Entries |
Document | Title | Date |
20090050243 | HIGH STRENGTH HOT ROLLED STEEL SHEET EXCELLENT IN BORE EXPANDING WORKABILITY AND METHOD FOR PRODUCTION THEREOF - A high-strength hot-rolled steel sheet containing C: 0.05 to 0.15%, Si: no more than 1.50% (excluding 0%), Mn: 0.5 to 2.5%, P: no more than 0.035% (excluding 0%), S: no more than 0.01% (including 0%), Al: 0.02 to 0.15%, and Ti: to 0.2%, which is characterized in that its metallographic structure is composed of 60 to 95 vol % of bainite and solid solution-hardened or precipitation-hardened ferrite (or ferrite and martensite) and its fracture appearance transition temperature (vTrs) is no higher than 0° C. as obtained by impact tests. (% in terms of % by weight) | 02-26-2009 |
20090050244 | Hot-Rolled High Strength Steel Sheet Having Excellent Ductility, Stretch-Flangeability, and Tensile Fatigue Properties and Method for Producing the Same - The present invention provides a hot-rolled high strength steel sheet in which, without using expensive Mo, by effectively using Ti which is an inexpensive element and the amount of precipitation hardening of which is large, both ductility and stretch-flangeability are improved at a tensile strength of 780 MPa or higher, and excellent tensile fatigue properties are exhibited; and a method for producing the hot-rolled high strength steel sheet. A hot-rolled high strength steel sheet having a composition including, in percent by mass, C: 0.06% to 0.15%, Si: 1.2% or less, Mn: 0.5% to 1.6%, P: 0.04% or less, S: 0.005% or less, Al: 0.05% or less, and Ti: 0.03% to 0.20%, the balance being Fe and incidental impurities, wherein the steel sheet has a structure in which the volume fraction of ferrite is 50% to 90%, the balance is substantially bainite, the total volume fraction of ferrite and bainite is 95% or more, precipitates containing Ti are precipitated in the ferrite, and the precipitates have an average diameter of 20 nm or less; and 80% or more of the Ti content in the steel is precipitated. | 02-26-2009 |
20090071578 | Method for manufacturing a high carbon hot-rolled steel sheet - A method for manufacturing a high carbon hot-rolled steel sheet. The method including the steps of hot-rolling, primary cooling, secondary cooling, coiling, acid-washing and annealing. The primary cooling step is to cool the hot-rolled steel sheet down to a cooling termination temperature of 450° C. to 600° C. at a cooling rate of higher than 120° C./sec. The secondary cooling step is to apply a secondary cooling to hold the primarily cooled hot-rolled steel sheet at a temperature of 450° C. to 650° C. until coiling. | 03-19-2009 |
20090126836 | High Carbon Hot Rolled Steel Sheet and method for manufacturing same - A high carbon hot-rolled steel sheet, as a hot-rolled spheroidizing annealed material, having both excellent stretch-flange formability and excellent homogeneity of hardness in the sheet thickness direction is provided by a manufacturing method having the steps of: hot-rolling a steel containing 0.2 to 0.7% C by mass at finishing temperatures of (A | 05-21-2009 |
20090173415 | Steel Sheet Excellent In Fine Blanking Performance and Manufacturing Method of the Same - A steel sheet excellent in FB performance-and also excellent in fabrication performance after FB working and a manufacturing method of the same are provided. The steel sheet is a steel sheet having a composition containing from 0.1 to 0.5% of C, not more than 0.5% of Si and from 0.2 to 1.5% of Mn in terms of % by mass, with P and S being adjusted at proper ranges, and having a structure in which a ferrite has an average grain size of from 1 to 10 μm, cementite has a spheroidization ratio of 80% or more, and of the cementite, an amount S | 07-09-2009 |
20090205756 | HOT-ROLLED THIN STEEL SHEET WITH EXCELLENT FORMABILITY AND EXCELLENT STRENGTH AND TOUGHNESS AFTER HEAT TREATMENT, AND METHOD FOR MANUFACTURING THE SAME - Provided is a hot-rolled thin steel sheet having a thickness of less than 6 mm and having high strength showing a tensile strength of 440 MPa or more, excellent formability, and excellent strength and toughness after heat treatment and a method of manufacturing the same. A steel base material containing 0.10 to 0.20% of C, and Si, Mn, Al, P, S, and N adjusted to suitable amount ranges, and 0.01 to 0. 15% of Ti and 0.0005 to 0.0050% of B is hot rolled so as to have a finishing temperature of finish rolling of 820 to 880° C.; after the completion of the rolling, the hot-rolled thin steel sheet is cooled to a surface temperature range of 550 to 650° C. at a surface cooling rate of 15 to 50° C./s; and the hot-rolled thin steel sheet is coiled at the temperature range. | 08-20-2009 |
20090260729 | HIGH-CARBON HOT-ROLLED STEEL SHEET AND METHOD FOR PRODUCING THE SAME - A high-carbon hot-rolled steel sheet with excellent width-direction homogeneity is provided. The steel sheet contains 0.2% to 0.7% carbon, 0.01% to 1.0% silicon, 0.1% to 1.0% manganese, 0.03% or less phosphorus, 0.035% or less sulfur, 0.08% or less aluminum, and 0.01% or less nitrogen, and the balance is iron and incidental impurities. The structure is such that the average ferrite grain size of edge parts of the steel sheet is less than 35 μm, the average ferrite grain size of a part closer to the center of the steel sheet than the edge parts is less than 20 μm, and the average carbide grain size is 0.10 μm or more and less than 2.0 μm. The steel sheet is produced by roughly rolling the steel, finish-rolling the steel at a finishing temperature of more than (Ar3+40° C.), cooling the steel at a cooling rate of more than 120° C./s within two seconds after the finish rolling to a cooling termination temperature of more than 550° C. and less than 650° C., coiling the steel at a temperature of 550° C. or less, pickling the steel, and subjecting the steel to spheroidizing annealing at a temperature of 670° C. to the Ac1 transformation point by a batch annealing method. | 10-22-2009 |
