Patent application number | Description | Published |
20100237548 | STEEL-SHEET CONTINUOUS ANNEALING EQUIPMENT AND METHOD FOR OPERATING STEEL-SHEET CONTINUOUS ANNEALING EQUIPMENT - Steel-sheet continuous annealing equipment includes, in sequence, a pre-heating zone, a heating zone, a soaking zone, a cooling zone, a reheating zone, an overaging zone, and a final cooling zone, and further includes a rapid heating region and a rapid cooling region that are provided within a range from the reheating zone to the final cooling zone (including the reheating zone and the final cooling zone), the rapid heating region allowing rapid heating of a steel sheet at a heating rate of 15° C./s or more and the rapid cooling region allowing rapid cooling, at a cooling rate of 10° C./s or more, of the steel sheet that has been rapidly heated in the rapid heating region. Various steel-sheet products ranging from mild steel sheets to ultrahigh-tensile steel sheets can be produced by performing a heat treatment with such steel-sheet continuous annealing equipment. | 09-23-2010 |
20130022490 | HIGH-STRENGTH STEEL SHEET WITH EXCELLENT WARM WORKABILITY - Disclosed is a high-strength steel plate with excellent warm workability that has a component composition comprising, in mass %, 0.05 to 0.4% C, 0.5 to 3% Si+Al, 0.5 to 3% Mn, no more than 0.15% P (not including 0%), and no more than 0.02% S (including 0%), with the remainder comprising iron and impurities, and a composition that includes a total of 45 to 80% martensite and/or bainitic ferrite in terms of the area ratio relative to the entire composition, 5 to 40% polygonal ferrite in terms of the area ratio relative to the entire composition, and 5 to 20% retained austenite in terms of the area ratio relative to the entire composition, wherein the C concentration (C | 01-24-2013 |
20130236350 | HIGHLY FORMABLE HIGH-STRENGTH STEEL SHEET, WARM WORKING METHOD, AND WARM-WORKED AUTOMOBILE PART - A high-strength steel sheet has a chemical composition including 0.05% to 0.3% of C, 1% to 3% of Si, 0.5% to 3% of Mn, 0% to 0.1% of P, 0.001% to 0.1% of Al, and 0.002% to 0.03% of N, in mass percent; further includes iron and impurities; and has a structure including 50% to 90% of bainitic ferrite, 5% to 20% of retained austenite (γ | 09-12-2013 |
20130259734 | HIGHLY FORMABLE HIGH-STRENGTH STEEL SHEET, WARM WORKING METHOD, AND WARM-WORKED AUTOMOBILE PART - A high-strength steel sheet has a chemical composition including 0.05% to 0.3% of C, 1% to 3% of Si, 0.5% to 3% of Mn, 0% to 0.1% of P, 0% to 0.01% of S, 0.001% to 0.1% of Al, and 0.002% to 0.03% of N in mass percent; further includes iron and impurities; and has a structure including 50% to 90% of bainitic ferrite, 3% or more of retained austenite (γ | 10-03-2013 |
20130330226 | HIGH-STRENGTH STEEL SHEET WITH EXCELLENT DEEP DRAWABILITY AT ROOM TEMPERATURE AND WARM TEMPERATURE, AND METHOD FOR WARM WORKING SAME - This high-strength steel sheet has a component composition containing, in mass %, 0.02 to 0.3% C, 1 to 3% Si, 1.8 to 3% Mn, 0.1% or less P, 0.01% or less S, 0.001 to 0.1% Al, and 0.002 to 0.03% N, the remainder being iron and impurities. The high-strength steel sheet has a structure containing, in terms of area ratio relative to the entire structure, each of the following phases: 50 to 85% bainitic ferrite; 3% or more retained austenite (γ); 10 to 45% martensite and the aforementioned retained austenite (γ); and 5 to 40% ferrite. The ratio between the Mn concentration (Mn | 12-12-2013 |
20140044585 | HOT PRESS-FORMED PRODUCT, PROCESS FOR PRODUCING SAME, AND THIN STEEL SHEET FOR HOT PRESS FORMING - There is provided a hot press-formed product, including a thin steel sheet formed by a hot press-forming method, and having a metallic structure that contains retained austenite at 3% to 20% by volume, whereby balance between strength and elongation can be controlled in a proper range and high ductility can be achieved. | 02-13-2014 |
20140056753 | HOT PRESS-FORMED PRODUCT, PROCESS FOR PRODUCING SAME, AND THIN STEEL SHEET FOR HOT PRESS FORMING - There is provided a hot press-formed product, including a steel sheet formed by a hot press-forming method, and having a metallic structure that contains ferrite at 30% to 80% by area, bainitic ferrite at lower than 30% by area (not including 0% by area), martensite at 30% by area or lower (not including 0% by area), and retained austenite at 3% to 20% by area, whereby balance between strength and elongation can be controlled in a proper range and high ductility can be achieved. | 02-27-2014 |
20140056754 | HOT PRESS-FORMED PRODUCT, PROCESS FOR PRODUCING SAME, AND THIN STEEL SHEET FOR HOT PRESS FORMING - There is provided a hot press-formed product, including a thin steel sheet formed by a hot press-forming method, and having a metallic structure that contains bainitic ferrite at 70% to 97% by area, martensite at 27% by area or lower, and retained austenite at 3% to 20% by area, the remainder structure of which is at 5% by area or lower, whereby balance between strength and elongation can be controlled in a proper range and high ductility can be achieved. | 02-27-2014 |
