANISOTROPY

COLD-ROLLED HIGH-TENSION STEEL SHEET HAVING SUPERIOR DEEP DRAWABILITY

HOT ROLLED STEEL PLATE, COLD ROLLED STEEL PLATE AND HOT DIP GALVANIZED STEEL PLATE BEING EXCELLENT IN STRAIN AGING HARDENING CHARACTERISTICS, AND METHOD FOR THEIR PRODUCTION

A steel plate having a chemical composition in mass %, wherein contents of C, Si and Mn are 0.15 % or less, 2.0 % or less, and 3.0 % or less, respectively, wherein contents of P, S, Al and N are specified, and wherein Cu is contained in an amount of 0.5 to 3.0 %,or at least one of Cr, Mo and W is contained in a total amount of 2.0 % or less, and having a composite structure comprising ferrite as a primary phase and a martensite phase in an area % of 2.0 or more; and a high tensile hot rolled steel plate, a high tensile cold rolled steel plate, and a hot dip galvanized steel plate comprising the steel plate. The steel plate is excellent in press formability, and also has excellent strain aging hardening characteristics wherein ΔTS is 80 Mpa or more. © KIPO & WIPO 2007 ...

High tensile hot-rolled steel sheet having excellent strain aging hardening properties and method for producing the same

A high tensile strength hot-rolled steel sheet having superior strain aging hardenability, which has high formability and stable quality characteristics, and in which satisfactory strength is obtained when the steel sheet is formed into automotive components, thus enabling the reduction in weight of automobile bodies is provided. Specifically, a method for producing a high tensile strength hot-rolled steel sheet having superior strain aging hardenability with a BH of 80 MPa or more, a DeltaTS of 40 MPa or more, and a tensile strength of 440 MPa or more includes the steps of heating a steel slab to 1,000° C. or more, the steel slab containing, in percent by mass 0.15% or less of C, 2.0% or less of Si, 3.0% or less of Mn, 0.08% or less of P, 0.02% or less of S, 0.02% or less of Al, 0.0050% to 0.0250% of N, and optionally 0.1% or less in total of at least one of more than 0.02% to 0.1% of Nb and more than 0.02% to 0.1% of V, the ratio N (mass %)/Al (mass %) being 0.3 or more, rough-rolling ...

Hochfestes Stahleinblech zur Umformung durch Pressen und Verfahren zur Herstellung dieser Bleche

STAHLBLECHE MIT SEHR NIEDRIGEM KOHLENSTOFFGEHALT.

Hot-dip galvanized steel sheet having high strength and also being excellent in formability and galvanizing property

Cold-rolled steel sheet having ultrafine grain structure and method for manufacturing the same

Hot rolled steel plate, cold rolled steel plate and hot dip galvanized steel plate being excellent in strain aging hardening characteristics, and method for their production

High strength steel sheet adapted for press forming and method of producing the same

Hot-dip galvanized steel sheet having high strength and also being excellent in formability and gelvanizing property and method for producing the same

KOMPOSITSTRUKTUR-STAHLPLATTE MIT HOHER ZUGFESTIGKEIT, BESCHICHTETE KOMPOSITSTRUKTUR-STAHLPLATTE MIT HOHER ZUGFESTIGKEIT UND DEREN HERSTELLUNGSVERFAHREN

High-ductility steel sheet excellent in press formability and strain age hardenability, and method for manufacturing the same

Verfahren zum Herstellen leicht verformbarer, hochfester, kaltgewalzter Stahlbleche mit guter Beständigkeit gegen Versprödung durch Weiterbearbeitung

EMBRITTLEMENT RESISTANT ULTRA DEEP DRAWING STEEL

HOCHFESTE HEISSTAUCHZINKBESCHICHTETE STAHLPLATTE MIT HERVORRAGENDEN DUKTILITÄTSEIGENSCHAFTEN UND VERFAHREN ZU DEREN HERSTELLUNG

NON-AGEING, DEEP DRAWING, CHROMIUM AND TIN PLATE BASE STEEL STRIP

HIGH STRENGTH HOT-ROLLED STEEL PLATE

A high strength hot-rolled steel plate, which has a chemical composition, in mass % : C: 0.04 to 0.15 %, Si: 1.5 % or less, Mn: 0.5 to 1.6 %, P: 0.04 % or less, S: 0.005 % or less, Al: 0.04 % or less, Ti: 0. 03 to 0.15 %, Mo: 0.03 to 0.5 %, and the balance: Fe and inevitable impurities, and has a structure which comprises a ferrite containing precipitates, a second phase comprising bainite and/or martensite and another phase except these phases, wherein the proportion of the ferrite containing precipitates is 40 to 95 % and the proportion of the another phase is 5 % or less. The high strength hot-rolled steel plate having a plate thickness of 1.4 mm exhibits a tensile strength of 780 MPa or greater, an elongation of 22 % or more and a bore enlarging ratio of 60 % or more, and thus can be suitably used for a reinforcing member of a cabin of an automobile and for a member resistant to collision. © KIPO & WIPO 2007 ...