20100059149 | HIGH STRENGTH HOT ROLLED STEEL PLATE FOR SPIRAL LINE PIPE SUPERIOR IN LOW TEMPERATURE TOUGHNESS AND METHOD OF PRODUCTION OF SAME - The present invention provides hot rolled steel plate for spiral pipe superior in low temperature toughness, thick in gauge, for example, having a plate thickness of 14 mm or more, and having a high strength of the API-X65 standard or more spiral pipe and a method of production of the same, that is, steel plate containing, by mass %, C: 0.01 to 0.1%, Si: 0.05 to 0.5%, Mn: 1 to 2%, P≦0.03%, S≦0.005%, O≦0.003%, Al: 0.005 to 0.05%, N: 0.0015 to 0.006%, Nb: 0.005 to 0.08%, Ti: 0.005 to 0.02%, N−14/48×Ti>0%, Nb−93/14×(N−14/48×Ti>0.005%, Mo: 0.01% to less than 0.1%, Cr: 0.01 to 0.3%, and Cu: 0.01 to 0.3%, and having a balance of Fe and unavoidable impurities, characterized in that an elongation rate of a microstructure unit in a cross-section in the pipe circumferential direction after pipemaking is 2 or less. | 03-11-2010 |
20100282376 | ULTRA SOFT HIGH CARBON HOT ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING SAME - An ultra soft high carbon hot-rolled steel sheet has excellent workability. The steel sheet is a high carbon hot-rolled steel sheet containing 0.2 to 0.7% C, and has a structure in which mean grain size of ferrite is 20 μm or larger, the volume percentage of ferrite grains having 10 μm or smaller size is 20% or less, mean diameter of carbide is in a range from 0.10 μm to smaller than 2.0 μm, the percentage of carbide grains having 5 or more of aspect ratio is 15% or less, and the contact ratio of carbide is 20% or less. | 11-11-2010 |
20100314010 | HIGH-STRENGTH HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING SAME - A high-strength hot-rolled steel sheet has a tensile strength (TS) of 540 to 780 MPa, only small variations in strength, and excellent uniformity in strength using a general-purpose Ti-containing steel sheet, which is inexpensive. The high-strength hot-rolled steel sheet includes, on a mass percent basis, 0.05%-0.12% C, 0.5% or less Si, 0.8%-1.8% Mn, 0.030% or less P, 0.01% or less S, 0.005%-0.1% Al, 0.01% or less N, 0.030%-0.080% Ti, and the balance being Fe and incidental impurities. The microstructure have a bainitic ferrite fraction of 70% or more, and the amount of Ti present in a precipitate having a size of less than 20 nm is 50% or more of the value of Ti* calculated using formula ( | 12-16-2010 |
20100319819 | HIGH-STRENGTH HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING SAME - A high-strength hot-rolled steel sheet has a tensile strength (TS) of 540 to 780 MPa, only small variations in strength, and excellent uniformity in strength using a general-purpose Ti-containing steel sheet, which is inexpensive. The high-strength hot-rolled steel sheet includes, on a mass percent basis, 0.05%-0.12% C, 0.5% or less Si, 0.8%-1.8% Mn, 0.030% or less P, 0.01% or less S, 0.005%-0.1% Al, 0.01% or less N, 0.030%-0.080% Ti, and the balance being Fe and incidental impurities. The microstructure have a volume fraction of polygonal ferrite of 70% or more, and the amount of Ti present in a precipitate having a size of less than 20 nm is 50% or more of the value of Ti* calculated using formula (1): Ti*=[Ti]−48/14×[N] (1) where [Ti] and [N] represent a Ti content (percent by mass) and a N content (percent by mass), respectively, of the steel sheet. | 12-23-2010 |
20110100516 | Bake Hardening Steel with Excellent Surface Properties and Resistance to Secondary Work Embrittlement, and Preparation Method Thereof - Provided are a bake hardening steel having a crystalline grain size of ASTM No. 9 or more and a method for preparing the bake hardening steel by controlling the winding, rolling and cooling conditions. The bake hardening steel includes: C:0.0016˜0.0025%, Si:0.02% or less, P:0.01˜0.05%, S:0.01% or less, sol.Al:0.08˜0.12%, N:0.0025% or less, Ti:0.003% or less, Nb:0.003˜0.011%, Mo:0.01˜0.1%, B:0.0005˜0.0015% or less, balance Fe and other inevitable impurities, wherein % is weight %, and Mn and P satisfy the relation of −30(° C.)≧803P−24.4Mn−58. | 05-05-2011 |
20110297281 | HIGH STRENGTH HOT ROLLED STEEL SHEET EXCELLENT IN BORE EXPANDING WORKABILITY AND METHOD FOR PRODUCTION THEREOF - A high-strength hot-rolled steel sheet containing C: 0.05 to 0.15%, Si: no more than 1.50% (excluding 0%), Mn: 0.5 to 2.5%, P: no more than 0.035% (excluding 0%), S: no more than 0.01% (including 0%), Al: 0.02 to 0.15%, and Ti: 0.05 to 0.2%, which is characterized in that its metallographic structure is composed of 60 to 95 vol % of bainite and solid solution-hardened or precipitation-hardened ferrite (or ferrite and martensite) and its fracture appearance transition temperature (vTrs) is no higher than 0° C. as obtained by impact tests. (% in terms of % by weight) | 12-08-2011 |