20140065007 | HOT PRESS-FORMED PRODUCT, PROCESS FOR PRODUCING SAME, AND THIN STEEL SHEET FOR HOT PRESS FORMING - There is provided a hot press-formed product, including a thin steel sheet formed by a hot press-forming method, and having a metallic structure that contains martensite at 80% to 97% by area and retained austenite at 3% to 20% by area, the remainder structure of which is at 5% by area or lower, whereby balance between strength and elongation can be controlled in a proper range and high ductility can be achieved. | 03-06-2014 |
20140161659 | HIGH-STRENGTH HOT-ROLLED STEEL SHEET - This high-strength hot-rolled steel plate contains specific amounts of C, Si, Mn, Al, V and also Ti and/or Nb so as to fulfill C−12(V/51+Ti/48+Nb/93)>0.03, and the rest consists of iron and unavoidable impurities. Ferrite is the main microstructure, the remaining microstructure is one or more selected from the group consisting of bainite, martensite and retained austenite, wherein the average particle diameter of precipitated carbides (the total content of V, Ti and Nb is 0.02% or greater) in the ferrite is less than 6 nm. | 06-12-2014 |
20140271331 | HIGH-STRENGTH STEEL SHEET HAVING EXCELLENT ROOM-TEMPERATURE FORMABILITY AND WARM FORMABILITY, AND WARM FORMING METHOD THEREOF - This high-strength steel plate has a component composition including, by mass %, C: 0.02-0.3%, Si: 1-3%, Mn: 1.8-3%, P: 0.1% or less, S: 0.01% or less, Al: 0.001-0.1%, N: 0.002-0.03%, the rest consisting of iron and impurities. Said steel plate has a microstructure including, in terms of area ratio relative to the entire microstructure, each of the following phases: bainitic ferrite: 50-85%; retained γ; 3% or greater; martensite+the aforementioned retained γ; 10-45%; and ferrite: 5-40%. The C concentration (CγR) in the aforementioned retained austenite is 0.3-1.2 mass %, part or all of the N in the aforementioned component composition is solid solution N, and the amount of said solid solution N is 30-100 ppm. | 09-18-2014 |
20140305553 | HIGH-STRENGTH COLD-ROLLED STEEL SHEET HAVING SMALL VARIATIONS IN STRENGTH AND DUCTILITY AND MANUFACTURING METHOD FOR THE SAME - A high-strength cold-rolled steel sheet has a chemical composition including C of 0.05% to 0.30%, Si of greater than 0% to 3.0%, Mn of 0.1% to 5.0%, P of greater than 0% to 0.1%, S of greater than 0% to 0.02%, Al of 0.01% to 1.0%, and N of greater than 0% to 0.01%, in mass percent, with the remainder including iron and inevitable impurities. The steel sheet has a microstructure containing ferrite as a soft primary phase in an area percentage of 20% to 50% with the remainder including tempered martensite and/or tempered bainite as a hard secondary phase. The ferrite grains are adapted to contain cementite particles having an appropriate size in an appropriate number density. | 10-16-2014 |
20140367002 | HOT-PRESS FORMED PRODUCT AND METHOD FOR MANUFACTURING SAME - A hot-press formed product can be achieved which has regions corresponding to a shock resistant portion and an energy absorption portion within a single formed product without applying a welding method and achieves the balance of high strength and elongation with a high level according to each region by means of having a first forming region exhibiting a metal structure containing martensite: 80-97 area % and retained austenite: 3-20 area % respectively, the remaining structure being 5 area % or less, and a second forming region exhibiting a metal structure containing annealed martensite or annealed bainite: 30-97 area %, martensite as quenched: 0-67 area %, and retained austenite: 3-20 area %. | 12-18-2014 |
20150013856 | METHOD FOR MANUFACTURING PRESS-FORMED PRODUCT AND PRESS-FORMED PRODUCT - In the present invention, a press-formed product is manufactured by heating a steel sheet for hot pressing use to a temperature of 900° C. or above and 1,100° C. or below, the steel sheet for hot pressing use having a predetermined chemical component composition, some of Ti-containing precipitates contained in the steel sheet, each of which having an equivalent circle diameter of 30 nm or less, having an average equivalent circle diameter of 6 nm or less, and the precipitated Ti amount and the total Ti amount in the steel fulfilling the relationship represented by formula (1) shown below, thereafter starting press-forming, and holding at the bottom dead point and cooling to a temperature lower than the martensite transformation starting temperature Ms while securing the average cooling rate of 20° C./s or more within a tool. | 01-15-2015 |
20150027602 | STEEL SHEET FOR HOT PRESSING USE, PRESS-FORMED PRODUCT, AND METHOD FOR MANUFACTURING PRESS-FORMED PRODUCT - A steel sheet for hot pressing use according to the present invention has a specified chemical component composition, wherein some of Ti-containing precipitates contained in the steel sheet, each of which having an equivalent circle diameter of 30 nm or less, have an average equivalent circle diameter of 3 nm or more, the precipitated Ti amount and the total Ti amount in the steel fulfill the relationship represented by formula (1) shown below, and the sum total of the fraction of bainite and the fraction of martensite in the metal microstructure is 80 area % or more. | 01-29-2015 |