Hot-dip galvanized steel sheet having high strength and also being excellent in formability and galvanizing property

HIGH TENSILE HOT-DIP ZINC-COATED STEEL PLATE EXCELLENT IN DUCTILITY AND METHOD FOR PRODUCTION THEREOF

A steel plate having a composition in mass %: C: 0.05 to 0.20 %, Si: 0.3 to 1.8 %, Mn: 1.0 to 3.0 % and balance: Fe and inevitable impurities is subjected to a primary step comprising a primary heat treating and then quenching to a temperature of the M s point thereof or lower, a secondary step comprising a secondary heat treating and then quenching and a third step comprising hot-dip zinc plating and then quenching, to thereby a hot-dip zinc-coated steel plate comprising a steel plate having a composite structure comprising 20 vol % or more of tempered martensite, 2 vol % or more of retained austenite or ferrite and a low temperature transformation phase and, formed thereon, a hot-dip zinc plating layer. The zinc plated steel plate is preferably cooled at a speed of 5 °C/sec or more to 300 °C after plating and may be optionally subjected to an alloying treatment after plating. © KIPO & WIPO 2007 ...

Verfahren zum Herstellen von kaltgewalzten Stahlblechen mit hoher Beständigkeit gegen Versprödung durch Kaltbearbeitung und mit niedriger ebener Anisotropie

High-strength high-workability cold rolled steel sheet having excellent impact resistance

High-ductility steel sheet excellent in press formability and strain age hardenability, and method for manufacturing the same

High-strength high-workability cold rolled steel sheet having excellent im pact resistance

Seamless expandable oil country tubular goods and manufacturing method thereof

The present invention provides a seamless expandable oil country tubular goods, which has a superior pipe expansion property in a expanding process at an expand ratio of more than 30% although having a high strength such as a tensile strength (TS) of 600 MPa or more, and a manufacturing method thereof, the seamless expandable oil country tubular goods being in an as-rolled state or being processed, whenever necessary, by inexpensive nonthermal-refining type heat treatment. In a particular product, 0.010% to less than 0.10% of C, 0.05% to 1% of Si, 0.5% to 4% of Mn, 0.03% or less of P, 0.015% or less of S, 0.01% to 0.06% of Al, 0.007% or less of N, and 0.005% or less of O are contained, and at least one of Nb, Mo, and Cr is contained in the range of 0.01% to 0.2% of Nb, 0.05% to 0.5% of Mo, and 0.05% to 1.5% of Cr, so that Mn+0.9xCr+2.6xMo>=2.0 and 4xC-0.3xSi+Mn+1.3xCr+1.5xMo<=4.5 are satisfied. The micro-structure of a steel pipe preferably contains ferrite at a volume fraction of 5% to ...

COMPOSITE STRUCTURE TYPE HIGH TENSILE STRENGTH STEEL PLATE, PLATED PLATE OF COMPOSITE STRUCTURE TYPE HIGH TENSILE STRENGTH STEEL AND METHOD FOR THEIR PRODUCTION

A composite structure type high tensile strength cold-rolled steel plate which has a chemical composition in mass %: C: 0.01 to 0.08 %, Si: 2.0 % or less, Mn: 3.0 % or less, P: 0.10 % or less, S: 0.02 % or less, Al: 0.005 to 0.20 %, N: 0.02 % or less, V: 0.01 to 0.5 % and balance: substantially Fe and inevitable impurities, provided that contents of V and C satisfy the relationship: 0.5 x C/12 <= V/51 <= 3 x C/12, and has a structure comprising a ferrite phase as a primary phase and a second phase containing a martensite phase in an amount of 1 area % or more relative to the total structure; a galvanized plate of a composite structure type high tensile strength steel which comprises the above steel plate and a hot dip zinc plating formed thereon; and a method for producing the steel plate. The composite structure type high tensile strength exhibits excellent deep drawability. © KIPO & WIPO 2007 ...

Hot rolled steel plate and cold rolled steel plate being excellent in strain aging hardening characteristics

The present invention provides a steel sheet having a chemical composition comprising 0.15% or less C, 2.0% or less Si, 3.0% or less Mn, P, S, Al and N in adjusted amounts, from 0.5 to 3.0% Cu, or one or more of Cr, Mo and W in a total amount of 2.0% or less, and having a composite structure comprising ferrite and martensite having an area ratio of 2% or more. The steel sheet is in the form of a high-strength hot-rolled steel sheet, a high-strength cold-rolled steel sheet, or a hot-dip galvanized steel sheet. There is thus available a steel sheet excellent in press-formability and in strain age hardening property as represented by a DeltaTS of 80 MPa or more.

HIGH TENSILE COLD-ROLLED STEEL SHEET EXCELLENT IN DUCTILITY AND IN STRAIN AGING HARDENING PROPERTIES, AND METHOD FOR PRODUCING THE SAME

A high tensile cold-rolled steel sheet which has a chemical composition, in mass %, wherein C: 0.05 % to 0.30, Si: 0.4 to 2.0 %, Mn: 0.7 to 3.0 %, P: 0.08 % or less, Al: 0.02 % or less, and N: 0.0050 to 0. 0250 %, and N /Al is 0. 3 or more, and a specific composite structure, and which exhibits excellent ductility and impact resistance and excellent strain aging hardening properties represented by a ΔTS of 50 Mpa or more. The steel sheet is produced by a method which comprises preparing a cold-rolled thin steel sheet having the above composition, heating the cold-rolled thin steel sheet to a temperature between (Ac1 transformation point) and (Ac3 transformation point + 50 °C, and then cooling it at a cooling rate of 5 to 150 °C at least in the range of from 600 °C to 500 °C and holding it in a temperature range of 350 °C to 500 °C. © KIPO & WIPO 2007 ...