20120018062 | METHOD OF HOT-ROLLED THIN STEEL SHEET WITH EXCELLENT FORMABILITY AND EXCELLENT STRENGTH AND TOUGHNESS AFTER HEAT TREATMENT - A method of manufacturing a hot-rolled thin steel sheet includes: hot-rolling a steel base material having a composition containing, as mass %, C: 0.10 to 0.20%, Si: 0.01 to 1.0%, Mn: 0.5 to 2.0%, P: 0.03% or less, S: 0.01% or less, Al: 0.01 to 0.10%, N: 0.005% or less, Ti: 0.01 to 0.15%, B: 0.0005 to 0.0050%, the balance of Fe, and unavoidable impurities at a finishing temperature of finish rolling of 820 to 880° C. to produce a hot-rolled steel sheet with a thickness of less than 6 mm; cooling the hot-rolled steel sheet to a temperature range on a surface of the hot-rolled steel sheet to 550 to 650° C. at a surface cooling rate of 15 to 50° C. per second; and coiling the hot-rolled steel sheet at the temperature range. | 01-26-2012 |
20120024434 | METHOD FOR PRODUCING STRIPS OF METAL, AND PRODUCTION LINE FOR PERFORMING THE METHOD - The invention relates to a method of and a plant for making hot-rolled strips of cast metal, wherein the cast strip is subjected as a rough strip to at least a first step for momogenizing the grain structure in a protective gas and the cast strip is then subjected to at least a further heat-treatment step before it is rolled to reduce its thickness. After the thickness reduction the cast strip is subjected to a second step of homogenization or recrystallization of its grain structure before finally the strip is passed to a cutter and a finished rolled hot piece is severed from the following strip. | 02-02-2012 |
20120138197 | HIGH-STRENGTH HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME - A steel sheet contains, on a mass percent basis, 0.03%-0.12% C, 0.5% or less Si, 0.8%-1.8% Mn, 0.030% or less P, 0.01% or less S, 0.005%-0.1% Al, 0.01% or less N, 0.035%-0.100% Ti, and the balance being Fe and incidental impurities and has microstructures with a fraction of polygonal ferrite of 80% or more, the polygonal ferrite having an average grain size of 5 to 10 μm. The amount of Ti present in a precipitate having a size of less than 20 nm is 70% or more of the value of Ti* calculated using expression (1): | 06-07-2012 |
20120222786 | Manufacturing Method of Carbon Steel Sheet Superior in Formability - A carbon steel sheet having high formability due to a microscopic and uniform carbide distribution and having a good characteristic of final heat treatment, and a manufacturing method thereof. The carbon steel sheet having excellent formability includes, in wt %, C at 0.2-0.5%, Mn at 0.1-1.2%, Si at less than or equal to 0.4%, Cr at less than or equal to 0.5%, Al at 0.01-0.1%, S at less than or equal to 0.012%, Ti at less than or equal to 0.5×48/14×[N] % to 0.03% when the condition of B and N is not satisfied, B at 0.0005-0.0080%, N at less than or equal to 0.006%, Fe, and extra inevitable elements; an average size of carbide is less than or equal to 1 μm; and an average grain size of ferrite is less than or equal to 5 μm. | 09-06-2012 |
20120279620 | HIGH STRENGTH HOT-ROLLED STEEL PLATE EXHIBITING EXCELLENT ACID PICKLING PROPERTY, CHEMICAL CONVERSION PROCESSABILITY, FATIGUE PROPERTY, STRETCH FLANGEABILITY, AND RESISTANCE TO SURFACE DETERIORATION DURING MOLDING, AND HAVING ISOTROPIC STRENGTH AND DUCTILITY, AND METHOD FOR PRODUCING SAID HIGH STRENGTH HOT-ROLLED STEEL PLATE - This high strength hot-rolled steel sheet includes: in terms of percent by mass, C: 0.05 to 0.12%; Si: 0.8 to 1.2%; Mn: 1.6 to 2.2%; Al: 0.30 to 0.6%; P: 0.05% or less; S: 0.005% or less; and N: 0.01% or less, with the remainder being Fe and unavoidable impurities, wherein a microstructure includes specific ranges (in area %) of ferrite phases as well as martensite phases, and a maximum concentration of Al detected by a glow discharge emission spectroscopic analysis is in a range of 0.75 mass % or less in a region from a surface of the steel sheet to a thickness of 500 nm after being acid-pickled. | 11-08-2012 |
20130061989 | HIGH STRENGTH HOT-ROLLED STEEL SHEET HAVING EXCELLENT STRETCH FLANGEABILITY AND FATIGUE RESISTANCE AND METHOD FOR MANUFACTURING THE SAME - A high strength hot-rolled steel sheet has a tensile strength of not less than 780 MPa and exhibits excellent stretch flangeability and excellent fatigue resistance. A steel has a composition containing C at 0.05 to 0.15%, Si at 0.2 to 1.2%, Mn at 1.0 to 2.0%, P at not more than 0.04%, S at not more than 0.005%, Ti at 0.05 to 0.15%, Al at 0.005 to 0.10% and N at not more than 0.007%. | 03-14-2013 |
20130133790 | HIGH TENSILE STRENGTH HOT ROLLED STEEL SHEET HAVING EXCELLENT FORMABILITY AND METHOD FOR MANUFACTURING THE SAME - Described is a high tensile strength hot rolled steel sheet having high strength and formability, and a manufacturing method. It has tensile strength≧980 MPa and excellent formability, and specifically identified ranges by mass % of C, Si, Mn, P, S, N, Al, Ti, V, Solute V, and Solute Ti; (ii) microstructure with fine carbides dispersion precipitated therein, the fine carbides containing Ti and V and having the average particle diameter<10 nm, as well as volume ratio with respect to the entire microstructure≧0.007; and matrix as ferrite phase having area ratio with respect to the entire microstructure≧97%. C, Ti, V, S and N satisfy (1) Ti≧0.08+(N/14×48+S/32×48) and (2) 0.8≦(Ti/48+V/51)/(C/12)≦1.2, where “C”, “Ti”, “V”, “S” and “N” represent contents (mass %) of corresponding elements, respectively. | 05-30-2013 |
