Patent application number | Description | Published |
20080226491 | AUTOMOBILE HIGH-STRENGTH ELECTRIC RESISTANCE WELDED STEEL PIPE WITH EXCELLENT LOW-TEMPERATURE IMPACT PROPERTIES AND METHOD OF MANUFACTURING THE SAME - Disclosed is a high-strength electric resistance welded steel pipe which is manufacture from a steel sheet containing, on mass basis, 0.2% to 0.4% C, 0.05% to 0.5% Si, 0.5% to 2.5% Mn, 0.025% or less P, 0.01% or less S, 0.01% to 0.15% or Al, 0.01% to 2% Cu, 0.05% to 2% Cr, 0.005% to 0.2% Ti, and 0.0002% to 0.005% B, with the remainder being iron and inevitable impurities. The steel pipe has a tensile strength of 1750 N/mm | 09-18-2008 |
20100132848 | ULTRAHIGH-STRENGTH STEEL SHEET EXCELLENT IN HYDROGEN EMBRITTLEMENT RESISTANCE AND WORKABILITY, AND MANUFACTURING METHOD THEREFOR - The ultrahigh-strength steel sheet contains, in mass %, C: 0.05-0.25%, Si: 1.00-2.5%, Mn: 2.0-4.0%, P: 0.1% or below (not inclusive of 0%), S: 0.05% or below (not inclusive of 0%), Al: 0.01-0.15%, Ti: 0.003-0.10%, N: 0.01% or below (not inclusive of 0%), the balance comprising iron with inevitable impurities, and is a composite structure steel sheet comprising 10-50 area % ferrite and 50 area % or above martensite, in which the average circle-equivalent grain diameter of ferrite grains is 2.0 μm or below, the average aspect ratio of ferrite grains is 2.0 or below, and the tensile strength is 1,100 MPa or above. Accordingly, the ultrahigh-strength steel sheet is excellent in hydrogen embrittlement resistance and workability. | 06-03-2010 |
20100247957 | HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLENT IN BENDING WORKABILITY - Disclosed is a cold-rolled steel sheet having a specific steel composition and having a composite steel structure including a ferrite structure and a martensite-containing second phase. In a surface region of the steel sheet from the surface to a depth one-tenth the gage, the number density of n-ary groups of inclusions determined by specific n-th determinations is 120 or less per 100 cm | 09-30-2010 |
20110287280 | HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLENT IN BENDING WORKABILITY - A cold-rolled steel sheet has a chemical composition of C: 0.12% to 0.3%, Si: 0.5% or less, Mn: less than 1.5%, Al: 0.15% or less, N: 0.01% or less, P: 0.02% or less, and S: 0.01% or less, with the remainder including iron and inevitable impurities and has a martensite single-phase structure as its steel microstructure. In a surface region of the steel sheet from the surface to a depth one-tenth the gauge, the number density of n-ary groups of inclusions determined by specific n-th determinations is 120 or less per 100 cm | 11-24-2011 |
20120312433 | HIGH-STRENGTH STEEL SHEET EXCELLENT IN WORKABILITY AND COLD BRITTLENESS RESISTANCE, AND MANUFACTURING METHOD THEREOF - The invention relates to a steel sheet having a tensile strength of 1180 MPa or more, which excels in workability and cold brittleness resistance. The high-strength steel sheet contains 0.10% to 0.30% of C, 1.40% to 3.0% of Si, 0.5% to 3.0% of Mn, 0.1% or less of P, 0.05% or less of S, 0.005% to 0.20% of Al, 0.01% or less of N, 0.01% or less of O, as well as Fe and inevitable impurities. The steel sheet has: (i) a ferrite volume fraction of 5% to 35% and a bainitic ferrite and/or tempered martensite volume fraction of 60% or more; (ii) a MA constituent volume fraction of 6% or less (excluding 0%); and (iii) a retained austenite volume fraction of 5% or more. | 12-13-2012 |
20130008570 | ULTRAHIGH-STRENGTH STEEL SHEET WITH EXCELLENT WORKABILITY, AND MANUFACTURING METHOD THEREOF - Disclosed is an ultra high strength steel plate with at least 1100 MPa of tensile strength that has both an excellent strength-stretch balance and excellent bending workability, and a method for producing the same. The metal structure of the steel plate has martensite, and the soft phases of bainitic ferrite and polygonal ferrite. The area of the aforementioned martensite constitutes 50% or more, the area of the aforementioned bainitic ferrite constitutes 15% or more, and the area of the aforementioned polygonal ferrite constitutes 5% or less (including 0%). When the circle-equivalent diameter of the aforementioned soft phases is measured, the coefficient of variation (standard deviation/mean value) is less or equal to 1.0. The ultra high strength steel plate has at least 1100 MPa of tensile strength. | 01-10-2013 |
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 |
20130040165 | HIGH-STRENGTH STEEL SHEET EXCELLENT IN SEAM WELDABILITY - Disclosed is a high-strength steel sheet having a tensile strength of 1180 MPa or more and having satisfactory seam weldability. The steel sheet has a chemical composition of C: 0.12% to 0.40%, Si: 0.003% to 0.5%, Mn 0.01% to 1.5%, Al: 0.032% to 0.15%, N: 0.01% or less, P: 0.02% or less, S: 0.01% or less, Ti: 0.01% to 0.2% or less, and B: 0.0001% to 0.01%, with the remainder including iron and inevitable impurities, has a Ceq1 (=C+Mn/5+Si/13) of 0.50% or less, and has a steel structure of a martensite single-phase structure. | 02-14-2013 |
20150086808 | HIGH-STRENGTH COLD-ROLLED STEEL SHEET, HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET, AND HIGH-STRENGTH HOT-DIP GALVANNEALED STEEL SHEET EXCELLENT IN FORMABILITY AND SHAPE FIXABILITY, AND METHODS FOR MANUFACTURING THEM - A high-strength cold-rolled steel sheet has a specific chemical composition and has a steel microstructure meeting conditions: a total content of bainitic ferrite (BF) and tempered martensite (TM) is 65% (in area percent, hereinafter the same for steel microstructure) or more; a fresh martensite (M) content is 3% to 18%; a retained austenite content is 5% or more; and a polygonal ferrite (F) content is 5% or less. The steel sheet has a specific average KAM | 03-26-2015 |