METHOD AND SYSTEM FOR SUPPORT SERVICE SUPPORTING INFORMATION TRANSACTION AND COOPERATIVE INVESTMENT AMONG INVESTORS AND RECORDING MEDIUM WITH RECORDED SUPPORTING PROGRAM

PROBLEM TO BE SOLVED: To provide service which eliminates a waste of repetitive investigation and greatly reduce the investigation costs of respective investors and the cost for cooperative investments by supporting information transactions and the cooperative investments among the investors. SOLUTION: This method has a procedure for sending a member list to the terminal of an investor and receiving the specification of a partner for an information transaction or cooperative investment, a procedure for obtaining information conditions of the information transaction, a procedure for presenting information regarding the information transaction or cooperative investment to the specified member investor, a procedure for managing contract conclusion between an inviting investor who agrees and a candidate investor, a procedure for obtaining and storing detailed information regarding investment matters from the terminal of an organizing investor, and a procedure for transmitting the detailed information ...

Hollow member and method for manufacturing same

A method for manufacturing a hollow member excellent in durability is provided. Specifically, a seam-welded steel pipe made of a steel sheet and having a low-carbon layer width 2h is subjected to quenching in a way that the pipe is heated to a heating temperature T(K) over the Ac3 transformation point at a heating rate Vh(K/s), in no time cooled to a quenching start temperature Tq(K) at a primarycooling rate Vc(K/s), and secondarily cooled (quenched). The heating rate Vh, the highest heating temperature T, and the primary cooling rate Vc are regulated so that formula (1) below may be satisfied (in the formula, Co (mass%): the content (mass%) of C in the steel sheet), t: the diffusion time (s), t=50/Vh+50/Vc+k, Vh: heating rate (K/s), Vc: the primary cooling rate (K/s), k: the soaking time (s), D: the diffusion coefficient (m2/s), D=Doexp(-Q/RT), Do: 4.7OE0-5 (m2/s), Q=155 (kJ/mol K), R=8.31 (J/mol K), T: the highest heating temperature (K)). The quenching start temperature Tq is overthe ...

HOT-DIP GALVANIZED STEEL SHEET HAVING HIGH STRENGTH AND ALSO BEING EXCELLENT IN FORMABILITY AND GALVANIZING PROPERTY

A hot-dip galvanized steel sheet having a high strength and being excellent in formability and galvanizing property, characterized in that the steel has a chemical composition: C: 0.01 to 0.20 wt %, Si: 1.0 wt % or less, Mn: more than 1.5 wt % and 3.0 wt % or less, P: 0.10 wt % or less, S: 0.05 wt % or less, Al: 0.10 wt % or less, N: 0.010 wt % or less, one or more elements selected from among Ti, Nb and V: 0.010 to 1.0 wt % in total, and the balance: Fe and inevitable impurities, and has a metal structure wherein an area percentage of a ferrite phase is 50 % or more, an average grain diameter in the ferrite phase is 10 μm or less and the thickness of a band- shaped structure comprised of a second phase satisfies the relationship: Tb/T <= 0.005 wherein Tb represents an average thickness of the band-shaped structure in the direction of thickness of the sheet; and a method for producing the steel sheet. The galvanized steel sheet can be produced by the use of a continuous hot-dip galvanizing ...

High tensile cold-rolled steel sheet excellent in ductility and in strain aging hardening properties, and method for producing the same

The present invention provides a high tensile cold-rolled steel sheet having superior ductility, strain age-hardening characteristics, and crash resistance properties, and also provides a manufacturing method therefor. As a particular means, a thin cold-rolled steel sheet containing 0.05% to 0.30% of C, 0.4% to 2.0% of Si, 0.7% to 3.0% of Mn, 0.08% or less of P, 0.02% or less of Al, and 0.0050% to 0.0250% of N on a mass % basis is manufactured in which N/Al is 0.3 or more. This thin cold-rolled steel sheet is heated to a temperature between (an Ac1 transformation point) and (an Ac3 transformation point+50° C.), is cooled at a cooling rate of 5 to 150° C./second in the range of at least 600 to 500° C., and is held in the temperature range of 350 to 500° C. This steel sheet has superior ductility, strain age-hardening characteristics having a DeltaTS of 50 MPa or more, and crash resistance properties.

METHOD FOR ELECTRIC RESISTANCE WELDED STEEL TUBE

A method for manufacturing an electric resistance welded steel tube including: forming a steel tube material into an almost cylindrical open pipe, the steel tube material being a steel sheet wherein Ti and N satisfy (N/14)<(Ti/47.9); forming an electric resistance welded steel tube by bonding ends of the open pipe to each other by induction resistance welding with heat input controlled so that the bond width is 30 to 65 μm; heating the electric resistance welded steel tube to a temperature equal to or higher than the Actransformation temperature; and diameter-reducing rolling the heated electric resistance welded steel tube with rolling reduction expressed by an outer diameter ratio greater than (1-25/the bond width before diameter-reducing rolling (μm))×100% such that the bond width is 25 μm or less. 2. The method according to claim 1 , wherein the composition further comprises one or more selected from claim 1 , in mass percent claim 1 , Cr: 1.0% or less claim 1 , Mo: 1.0% or less claim 1 , W: 1.0% or less claim 1 , Ni: 1.0% or less claim 1 , and Cu: 1.0% or less.3. The method according to claim 1 , wherein the composition further contains either or both of claim 1 , in mass percent claim 1 , Nb: 0.2% or less and V: 0.2% or less.4. The method according to claim 2 , wherein the composition further contains either or both of claim 2 , in mass percent claim 2 , Nb: 0.2% or less and V: 0.2% or less. This is divisional application of 12/528,551 filed Aug. 25, 2009, which is a §371 of International Application No. PCT/JP2008/051596, with an international filing date of Jan. 25, 2008 (WO 2008/105216 Al, published Sep. 4, 2008), which is based on Japanese Patent Application No. 2007-045749, filed Feb. 26, 2007, the subject matter of which is incorporated by reference.This disclosure relates to an electric resistance welded steel tube suitably used for applications exposed to quenching treatment such as hollow stabilizers and, in particular, to improvement in hardenability ...