20130160904 | HIGH STRENGTH HOT ROLLED STEEL SHEET HAVING EXCELLENT TOUGHNESS AND METHOD FOR MANUFACTURING THE SAME - The steel sheet includes C: 0.04 to 0.12%, Si: 0.5 to 1.2%, Mn: 1.0 to 1.8%, P: not more than 0.03%, S: not more than 0.0030%, Al: 0.005 to 0.20%, N: not more than 0.005% and Ti: 0.03 to 0.13%, the balance being Fe and inevitable impurities, includes a microstructure containing a bainite phase at an area fraction exceeding 95% and having an average grain diameter of not more than 3 μm, has a difference ΔHv1 of not more than 50 between a Vickers hardness value at 50 μm from the surface and a Vickers hardness value at ¼ of a sheet thickness, has a difference ΔHv2 of not more than 40 between the Vickers hardness value at ¼ of the sheet thickness and a Vickers hardness value at ½ of the sheet thickness. | 06-27-2013 |
20130167985 | HIGH STRENGTH HOT ROLLED STEEL SHEET HAVING EXCELLENT BENDABILITY AND METHOD FOR MANUFACTURING THE SAME - A steel sheet including C at 0.05 to 0.15%, Si at 0.2 to 1.2%, Mn at 1.0 to 2.0%, P at not more than 0.04%, S at not more than 0.0030%, Al at 0.005 to 0.10%, N at not more than 0.005% and Ti at 0.03 to 0.13%, the balance being Fe and inevitable impurities, includes surface regions having an area fraction of bainite of less than 80% and an area fraction of a ferrite phase with a grain diameter of 2 to 15 μm of not less than 10%, the surface regions extending from both surfaces of the steel sheet each to a depth of 1.5 to 3.0% relative to a total sheet thickness, as well as an inner region other than the surface regions having an area fraction of a bainite phase of more than 95%, and has a tensile strength of not less than 780 MPa. | 07-04-2013 |
20130186526 | HOT-ROLLED STEEL SHEET HAVING EXCELLENT COLD FORMABILITY AND HARDENABILITY AND METHOD FOR MANUFACTURING THE SAME - Hot-rolled steel has a chemical composition containing, by mass%, C: 0.18% or more and 0.29% or less, N: 0.0050% or less, Ti: 0.002% or more and 0.05% or less, B: 0.0005% or more and 0.0050% or less, and appropriately controlled amounts of Si, Mn, P, S, Al, and a tensile strength of 500 MPa or less with a variation in tensile strength of 60 MPa or less throughout a region including the edges in the width direction of the steel sheet, and having excellent cold formability and hardenability. | 07-25-2013 |
20130199678 | HIGH STRENGTH HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME - A high strength hot-rolled steel sheet with a tensile strength of not less than 590 MPa which exhibits excellent bake hardenability and stretch-flangeability has a chemical composition including, in terms of mass %, C at 0.040 to 0.10%, Si at not more than 0.3%, Mn at 1.7 to 2.5%, P at not more than 0.030%, S at not more than 0.005%, Al at not more than 0.1% and N at 0.006 to 0.025%, and microstructure wherein a bainite phase represents not less than 60%, the total of a ferrite phase and a pearlite phase represents not more than 10%, and the bainite phase includes grains among which cementite grains have been precipitated at not less than 1.4×10 | 08-08-2013 |
20130206289 | HIGH-STRENGTH HOT-ROLLED STEEL SHEET HAVING EXCELLENT FORMABILITY AND METHOD FOR MANUFACTURING THE SAME - A high-strength hot-rolled steel sheet having excellent formability has a composition containing, by mass, 0.04% to 0.1% of C, 0.3% to 1.3% of Si, 0.8% to 1.8% of Mn, 0.03% or less of P, 0.005% or less of S, 0.005% or less of N, 0.005% to 0.1% of Al, and at least one element selected from 0.002% to less than 0.03% of Ti, 0.002% to less than 0.03% of V, and 0.002% to less than 0.02% of Nb, the balance being Fe and incidental impurities. The steel sheet has a microstructure in which the area fraction of ferrite phase in the entire structure is 85% or more, the area fraction of bainite phase in the entire structure is 10% or less, the area fraction of phases other than the ferrite and bainite phases in the entire structure is 5% or less, and the area fraction of acicular ferrite phase in the entire ferrite phase is 30% to less than 80%. | 08-15-2013 |
20130233453 | HIGH STRENGTH STEEL SHEET HAVING EXCELLENT FORMABILITY AND METHOD FOR MANUFACTURING THE SAME - A thin high strength steel sheet having excellent formability has a composition which includes, by mass %, 0.08 to 0.15% of C, 0.5 to 1.5% of Si, 0.5 to 1.5% of Mn, 0.01 to 0.1% of Al, and 0.005% or less of N to form a hot rolled sheet is conducted. | 09-12-2013 |
20130276940 | HIGH STRENGTH HOT ROLLED STEEL SHEET HAVING EXCELLENT FATIGUE RESISTANCE AND METHOD FOR MANUFACTURING THE SAME - A steel having a composition that includes C: 0.05 to 0.15%, Si: 0.2 to 1.2%, Mn: 1.0 to 2.0%, Al: 0.005 to 0.10%, N: 0.006% or less, and at least one selected from Ti: 0.03 to 0.13%, Nb: 0.02 to 0.10%, and V: 0.02 to 0.15% is subjected to rough rolling at a reduction of 80% or more and finish rolling at a finish rolling delivery temperature in the range of 800 to 950° C. The finish rolled sheet is subjected to cooling including cooling the finish rolled sheet from the finish rolling delivery temperature to a cooling end temperature in the range of 550 to 610° C. at an average cooling rate of 25° C./sec. or more and cooling the finish rolled sheet from the cooling end temperature of the previous process to a coiling temperature at an average cooling rate of 100° C./sec. or more. | 10-24-2013 |
20130319582 | BAINITE-CONTAINING-TYPE HIGH-STRENGTH HOT-ROLLED STEEL SHEET HAVING EXCELLENT ISOTROPIC WORKABILITY AND MANUFACTURING METHOD THEREOF - The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100}<011> to {223}<110> orientation group at a sheet thickness center portion being a range of ⅝ to ⅜ in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 4.8 or less, an average crystal grain diameter is 10 μm or less and vTrs is −20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase. | 12-05-2013 |
