Patent application number | Description | Published |
20130017411 | HOT-DIP GALVANIZED STEEL SHEET AND ALLOYED HOT-DIP GALVANIZED STEEL SHEET, EACH HAVING EXCELLENT WORKABILITY, HIGH YIELD RATIO AND HIGH STRENGTHAANM Hamada; KazuyukiAACI Kakogawa-shiAACO JPAAGP Hamada; Kazuyuki Kakogawa-shi JPAANM Asai; TatsuyaAACI Kakogawa-shiAACO JPAAGP Asai; Tatsuya Kakogawa-shi JP - Disclosed is a hot-dip galvanized steel sheet or an alloyed hot-dip galvanized steel sheet, which has a tensile strength of 980 MPa or more, excellent workability, high yield ratio and high strength. The hot-dip galvanized steel sheet or the alloyed hot-dip galvanized steel sheet is characterized by containing 0.12-0.3% by mass of C, 0.1% by mass or less (excluding 0% by mass) of Si, 2.0-3.5% by mass of Mn, 0.05% by mass or less (excluding 0% by mass) of P, 0.05% by mass or less (excluding 0% by mass) of S, 0.005-0.1% by mass of Al and 0.015% by mass or less (excluding 0% by mass) of N, with the balance made up of iron and unavoidable impurities. The hot-dip galvanized steel sheet or the alloyed hot-dip galvanized steel sheet is also characterized in that the metallic structure thereof contains bainite as a matrix structure, and the area ratio of ferrite is 3-20% and the area ratio of martensite is 10-35% relative to the entire structure. | 01-17-2013 |
20130153096 | HIGH-YIELD-RATIO AND HIGH-STRENGTH STEEL SHEET EXCELLENT IN WORKABILITY - Provided is a steel sheet having a tensile strength of 980 MPa or more and exhibiting a high yield ratio and an excellent workability. The steel sheet includes C, Si, Mn, B, at least one of Ti, Nb and V, P, S, Al and N, the content by percentage of each of which is in a specified range. The metal structure thereof includes bainite, and martensite and may include ferrite. The proportion by area of bainite in the entire metal structure is 42 to 85%, that of martensite is 15 to 50%, that of ferrite is 5% or less, and that of entire microstructure of the balance other than bainite, martensite and ferrite is 3% or less thereof. Furthermore, bainite has an average crystal grain diameter of 7 μm or less. | 06-20-2013 |
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 |
20130263637 | PRESS FORMING METHOD FOR STEEL PLATE - A press forming method forming an extended part by extension in a later forming period after deep drawing, the deep drawing process carried out with working at 100-250° C., and the extension forming process carried out colder at less than 50° C., whereby the extended part is formed by extension in a cup shaped low parts formed by deep drawing. Thus, press forming products containing formed elements can be deep drawing formed and extension formed at a high forming rate of 10 mm/sec or greater, which can assure high productivity. By making a steel plate temperature 100-350° C. during press forming and by making the forming rate in the later forming period where extension forming is carried out slower than the forming rate in an earlier forming period where extension forming is not carried out, cracking of the extended part can be prevented and press forming limitations can be improved. | 10-10-2013 |
20130273391 | HIGH-YIELD-RATIO HIGH-STRENGTH STEEL SHEET HAVING EXCELLENT WORKABILITY - A steel sheet according to the present invention has tensile strength of 980 MPa or more, exerts a high-yield ratio, and has excellent workability (in detail, strength-ductility balance). The steel sheet contains: C: 0.06-0.12% (excluding 0.12%); Si: 0.2% or less; Mn: 2.0-3.5%; at least one element selected from the group consisting of Ti, Nb, and V of 0.01-0.15% in total; B: 0.0003-0.005%; P: 0.05% or less; S: 0.05% or less; Al: 0.005-0.1%; N: 0.015% or less; and the balance is iron and unavoidable impurities, in which the content of ferrite is more than 5% to 15% or less, that of martensite is 25-55%, and the total content of bainite and tempered martensite is 30% or more to less than 70%, based on the whole microstructure, and in which the average crystal grain size of the ferrite is 3.0 μm or less. | 10-17-2013 |
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 |
20140144560 | METHOD OF MANUFACTURING HOT-PRESS-FORMED STEEL MEMBER - To establish a method for obtaining a hot-press-formed steel member, which exhibits high strength, high tensile elongation (ductility) and high bendability, thereby having excellent deformation characteristics at the time of collision crush (crashworthiness), and which is capable of ensuring excellent delayed fracture resistance. A method for producing a hot-press-formed steel member by heating a steel sheet, which has a chemical component composition containing 0.10% (% by mass, and hereinafter the same shall apply) to 0.30% (inclusive) of C, 1.0% to 2.5% (inclusive) of Si, 1.0% to 3.0% (inclusive) of Si and Al in total and 1.5% to 3.0% (inclusive) of Mn, with the balance consisting of iron and unavoidable impurities, and hot press forming the steel sheet one or more times. The method for producing a hot-press-formed steel member is characterized in that: the heating temperature is set to not less than the Ac3 transformation point; the starting temperature of the hot pressing is set to not more than the heating temperature but not less than the Ms point; and the average cooling rate from (the Ms point−150° C. to 40° C. is set to 5° C./s or less. | 05-29-2014 |
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 |
20150024234 | METHOD FOR MANUFACTURING HOT-PRESS FORMED STEEL-MEMBER, AND THE HOT-PRESS FORMED STEEL-MEMBER - There is provided a method for manufacturing a hot-press formed steel-member, the method being capable of reducing LME without causing cracking of a galvanized steel sheet. The method includes a step of using a galvanized steel sheet, a base steel thereof, having a prescribed chemical composition, a heating step of heating the galvanized steel sheet to not lower than an Ac | 01-22-2015 |
20150044502 | HOT-DIP GALVANIZED STEEL SHEET FOR STAMPING HAVING EXCELLENT COLD WORKABILITY, DIE HARDENABILITY, AND SURFACE QUALITY, AND PRODUCING METHOD THEREOF - Disclosed is a hot-dip galvanized steel sheet for stamping, which has excellent cold workability, has such satisfactory surface quality as to be free from unplating and other defects even in the absence of dedicated facilities, and ensures a strength of 1370 MPa or more after quenching even when cooled at a low rate. Also disclosed is a method effective for the produce of the hot-dip galvanized steel sheet for stamping. The hot-dip galvanized steel sheet for stamping comprises a base steel sheet and a hot-dip galvanized layer on a surface of the base steel sheet, in which the base steel sheet has a predetermined chemical composition and has a microstructure comprising equiaxed ferrite having an average aspect ratio of 4.0 or less and cementite and/or pearlite having an average major axis of grains of 20 μm or less. | 02-12-2015 |