High strength cold rolled steel sheet having excellent non-agin property at room temperature and suitable for drawing and method of producing the same

The invention in its first aspect provides a high strength cold rolled steel sheet having excellent non-aging property at room temperature and excellent drawability, said steel sheet having a dual-phase structure composed of a high-temperature transformed ferrite phase and a low-temperature transformed ferrite phase having high dislocation density, said steel sheet having a composition which essentially contains: not less than 0.001 wt% but not more than 0.025 wt% of C, not more than 1.0 wt% of Si, not less than 0.1 wt% but not more than 2.0 wt% of Mn, not less than 0.001 wt% but not more than 0.2 wt% of Nb, not less than 0.0003 wt% but not more than 0.01 wt% of B, not less than 0.005 wt% but not more than 0.10 wt% of Al, not more than 0.1 wt% of P, not more than 0.007 wt% of N, at least one selected from a group consisting of not less than 0.05 wt% but not more that 3.0 wt% of Ni, not less than 0.01 wt% but not more than 2.0 wt% of Mo and not less than 0.05 wt% but not more than 5.0 wt% of Cu, and the balance being substantially Fe with inevitable impurities. This steel sheet is produced by preparing a hot-rolled steel sheet having the above-specified composition, cold rolling the hot-rolled steel sheet at a rolling reduction not smaller than 60 %, annealing the cold rolled steel sheet at a temperature which is not lower than the γ transformation start temperatures but below the A c3 transformation temperature, and cooling the annealed steel sheet at a rate not smaller than 5°C/sec but not greater than 100°C/sec. The invention in its second aspect provides a high strength cold rolled steel sheet having excellent non-aging property at room temperature and bake hardenability, as well as excellent drawability, said steel sheet exhibiting a tensile strength not smaller than 45 Kgf/mm² and having a dual-phase structure composed of a high-temperature transformed ferrite phase and a low-temperature transformed ferrite phase having high dislocation density, said steel ...

Thin steel plate of high rectangular tube drawability and method of manufacturing the same

A thin steel plate of a high rectangular tube drawability obtained by finishing rough rolling of steel - which containing not more than 0.02 wt.% of C, not more than 0.5 wt.% of Si, not more than 1.0 wt.% of Mn, not more than 0.15 wt.% of P, not more than 0.02 wt.% of S, 0.091-0.10 wt.% of Al, not more than 0.008 wt.% of N, one or two kinds of 0.001-0.20 wt.% of Ti and 0.001-0.15 wt.% of Nb, and the balance including Fe and unavoidable impurities - in a temperature region of 950 °C to Ar3 transformation point, finish-rolling the rough-rolled plate while lubricating the same in a temperature region of the Ar3 transformation point to 500 °C at a draft of over 70 %, pickling the resultant mother plate, annealing the mother plate under conditions satisfying the following relations: (T+273)(20+log t)≥2.50x104 (I) and 745≤T≤920 (2) where T represents the mother plate annealing temperature (°C); and t parent the plate annealing time (sec), and thereafter cold-rolling this mother plate at a draft of 50-95 %, i.e., recrystallization-annealing the same. The resultant thin steel plate satisfying the relations (r¿L? + rC)/2-rD≥0,67 and (rL + 2rD + rC)/4≥2.7, where rL represents the Lankford value in the rolling direction; rD the Lankford value in the direction at an angle of 45° with respect to the rolling direction; and rC the value in the direction perpendicular to the rolling direction.

Steel for structural part of automobile and method for producing the same

The present invention provides a steel having excellent formability, fatigue endurance after quenching, low temperature toughness, resistance for hydrogen embrittlement, and corrosion fatigue endurance. Resolving means includes heating a steel slab at 1160°C to 1320°C, hot-finish-rolling the steel slab at a finisher delivery temperature of 750°C to 980°C, and then coiling the hot-rolled steel at a coiling temperature of 560°C to 740°C after slow cooling for a time of 2 seconds or more to produce a hot-rolled steel strip having a structure in which the ferrite grain diameter df corresponding to a circle is 1.1 m, to less than 1.2 µm and the ferrite volume fraction Vf is 30% to 98%, the steel slab containing 0.18 to 0.29% of C, 0.06 to 0.45% of Si, 0.91 to 1.85% of Mn, 0.019% or less of P, 0.0029% or less of S, 0.015 to 0.075% of sol. Al, 0.0049% or less of N, 0.0049% or less of 0, 0.0001 to 0.0029% of B, 0.001 to 0.019% of Nb, 0.001 to 0.029% of Ti, 0.001 to 0.195% of Cr, and 0.001 to 0.195% of Mo so that the carbon equivalent Ceq satisfies a value of 0.4 to less than 0.58, and the total x of multiplying factors including that for B according to Grossmann satisfies a value of 1.2 to less than 1.7. The hot-rolled steel strip is used as a raw material for producing a steel tube by electric resistance welded tube making with a width reduction of hoop of 8% or less.