20130319583 | HIGH-PURITY FERRITIC STAINLESS STEEL SHEET WITH EXCELLENT OXIDATION RESISTANCE AND HIGH-TEMPERATURE STRENGTH, AND PROCESS FOR PRODUCING THE SAME - The present invention provides a low-alloy high-purity ferritic stainless steel sheet provided with improved oxidation resistance and high-temperature strength by utilizing Sn addition in trace amounts without relying on excessive alloying of Al and Si which reduces fabricability and weldability or addition of rare elements such as Nb, Mo, W, and rare earths, and a process for producing the same. The high-purity ferritic stainless steel sheet includes C: 0.001 to 0.03%, Si: 0.01 to 2%, Mn: 0.01 to 1.5%, P: 0.005 to 0.05%, S: 0.0001 to 0.01%, Cr: 16 to 30%, N: 0.001 to 0.03%, Al: 0.05 to 3%, and Sn: 0.01 to 1% (% by mass), with the remainder being Fe and unavoidable impurities. A stainless steel slab having such steel components is heated, wherein an extraction temperature is 1100 to 1250° C., and a winding temperature after hot rolling is 650° C. or lower. A hot-rolled sheet is annealed at 900 to 1050° C., and cooled at 10° C./sec or less over a temperature range of 550 to 850° C. | 12-05-2013 |
20140000769 | HOT ROLLED STEEL SHEET AND METHOD OF PRODUCING SAME | 01-02-2014 |
20140007993 | HIGH STRENGTH HOT ROLLED STEEL SHEET HAVING EXCELLENT BLANKING WORKABILITY AND METHOD FOR MANUFACTURING THE SAME - A high strength hot rolled steel sheet having excellent blanking workability is provided. The composition contains C: 0.050 to 0.15%, Si: 0.1 to 1.5%, Mn: 1.0 to 2.0%, P: 0.03% or less, S: 0.0030% or less, Al: 0.01 to 0.08%, Ti: 0.05 to 0.15%, N: 0.005% or less, and the balance being Fe and unavoidable impurities. More than 95% of the microstructure is formed of a bainite phase in terms of area fraction. Average grain diameters of the bainite phase in a region having a thickness equal to ¼ of the sheet thickness from the surface in the sheet thickness direction is 5 μm or less in an L-direction cross section and 4 μm or less in a C-direction cross section. The number of crystal grains extended in the rolling direction and having an aspect ratio of 5 or more is 7 or less in a sheet thickness center portion. | 01-09-2014 |
20140069556 | HIGH CARBON THIN STEEL SHEET AND METHOD FOR PRODUCING SAME - A high carbon steel sheet having a chemical composition containing C: 0.20% to 0.50%, Si: 1.0% or less, Mn: 2.0% or less, P: 0.03% or less, S: 0.02% or less, sol. Al: 0.08% or less, N: 0.02% or less, and the remainder composed of Fe and incidental impurities, on a percent by mass basis, and a microstructure composed of ferrite and cementite, wherein the fraction of pro-eutectoid ferrite, among the ferrite, in the whole steel microstructure is 20% or more and less than 50%, the average grain size dc of the cementite in the region from the position at one-quarter of the sheet thickness of the steel sheet to the sheet thickness center is 0.50 to 1.5 μm, and the average grain size ds of the cementite in the region from the surface of the steel sheet to the position at one-quarter of the sheet thickness satisfies ds/dc≦0.8. | 03-13-2014 |
20140190597 | HOT COIL FOR LINE PIPE USE AND METHOD OF PRODUCTION OF SAME - The present invention provides a hot coil for line pipe use which can reduce deviation in ordinary temperature strength and improve low temperature toughness despite the numerous restrictions in production conditions due to the coiling step and provides a method of production of the same, specifically makes the steel plate stop for a predetermined time between rolling passes in the recrystallization temperature range and performs cooling by two stages after hot rolling so as to thereby make the steel structure at the center part of plate thickness and effective crystal grain size of 3 to 10 μm, make the total of the area ratios of bainite and acicular ferrite 60 to 99%, and make the absolute value of A-B 0 to 30% when the totals of the area ratios of bainite and acicular ferrite at any two portions are designated as respectively A and B. | 07-10-2014 |
20140216614 | FERRITIC STAINLESS STEEL PLATE WHICH HAS EXCELLENT RIDGING RESISTANCE AND METHOD OF PRODUCTION OF SAME - The present invention focuses on Sn and has as its problem to not only improve the corrosion resistance and rust resistance of Cr-containing ferritic stainless steel but also improve the ridging resistance. | 08-07-2014 |
20140251513 | HIGH-STRENGTH HOT ROLLED STEEL SHEET WITH EXCELLENT BENDABILITY AND LOW-TEMPERATURE TOUGHNESS, AND METHOD FOR MANUFACTURING THE SAME - A high-strength hot rolled steel sheet with excellent bendability and low-temperature toughness includes a chemical composition including, in mass %, C: 0.08 to 0.25%, Si: 0.01 to 1.0%, Mn: 0.8 to 2.1%, P: not more than 0.025%, S: not more than 0.005% and Al: 0.005 to 0.10%, the balance including Fe and inevitable impurities, and a microstructure having a bainite phase and/or a tempered martensite phase as a main phase, the average grain diameter of prior austenite grains being not more than 20 μm as measured with respect to a cross section parallel to a rolling direction and not more than 15 μm as measured with respect to a cross section perpendicular to the rolling direction. | 09-11-2014 |