Hot-dip galvanized high-strength steel sheet having superior workability and galvanizability and method for producing the same

A hot-dip galvanized high-strength steel sheet having superior workability and galvanizability containing: 0.01% to 0.20% by weight of C; 1.0% by weight or less of Si; more than 1.5% to 3.0% by weight of Mn; 0.10% by weight or less of P; 0.05% by weight or less of S; 0.10% by weight or less of Al; 0.010% by weight or less of N; 0.010% to 1.0% by weight in total of at least one element selected from the group consisting of Ti, Nb, and V; and the balance being Fe and incidental impurities; in which the steel sheet has the metal structure in which the areal rate of the ferrite phase is 50% or more, the ferrite phase has an average grain diameter of 10 µm or less, and the thickness of a band-like structure composed of the second phase satisfies the relationship Tb/T <= 0.005, where Tb is the average thickness in the sheet thickness direction of the band-like structure and T is the thickness of the steel sheet, and a method for producing the same. To provide a method for producing a hot-dip galvanized high-strength steel sheet in which superior workability and high strength are obtained and moreover satisfactory galvanizability is obtained when galvanizing is performed using facilities such as a continuous galvanizing line.

Hot-rolled steel sheet, cold-rolled steel sheet and hot-dip galvanized steel sheet excellent in strain age hardening property, and manufacturing method thereof

The present invention provides a steel sheet having a chemical composition comprising 0.15% or less C, 2.0% or less Si, 3.0% or less Mn, P, S, Al and N in adjusted amounts, from 0.5 to 3.0% Cu, or one or more of Cr, Mo and W in a total amount of 2.0% or less, and having a composite structure comprising ferrite and martensite having an area ratio of 2% or more. The steel sheet is in the form of a high-strength hot-rolled steel sheet, a high-strength cold--rolled steel sheet, or a hot-dip galvanized steel sheet. There is thus available a steel sheet excellent in press--formability and in strain age hardening property as represented by a .DELTA.TS of 80 MPa or more.

Composite structure type high tensile strength steel plate, plated plate of composite structure type high tensile strength steel and method for their production

Method for electric resistance welded steel tube

A method for manufacturing an electric resistance welded steel tube including: forming a steel tube material into an almost cylindrical open pipe, the steel tube material being a steel sheet wherein Ti and N satisfy (N/14)<(Ti/47.9); forming an electric resistance welded steel tube by bonding ends of the open pipe to each other by induction resistance welding with heat input controlled so that the bond width is 30 to 65 μm; heating the electric resistance welded steel tube to a temperature equal to or higher than the Ac 3 transformation temperature; and diameter-reducing rolling the heated electric resistance welded steel tube with rolling reduction expressed by an outer diameter ratio greater than (1−25/the bond width before diameter-reducing rolling (μm))×100% such that the bond width is 25 μm or less.

Expansible seamless steel pipe for use in oil well and method for production thereof

An expansible seamless steel pipe for use in oil well, which contains C: 0.010 % or more and less than 0.10 %, Si: 0.05 to 1 %, Mn: 0.5 to 4 %, P: 0.03 % or less, S: 0.015 % or less, Al: 0.01 to 0.06 %, N: 0.007 % or less, O: 0.005 % or less, Nb: 0.01 to 0.2 %, and contains one or more of Nb, Mo and Cr in the range that Nb: 0.01 to 0.2 %, Mo: 0.05 to 0.5 %, and Cr: 0.05 to 1.5 %, with the proviso that the formulae of Mn + 0.9×Cr + 2.6×Mo >= 2.0 and 4×C - 0.3×Si + Mn + 1.3×Cr + 1.5×Mo <= 4.5 are satisfied; and a method for producing the steel pipe. The pipe preferably has a structure wherein ferrite is contained in 5 to 70 vol % and the balance consists substantially of a low temperature transformation phase. The above pipe is produced by a method comprising one or more of the conditions that (a) the temperature at the completion of rolling in the formation of the pipe is 800~C or higher, (b) the pipe is subjected to a normalizing treatment and (c) the pipe is formed, then is held in a two-phase region for five minutes or longer, and thereafter is air cooled. The above pipe exhibits high strength of a tensile strength (TS) of 600 MPa or more and also excellent expandability to a tube expanding of an expanding ratio exceeding 30 % even when it is subjected, after rolling, to no further treatment or only to a non-refining heat treatment not requiring a high cost.

Thin steel plate of high rectangular tube drawability and method of manufacturing the same

A thin steel sheet having excellent rectangular drawability is produced by completing roughing rolling of steel containing C: 0.02 wt% or less, Si: 0.5 wt% or less, Mn: 1.0 wt% or less, P: 0.15 wt% or less, S: 0.02 wt% or less, Al: 0.01 to 0.10 wt%, N: 0.008 wt% or less, at least one of Ti: 0.001 to 0.20 wt% and Nb: 0.001 to 0.15 wt%, the balance comprising Fe, and inevitable impurities, in the temperature region of 950°C to the Ar 3 transformation temperature: performing finish rolling at a reduction of over 70% under lubrication in the temperature region of the Ar 3 transformation temperature to 500°C; pickling the sheet; annealing the resultant hot rolled sheet under conditions which satisfy the equations (1) and (2) below: (T + 273) (20 + log t) ≥ 2.50 x 10 4 745 ≤ T ≤ 920 wherein T: hot rolled sheet annealing temperature (°C) t: hot rolled sheet annealing time (sec); cold rolling at a reduction of 50 to 95%; and then recrystallization annealing; to satisfy the following relations: (r L + r C )/2 - r D ≥ 0.67, and (r L + 2r D + r C )/4 ≥ 2.7, wherein r L : Lankford value in the rolling direction, r D : Lankford value in the direction at 45° with the rolling direction, and r C : Lankford value in the direction perpendicular to the rolling direction.

Tube with high dimensional accuracy, and method and device for manufacturing the tube

There are provided a high dimensional accuracy pipe and a manufacturing method thereof, the pipe being in response to wide requirements of sizes, being manufactured at inexpensive cost, and having a sufficient fatigue strength. The detailed structure thereof is as follows. A push-to-pass process is performed in which, while a plug 1 is being charged in a metal pipe 5 , the metal pipe is pushed in a hole provided in a die 2 and is then allowed to pass therethrough. As a result, a high dimensional accuracy pipe can be obtained in which at least one of the deviation of the outer diameter, the deviation of the inner diameter, and the deviation of the thickness in the circumferential direction is 3.0% or less as processed.

High-strength cold-rolled steel sheet excelling in deep drawability and method of producing the same

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≦Nb/C≦30, 10≦Al/N≦80, and 16≦(3×Si/28+200 ×P/31)/(Mn/55)≦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 3 transformation temperature and not lower than 500° 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 ° to 950° C.

High dimensional accuracy pipe, manufacturing method thereof, and manufacturing apparatus

A tube with a high dimensional accuracy manufacturable at low cost and having sufficient fatigue strength throughout the wide range of size requirement of the tube and a method of manufacturing the tube. With a plug (1) inserted into a metal tube (5), the metal tube (5) is pushed and passed through the hole of a die (2) for pushing-out. Thus, the pushed-out tube with the high dimensional accuracy in which one or more of an outer diameter deviation, inner diameter deviation, and circumferential wall thickness deviation are 3.0% or less can be provided.

High-ductility steel sheet excellent in press formability and strain age hardenability, and method for manufacturing the same

A steel sheet composition contains appropriate amounts of C, Si, Mn, P, S, Al and N and 0.5 to 3.0% Cu. A composite structure of the steel sheet has a ferrite phase or a ferrite phase and a tempered martensite phase as a primary phase, and a secondary phase containing retained austenite in a volume ratio of not less than 1%. In place of the Cu, at least one of Mo, Cr, and W may be contained in a total amount of not more than 2.0%. This composition is useful in production of a high-ductility hot-rolled steel sheet, a high-ductility cold-rolled steel sheet and a high-ductility hot-dip galvanized steel sheet having excellent press formability and excellent stain age hardenability as represented by a ΔTS of not less than 80 MPa, in which the tensile strength increases remarkably through a heat treatment at a relatively low temperature after press forming.

Process for producing a hot-rollled steel sheet

Process for producing high tensile hot-dip zinc-coated steel sheet of excellent ductility and antifatigue properties

A hot rolled plate of a composition comprising 0.05 to 0.20 mass% of C, 0.3 to 1.8 mass% of Si, 1.0 to 3.0 mass% of Mn and the remainder consisting of Fe a nd inevitable impurities, having a composite texture consisting of ferrite main phase and second phase wherein the second phase comprises 80 vol.% or more o f bainite and the remainder consisting of any one or two or more of martensite , retained austenite and pearlite and wherein the ratio of plate-thickness- direction average length to average length of the second phase is 0.7 or mor e, as a starting material, is subjected to cold rolling, given heat treatment, hot dip zinc coating and cooling operations. As a result, there can be obtained a high tensile hot-dip zinc-coated steel sheet exhibiting a ductili ty that is satisfactory for use as a material of automobile parts and also excellent antifatigue properties.

Steel product for structural member of automobile and method for production thereof

A method for producing a steel product which comprises providing a steel slab having a chemical composition satisfying C: 0.18 to 0.29 %, Si: 0.06 to 0.45 %, Mn: 0.91 to 1.85 %, P: 0.019 % or less, S: 0.0029% or less, sol.Al: 0.015 to 0.075%, N: 0.0049 % or less, O: 0.0049 % or less, B: 0.0001 to 0.0029 %, Nb: 0.001 to 0.019 %, Ti: 0.001 to 0.029 %, Cr: 0.001 to 0.195 %, Mo: 0.001 to 0.195 %, and 0.4 or more and less than 0.58 of Ceq, and satisfying that the sum (χ) of hardenability multiples according to Grossmann being aware of B is 1.2 or more and less than 1.7, heating the steel slab to 1160 to 1320˚C, subjecting the resultant slab to a hot finish rolling having an ending temperature for the finish rolling of 750 to 980˚C, annealing the rolled product for a period of 2s or more before winding, and then winding the product up at a temperature of 560 to 740˚C, to thereby produce a hot-rolled steel belt which has a structure having an average grain diameter (df) corresponding to a ferrite circle of 1.1 μm or more and less than 12 μm and a ferrite volume percentage (Vf) of 30 to 98 %. A steel pipe is produced by a method comprising using the above hot-rolled steel belt as a material and subjecting it to an electric welding wherein a reduction ratio for width is 8 % or less. A steel product produced by the above method is excellent in formability, fatigue strength after hardening, toughness at a low temperature, characteristics of resistance to delayed break and corrosion fatigue strength.