20140261914 | METHOD OF PRODUCING HOT ROLLED HIGH STRENGTH DUAL PHASE STEELS USING ROOM TEMPERATURE WATER QUENCHING - A process for manufacturing hot rolled high strength dual phase steels. In some instances, hot rolled strip is continuously cooled to less than 100° C. prior to coiling using a cooling rate between 40-70° C./second. In other instances, hot rolled strip is cooled to less than 100° C. prior to coiling using a step cooling treatment. In yet other instances, hot rolled strip is continuously cooled to less than 100° C. prior to coiling using a cooling rate between 70-100° C./second. For hot rolled strip subjected to a cooling rate between 40-70° C./second, or subjected to the step cooling treatment, hot rolled steel sheet with a tensile strength greater than 590 MPa is produced. For hot rolled strip subjected to a cooling rate between 70-100° C./second, hot rolled steel sheet with a tensile strength greater than 690 MPa is produced. Also, the hot rolled steel sheet has a ferrite plus martensite microstructure free of pearlite and bainite. | 09-18-2014 |
20140261915 | LINE PIPE STEELS AND PROCESS OF MANUFACTURING - A process for producing high strength steel is provided. The process includes providing a steel slab having a chemical composition in weight percent within a range of 0.025-0.07 C, 1.20-1.70 Mn, 0.050-0.085 Nb, 0.022 max Ti, 0.065 max N, 0.0040 max S, 0.10-0.45 Si, 0.070 max P, with the balance being Fe and incidental impurities. The steel slab is soaked within a temperature range of 1150-1230° C., hot rolled using a roughing treatment in order to produce a transfer bar and further hot rolled using a finishing treatment in order to produce hot rolled strip. The hot rolled strip is cooled using a cooling rate between 10-100° C./second (sec) and coiled within a temperature range of 580-400° C. Finally, the coiled hot rolled strip has a yield strength of at least 80 ksi and a DWTT transition temperature equal or less than −20° C. | 09-18-2014 |
20140299237 | METHOD FOR MANUFACTURING A HIGH-STRENGTH STRUCTURAL STEEL AND A HIGH-STRENGTH STRUCTURAL STEEL PRODUCT - The invention relates to a method for manufacturing a high-strength structural steel and to a high-strength structural steel product. The method comprises a providing step for providing a steel slab, a heating step ( | 10-09-2014 |
20140299238 | HOT-ROLLED STEEL SHEET AND METHOD FOR PRODUCING SAME - A hot rolled steel sheet has a chemical composition including, by mass %, C: 0.060% to 0.120%; Si: 0.10% to 0.70%; Mn: 1.00% to 1.80%; P: 0.10% or less; S: 0.010% or less; Al: 0.01% to 0.10%; N: 0.010% or less; Nb: 0.010% to 0.100%, wherein Nb is contained so that content of solute Nb is 5% or more relative to the total Nb content; the balance being Fe and incidental impurities. The hot rolled steel sheet has a microstructure containing ferrite of not more than 15 μm in average crystal grain diameter by a volume fraction of not less than 75%, the balance being low-temperature-induced phases. The hot rolled steel sheet can be suitably utilized for manufacturing a cold rolled steel sheet or hot-dip galvanized steel sheet having a tensile strength of 590 MPa or more, excellent in material homogeneity and capable of giving excellent cold rolling property. | 10-09-2014 |
20140332122 | HIGH CARBON HOT ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME (AS AMENDED) - A high carbon hot rolled steel sheet having a chemical composition containing by mass %, C: 0.20% to 0.48%, Si: 0.1% or less, Mn: 0.5% or less, P: 0.03% or less, S: 0.01% or less, Al: 0.1% to 0.6%, Cr: 0.05% to 0.5%, B: 0.0005% to 0.0050%, Ca: 0.0010% to 0.0050%, and the remainder composed of Fe and incidental impurities, on a percent by mass basis, where the average amount of N in a surface layer portion from the surface to the position at a depth of 0.1 mm in thickness direction is 0.1% or more and the average amount of N in the central portion in thickness is 0.01% or less, and a microstructure composed of ferrite and carbides, wherein the average grain size of the ferrite is 10 to 20 and the spheroidization ratio of the carbides is 90% or more. | 11-13-2014 |
20140338801 | HIGH-STRENGTH HOT-ROLLED STEEL SHEET AND METHOD FOR PRODUCING SAME - A high-strength hot-rolled steel sheet including a chemical composition containing, in percent by mass, 0.05% to 0.12% of C, 0.05% to 1.0% of Si, 0.5% to 1.8% of Mn, 0.04% or less of P, 0.0030% or less of S, 0.005% to 0.07% of Al, 0.006% or less of N, 0.05% to 0.15% of Ti, and the balance being Fe and incidental impurities, in which, in a region in the range of ⅛ to ⅜ of the sheet thickness, the content of Ti*, which is Ti existing as precipitates, is 0.3×[Ti] to 0.6×[Ti], where [Ti] is the Ti content, and the steel sheet has a microstructure in which the area fraction of the bainite phase in the entire structure is more than 95%. | 11-20-2014 |
20140352852 | HOT ROLLED HIGH TENSILE STRENGTH STEEL SHEET AND METHOD FOR MANUFACTURING SAME - The steel sheet has a chemical composition containing, by mass %, C: 0.04-0.08%, Si: 0.50% or less, Mn: 0.8-2.2%, P: 0.02% or less, S: 0.006% or less, Al: 0.1% or less, N: 0.008% or less, and Cr: 0.05-0.8%, and further Nb: 0.01-0.08%, V: 0.001-0.12%, and Ti: 0.005-0.04% in adjusted amounts, with the balance including Fe and incidental impurities. The steel sheet has a surface layer having a microstructure containing bainite as a main phase, martensite as a second phase in a volume fraction of 0.5-4%, and at lease one of ferrite phase, pearlite, and cementite as a third phase in a total volume fraction of 10% or less. | 12-04-2014 |