Hollow member and method for manufacturing same

A method for manufacturing a hollow article having excellent durability is provided. In particular, an electric resistance welded steel pipe which is made from a steel sheet and in which the width of a low carbon layer is 2h (m) is subjected to a heat treatment that includes a quenching treatment in which the electric resistance welded steel pipe is heated to a heating temperature T (K) not lower than the Ac 3 transformation temperature at a heating rate V h (K/s), held for a soaking time k (s), immediately cooled to a quenching start temperature Tq (K) at a primary cooling rate V c (K/s), and then secondarily cooled (quenched). The heating rate V h , the maximum heating temperature T, and the primary cooling rate V c are adjusted so as to satisfy an inequality (herein C 0 (mass percent) is the C content (mass percent) of the steel sheet, t is the diffusion time (s), t = 50 / V h + 50 / V c + k, V h is the heating rate (K/s), V c is the primary cooling rate (K/s), k is the soaking time (s), D is the diffusion coefficient (m 2 /s), D (m 2 /s) = D 0 exp(-Q / RT), Do is 4.7 × 10 -5 (m 2 /s), Q = 155 (kJ/mol·K), R = 8.31 (J/mol·K), and T is the maximum heating temperature (K)) and the quenching start temperature Tq is higher than the Ar 3 transformation temperature. This prevents the hardness as quenching of the electric resistance welded portion from being reduced and significantly increases the durability of the heat-treated article. 0.83 ‰¤ 1 - 1 - 0.09 / C 0 ˆ« - h h exp - y 2 / 4 ¢ Dt / 4 ¢ ÀDt ¢ dy

Apparatus and method for sealing paper with paste

An apparatus for sealing paper with paste includes a paper-feeding unit, a pasting main body which seals open ends of a sheet of paper by an adhesive, and a paper-receiving unit on which the sealed sheets of paper are loaded. The pasting main body includes an opening mechanism which opens a closed sheet of paper, an adhesive applying mechanism which applies a peelable temporary adhesive in a streaky form to a lower folded piece of the opened sheet of paper, a sealing mechanism which superposes an upper folded piece on the lower folded piece, and which temporarily adheres the open ends of the upper and lower folded pieces, and a conveying mechanism.

Production of a base steel sheet to be surface-treated which is to produce no stretcher strain

High tensile hot rolled steel sheet excellent in shape freezing property and endurance fatigue characteristics after forming

Production of a base steel sheet to be surface-treated which is to produce no stretcher strain

METHOD FOR PRODUCING HOT-ROLLED STEEL SHEET

Composite structure type high tensile strength steel plate, plated plate of composite structure type high tensile strength steel and method for their production

The invention proposes a high-strength dual-phase cold rolled steel sheet having an excellent deep drawability, wherein the steel sheet has a composition comprising C: 0.01-0.08 mass%, Si: not more than 2.0 mass%, Mn: not more than 3.0 mass%, P: not more than 0.10 mass%, S: not more than 0.02 mass%, Al: 0.005-0.20 mass%, N: not more than 0.02 mass% and V: 0.01-0.5 mass%, provided that V and C satisfy a relationship of 0.5×C/12 ≤ V/51 ≤ 3×C/12, and the remainder being Fe and inevitable impurities, and has a microstructure consisting of a ferrite phase as a primary phase and a secondary phase including martensite phase at an area ratio of not less than 1% to a whole of the microstructure and a high-strength dual-phase galvanized steel sheet comprising a galvanized coating on the above steel sheet as well as a method of producing the same.

Methods of manufacturing hot-dip galvanized hot-rolled and cold-rolled steel sheets excellent in strain age hardening property

The present invention provides a steel sheet having a chemical composition comprising 0.15% or less C, 2.0% or less Si, 3.0% or less Mn, P, S, Al and N in adjusted amounts, from 0.5 to 3.0% Cu, or one or more of Cr, Mo and W in a total amount of 2.0% or less, and having a composite structure comprising ferrite and martensite having an area ratio of 2% or more. The steel sheet is in the form of a high-strength hot-rolled steel sheet, a high-strength cold-rolled steel sheet, or a hot-dip galvanized steel sheet. There is thus available a steel sheet excellent in press-formability and in strain age hardening property as represented by a ΔTS of 80 MPa or more.

Thick cold rolled steel sheet excellent in deep drawability and method of manufacturing the same

A thick cold rolled steel sheet having an r value of not less than 2.9 even when the thickness is not less than 1.2 mm; and a method of manufacturing the same, comprising: rough hot-rolling a steel slab which contains not more than 0.008 wt.% of C, not more than 0.5 wt.% of Si, not more than 1.0 wt.% of Mn, not more than 0.15 wt.% of P, not more than 0.02 wt.% of S, 0.01-0.10 wt.% of Al, not more than 0.008 wt.% of N, 0.035-0.20 wt. % of Ti, 0.001-0.015 wt.% of Nb, the contents of the C, S, N, Ti and Nb satisfying the relation of 1.2 (C/12+N/14+S/32) < (Ti/48+Nb/93), and the balance consisting of Fe and unavoidable impurities at a temperature in a range from not lower than the Ar3 transformation point to not higher than 950 °C and at a draft of not less than 85 %; finish hot-rolling the sheet, while lubricating the same, at a temperature in a range from not lower than 600 °C to not higher than the Ar3 transformation point at a draft of not less than 65 % so that the average shearing strain may be not more than 0.06; pickling the steel sheet; subjecting the sheet to mother plate annealing at 700 to 920 °C; cold rolling the sheet at a draft of not less than 65 %; and annealing the sheet steel for recrystallization at 700 °-920 °C.

High tensile hot-rolled steel sheet having excellent strain aging hardening properties and method for producing the same

The present invention provides a high tensile strength hot-rolled steel sheet having superior strain aging hardenability, which has high formability and stable quality characteristics, and in which satisfactory strength is obtained when the steel sheet is formed into automotive components, thus enabling the reduction in weight of automobile bodies. Specifically, a method for producing a high tensile strength hot-rolled steel sheet having superior strain aging hardenability with a BH of 80 MPa or more, a .DELTA.TS of 40 MPa or more, and a tensile strength of 440 MPa or more includes the steps of heating a steel slab to 1,000°C or more, the steel slab containing, in percent by mass, 0.15% or less of C, 2.0% or less of Si, 3.0% or less of Mn, 0.08% or less of P, 0.02% or less of S, 0.02% or less of Al, 0.0050% to 0.0250% of N, and optionally 0.1% or less in total of at least one of more than 0.02% to 0.1% of Nb and more than 0.02% to 0.1% of V, the ratio N (mass%)/Al (mass%) being 0.3 or more; rough-rolling the steel slab to form a sheet bar; finish-rolling the sheet bar at a finishing temperature of 800°C or more; cooling at a cooling rate of 20°C to 40°C/s or more within 0.5 second after the finish-rolling; and coiling at a temperature of 650°C to 450°C or less.

High tensile strength hot-rolled steel sheet having superior strain aging hardenability and method for producing the same

A high tensile strength hot-rolled steel sheet having superior strain aging hardenability, which has high formability and stable quality characteristics, and in which satisfactory strength is obtained when the steel sheet is formed into automotive components, thus enabling the reduction in weight of automobile bodies. Specifically, a method for producing a high tensile strength hot-rolled steel sheet having superior strain aging hardenability with a BH of 80 MPa or more, a ΔTS of 40 MPa or more, and a tensile strength of 440 MPa or more includes the steps of heating a steel slab to 1,000° C. or more, the steel slab containing, in percent by mass, 0.15% or less of C, 0.45% or less of Si, 3.0% or less of Mn, 0.08% or less of P, 0.02% or less of S, 0.02% or less of Al, 0.0050% to 0.0250% of N, and optionally 0.1% or less in total of at least one of more than 0.02% to 0.1% of Nb and more than 0.02% to 0.1% of V, the ratio N (mass %)/Al (mass %) being 0.86 or more; rough-rolling the steel slab to form a sheet bar; finish-rolling the sheet bar at a finishing temperature of 800° C. or more; cooling at a cooling rate of 20° C. to 40° C./s or more within 0.5 second after the finish-rolling; and coiling at a temperature of 650° C. to 450° C. or less.

Method of manufacturing a cold-rolled steel sheet having a good deep drawability

A method of manufacturing a cold-rolled steel sheet having a good deep drawability is disclosed, wherein a hot rolled steel sheet having a composition of C≦0.0035%, Si≦1.0%, Mn≦1.0%, Al:0.005-0.10%, P≦0.15%, N≦0.0035%, S≦0.015%, Ti: (48/14N(%)+48/32S(%)) or {4×(C(%)+N(%))}˜(3.48/12C(%)+48/14N(%)+48/32S(%)) and Nb: (0.2.93/12C(%))˜(93/12C(%))% is cooled within 2 seconds after the completion of finisher rolling and then at an average cooling rate of not less than 10° C./sec until it arrives at a coiling step, and then the cooled steel sheet is coiled at a temperature of not more than 710° C., subjected to a cold rolling at a reduction of not less than 50%, which was subjected to a continuous annealing in a heatcycle inclusive of heating from 400° C. to 600° C. at a heating rate of not less than 5° C./sec and soaking at a temperature range of 700° C.-Ac 3 point for 1 second or more.

High tensile hot-rolled steel sheet having excellent strain aging hardening properties and method for producing the same

The present invention provides a high tensile strength hot-rolled steel sheet having superior strain aging hardenability, which has high formability and stable quality characteristics, and in which satisfactory strength is obtained when the steel sheet is formed into automotive components, thus enabling the reduction in weight of automobile bodies. Specifically, a method for producing a high tensile strength hot-rolled steel sheet having superior strain aging hardenability with a BH of 80 MPa or more, a .DELTA.TS of 40 MPa or more, and a tensile strength of 440 MPa or more includes the steps of heating a steel slab to 1,000°C or more, the steel slab containing, in percent by mass, 0.15% or less of C, 2.0% or less of Si, 3.0% or less of Mn, 0.08% or less of P, 0.02% or less of S, 0.02% or less of Al, 0.0050% to 0.0250% of N, and optionally 0.1% or less in total of at least one of more than 0.02% to 0.1% of Nb and more than 0.02% to 0.1% of V, the ratio N (mass%)/Al (mass%) being 0.3 or more; rough-rolling the steel slab to form a sheet bar; finish-rolling the sheet bar at a finishing temperature of 800°C or more; cooling at a cooling rate of 20°C to 40°C/s or more within 0.5 second after the finish-rolling; and coiling at a temperature of 650°C to 450°C or less.

Warm-, kaltgewalzte und schmelz-galvanisierte stahlplatte mit exzellentem reckalterungsverhalten

Hochduktiles stahlblech mit exzellenter pressbarkeit und härtbarkeit durch verformungsalterung sowie verfahren zur dessen herstellung

Thick cold rolled steel sheet excellent in deep drawability and its manufacturing method

mÉtodo para produzir aÇo para chapas grossas laminadas a frio e aÇo para chapas grossas laminadas a frio.

Extra low carbon steel sheets