20140360634 | HOT ROLLED STEEL SHEET FOR COLD ROLLED STEEL SHEET, HOT ROLLED STEEL SHEET FOR GALVANIZED STEEL SHEET, AND METHOD FOR PRODUCING THE SAME - A hot rolled steel sheet having a chemical composition containing, by mass %, C: 0.04% or more and 0.20% or less, Si: 0.7% or more and 2.3% or less, Mn: 0.8% or more and 2.8% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.1% or less, N: 0.008% or less, and the balance being Fe and inevitable impurities. The microstructure of the hot rolled steel sheet includes ferrite and pearlites, in which the area ratio of the ferrite is 75% or more and less than 95%, the mean grain size of the ferrite is 5 μm or more and 25 μm or less, the area ratio of pearlite is 5% or more and less than 25%, the mean grain size of pearlite is 2.0 μm or more, and the mean free path of pearlite is 5 μm or more. | 12-11-2014 |
20150090376 | HIGH CARBON HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME - A high carbon hot rolled steel sheet and a method for manufacturing the same are provided, wherein excellent cold workability and excellent hardenability are obtained stably. The high carbon hot rolled steel sheet has a composition containing C: 0.20% to 0.48%, Si: 0.1% or less, Mn: 0.5% or less, P: 0.03% or less, S: 0.01% or less, sol. Al: more than 0.10% and 1.0% or less, N: 0.005% or less, B: 0.0005% to 0.0050%, and the remainder composed of Fe and incidental impurities, on a percent by mass basis, and a microstructure composed of ferrite and cementite, wherein the average grain size of the above-described ferrite is 10 to 20 μm and the spheroidization ratio of the above-described cementite is 90% or more. | 04-02-2015 |
20150101717 | HIGH STRENGTH HOT-ROLLED STEEL SHEET HAVING EXCELLENT DUCTILITY, STRETCH FLANGEABILITY AND UNIFORMITY AND METHOD OF MANUFACTURING THE SAME - A slab has a steel composition including 0.020% to 0.065% of C, 0.1% or less of Si, 0.40% to less than 0.80% of Mn, 0.030% or less of P, 0.005% or less of S, 0.08% to 0.16% of Ti, 0.005% to 0.1% of Al, 0.005% or less of N, and the balance being Fe and incidental impurities, in which Ti*(=Ti−(48/14)×N) satisfies [Ti*≧0.08] and [0.300≦C/Ti*≦0.375], is subjected to hot rolling to obtain a hot-rolled steel sheet in which the steel microstructure includes, in terms of area fraction, 95% or more of a ferrite phase; the average ferrite grain size is 10 μm or less; the average grain size of Ti carbides precipitated in steel is 10 nm or less; and Ti in the amount of 80% or more of Ti* is precipitated as Ti carbides. | 04-16-2015 |
20150299828 | STEEL SHEET FOR THREE-PIECE CAN AND METHOD FOR MANUFACTURING THE SAME - Provided are a steel sheet for a can having high buckling strength for a can body against an external force and excellent formability when being formed into a shape having a design effect by additionally giving elongation strain in the circumferential direction after the steel sheet having been formed into a cylindrical shape and a method for manufacturing the steel sheet. The chemical composition is controlled to contain, by mass %, C: 0.0005% or more and 0.0035% or less, Si: 0.050% or less, Mn: more than 0.60% and 1.00% or less, P: 0.030% or less, S: 0.020% or less, Al: 0.010% or more and 0.100% or less, N: 0.0030% or less, B: 0.0005% or more, and the balance being Fe and inevitable impurities, in which the relationship B/N≧0.50 is satisfied where B/N represents | 10-22-2015 |
20150299830 | STEEL SHEET FOR SOFT-NITRIDING AND METHOD FOR MANUFACTURING THE SAME - A steel sheet for soft-nitriding has a composition containing: C: 0.05% or more to 0.10% or less; Si: 0.5% or less; Mn: 0.7% or more to 1.5% or less; P: 0.05% or less; S: 0.01% or less; Al: 0.01% or more to 0.06% or less; Cr: 0.5% or more to 1.5% or less; Nb: 0.005% or more to 0.025% or less; and N: 0.005% or less, on a mass percent basis, such that C and Nb satisfy 0.10≦Nb/C≦0.30 (where C and Nb are respective contents of the elements (by mass %)), wherein balance comprises Fe and incidental impurities, and a microstructure that is a complex-phase microstructure containing ferrite and pearlite, and the microstructure having a ratio of a microstructure other than the ferrite and the pearlite of 1% or less, and the microstructure having a ratio of polygonal ferrite in the ferrite of less than 50%. | 10-22-2015 |
20150315683 | HOT-ROLLED STEEL SHEET AND METHOD FOR PRODUCING SAME - A hot-rolled steel sheet includes, as a chemical composition, by mass %, C: 0.030% to 0.10%, Mn: 0.5% to 2.5%, and Si+Al: 0.100% to 2.5%, in which the steel sheet has a microstructure including, by area fraction, ferrite: 80% or more, martensite: 3% to 15.0%, and pearlite: less than 3.0%, in which a number density of martensite having an equivalent circle diameter of 3 μm or more at a position which is at a depth of ¼ of the steel sheet thickness from the surface of the steel sheet, is 5.0 pieces/10000 μm | 11-05-2015 |
20150354034 | STEEL SHEET FOR SOFT-NITRIDING AND METHOD FOR MANUFACTURING THE SAME - A steel sheet for soft-nitriding has a composition containing: C: 0.05% or more to 0.10% or less; Si: 0.5% or less; Mn: 0.7% or more to 1.5% or less; P: 0.05% or less; S: 0.01% or less; Al: 0.01% or more to 0.06% or less; Cr: 0.5% or more to 1.5% or less; V: 0.03% or more to 0.30% or less; and N: 0.005% or less, on a mass percent basis, wherein a ratio of amount of solute V to the V content (amount of solute V/V content) is more than 0.50, and balance comprises Fe and incidental impurities, and a complex-phase microstructure containing ferrite and pearlite. | 12-10-2015 |
20150368736 | HOT-ROLLED STEEL SHEET FOR HIGH STRENGTH LINEPIPE - A hot-rolled steel sheet for a high strength linepipe having a metallic structure composed of bainitic-ferrite and a method for making the same. The steel sheet having a chemical composition containing, by mass %, C: 0.02% or more and 0.06% or less, Si: 0.05% or more and 0.25% or less, Mn: 0.60% or more and 1.10% or less, P: 0.008% or less, S: 0.0010% or less, Nb: 0.010% or more and 0.060% or less, Ti: 0.001% or more and 0.020% or less, Mo: 0.05% or less, Cr: 0.05% or more and 0.50% or less, Al: 0.01% or more and 0.08% or less, Ca: 0.0005% or more and 0.0050% or less, O: 0.005% or less, one or more selected from among Cu: 0.50% or less, Ni: 0.50% or less, and V: 0.10% or less, and the balance being Fe and inevitable impurities, in which the ratio of the hardness of a center segregation part to the hardness of a non-segregation part is less than 1.20 and the relationship SP≦1.90 is satisfied. | 12-24-2015 |
20150368737 | HOT-ROLLED STEEL SHEET FOR HIGH STRENGTH LINEPIPE HAVING TENSILE STRENGTH OF 540 MPA OR MORE - A hot-rolled steel sheet for a high strength linepipe having a tensile strength of 540 MPa or more and a method for making the same. The steel sheet having a chemical composition containing, by mass %, C: 0.02% or more and 0.06% or less, Si: 0.05% or more and 0.25% or less, Mn: 0.60% or more and 1.10% or less, P: 0.008% or less, S: 0.0010% or less, Nb: 0.020% or more and 0.060% or less, Ti: 0.001% or more and 0.020% or less, Al: 0.01% or more and 0.08% or less, Ca: 0.0005% or more and 0.0050% or less, one or more selected from among Cu: 0.50% or less, Ni: 0.50% or less, Cr: 0.50% or less, Mo: 0.50% or less, and V: 0.10% or less, and the balance being Fe and inevitable impurities, in which the relationships 0.60≦CP≦0.90 and CM≦3.05 are satisfied. | 12-24-2015 |
20160032431 | STEEL SHEET FOR NITRIDING AND PRODUCTION METHOD THEREFOR - A steel sheet for nitriding has excellent formability and punchability. The steel sheet has a composition including, in percent by mass, 0.02% to 0.08% of C, 0.1% or less of Si, 0.2% to 1.8% of Mn, 0.05% or less of P, 0.02% or less of S, 0.01% to 0.06% of Al, 0.5% to 1.5% of Cr, 0.01% or less of N, and the balance being Fe and incidental impurities; and has a microstructure including ferrite as a main phase and pearlite and/or bainite as a secondary phase. The ferrite has a fraction of 70% or more in the entire microstructure and an average grain diameter of 5 to 25 gm. An average length of the major axis of cementite present in the secondary phase in a cross section in the rolling direction of the steel sheet is 3.0 μm or less. | 02-04-2016 |
20160060723 | HIGH STRENGTH HOT-ROLLED STEEL SHEET AND METHOD OF PRODUCING THE SAME - A high-strength hot-rolled steel sheet has a tensile strength TS of 980 MPa or more and is manufactured by controlling the steel sheet to have a chemical composition containing C: more than 0.1% and 0.2% or less, Si: 0.5% or more and 3.0% or less, Mn: 1.0% or more and 3.5% or less, P: 0.05% or less, S: 0.004% or less, Al: 0.10% or less, N: 0.008% or less, Ti: 0.05% or more and 0.15% or less, V: more than 0.10% and 0.30% or less, and the balance being Fe and inevitable impurities. Surface regions have a microstructure including mainly a ferrite phase, and an inner region has a microstructure including mainly a bainite phase. The proportions of the surface regions in the thickness direction of the steel sheet are 1.0% or more and 5.0% or less of the whole thickness respectively from the upper and lower surfaces of the steel sheet. | 03-03-2016 |
20160076124 | HIGH STRENGTH HOT ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME (AS AMENDED) - A high strength hot rolled steel sheet having a tensile strength TS of 980 MPa or more, has a composition containing, on a percent by mass basis, C: 0.05% or more and 0.18% or less, Si: 1.0% or less, Mn: 1.0% or more and 3.5% or less, P: 0.04% or less, S: 0.006% or less, Al: 0.10% or less, N: 0.008% or less, Ti: 0.05% or more and 0.20% or less, V: more than 0.1% and 0.3% or less, and the balance being Fe and incidental impurities, and has a microstructure including a primary phase and a secondary phase, the primary phase being a bainite phase having an area fraction of more than 85%, the secondary phase being at least one of ferrite phase, martensite phase, and retained austenite phase, the secondary phase having an area fraction of 0% or more and less than 15% in total, the bainite phase having an average lath interval of laths of 400 nm or less, and the laths having an average long axis length of 5.0 μm or less. | 03-17-2016 |
20160145709 | HIGH-CARBON HOT-ROLLED STEEL SHEET AND METHOD FOR PRODUCING THE SAME - There is provided is a high-carbon hot-rolled steel sheet and method for producing the same. The steel sheet has excellent hardenability consistently, even when annealed in a nitrogen atmosphere, and excellent formability. The steel sheet has a hardness in the range of 83 HRB or less and a total elongation of 30% or more before being subjected to a quenching treatment. | 05-26-2016 |
20160145710 | HIGH-CARBON HOT-ROLLED STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME - There is provided a high-carbon hot-rolled steel sheet and method for producing the same. The steel sheet has excellent hardenability consistently, even when annealed in a nitrogen atmosphere, and excellent workability. The steel sheet has a hardness in the range of 65 or less in terms of HRB and a total elongation El of 40% or more before a quenching treatment is performed. | 05-26-2016 |