Patent application number | Description | Published |
20100108200 | HIGH YIELD RATIO AND HIGH-STRENGTH HOT-DIP GALVANIZED STEEL SHEET EXCELLENT IN WORKABILITY AND PRODUCTION METHOD THEREOF - A high-strength hot-dip galvanized steel sheet excellent in workability according to the present invention: contains C, Si, Mn and other elements; has a dual phase structure containing ferrite and martensite as the metallographic structure; and, in the ferrite structure, satisfies the expression 0.2≦(L | 05-06-2010 |
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 |
20100247958 | HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLENT IN WORKABILITY AND SHAPE FREEZING PROPERTY - A high-strength cold-rolled steel sheet according to the present invention: satisfies the requirement of a prescribed chemical composition; has a structure comprising a mother phase structure of ferrite and a second phase structure of retained austenite and martensite (the martensite may not be included); and satisfies the following expressions (1) and (2) when the volume fraction of the ferrite in the whole structure is represented by Vf (%), the volume fraction of the retained austenite in the whole structure is represented by Vγ (%), the carbon content in the retained austenite is represented by Cγ (mass %), the shortest distance between the second phase structures is represented by dis (μm), and the average grain size of the second phase structures is represented by dia (μm), | 09-30-2010 |
20110318605 | HIGH STRENGTH STEEL SHEET HAVING EXCELLENT FORMABILITY - A high strength steel sheet contains, in percent by mass, 0.03 to 0.2% of C, 0.5 to 2.5% of Si, 1 to 3.0% of Mn, 0.01 to 0.5% of Cr, 0.01 to 0.5% of Mo, 0.02 to 0.15% of Al, 0.15% or less of Ti, 0.15% or less of No, and 0.15% or less of V; wherein the remainder includes Fe and inevitable impurities, and the content of Si satisfies the following formula (1), | 12-29-2011 |
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 |
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 |
Patent application number | Description | Published |
20090025831 | HOT-DIP GALVANIZED STEEL SHEET AND GALVANNEALED STEEL SHEET - Disclosed is a hot-dip galvanized steel sheet, in which a steel sheet of the hot-dip galvanized steel sheet before galvanization contains, on the percent by mass basis, 0.06% to 0.15% carbon (C); 1% to 3% manganese (Mn); 0.01% to 0.05% phosphorus (P); 0.03% to 1% chromium (Cr); 0.03% to 1% molybdenum (Mo); and 0.02% to 0.15% aluminum (Al). The steel sheet before galvanization has a silicon (Si) content of 0.2% or less (inclusive of 0%) and a sulfur (S) content of 0.03% or less (inclusive of 0%) and has a K value of −2.0 or more, in which the K value is calculated according to following Equation (1): | 01-29-2009 |
20090053096 | HIGH-STRENGTH COLD-ROLLED STEEL SHEET EXCELLENT IN COATING ADHESION, WORKABILITY AND HYDROGEN EMBRITTLEMENT RESISTANCE, AND STEEL COMPONENT FOR AUTOMOBILE - A cold rolled steel sheet satisfying on the basis of percent by mass the chemical composition of 0.06-0.6% C, 0.1-2% Si, 0.01-3% Al, 1-4% Si+Al, 1-6% Mn, Si/Mn≦0.40, in which there exists 10 or more pieces/100 μm | 02-26-2009 |
20090056836 | HIGH-STRENGTH STEEL SHEET HAVING EXCELLENT WORKABILITY - According to the present invention, there is provided a high strength steel sheet, which has, for example, a tensile strength of 590 to 980 MPa or more, which has favorable workability, and which is useful for an automobile, etc. The high strength steel sheet of the present invention comprises 0.03 to 0.20% C (% by mass in chemical compositions; hereafter, the same holds true), 0.50 to 2.5% Si, 0.50 to 2.5% Mn, and further, preferably 0.02 to 0.2% Mo. Moreover, its metal structure includes ferrite and low temperature transformation phase. The mean grain size of the low temperature transformation phase is 3.0 μm or less. Further, grains whose size is 3.0 μm or less occupy 50% or more by area ratio of the low temperature transformation phase, and an average aspect ratio of the low temperature transformation phase is 0.35 or more. | 03-05-2009 |
20090277547 | HIGH-STRENGTH STEEL SHEETS AND PROCESSES FOR PRODUCTION OF THE SAME - A high strength steel sheet with both excellent elongation and stretch-flanging performance is provided. | 11-12-2009 |
20100003541 | HIGH-STRENGTH HOT DIP GALVANNEALED STEEL SHEET HAVING HIGH POWDERING RESISTANCE AND METHOD FOR PRODUCING THE SAME - Disclosed is a high-strength hot dip galvannealed steel sheet having high powdering resistance produced by employing such a constitution that a Fe—Zn alloy plated layer is provided on at least one side of a basis steel sheet and a region in which Al (atomic %)/Zn (atomic %)≧0.10 is present in a thickness of 300 Å or more from the surface of the plated layer along the depth direction of the plated layer. Also disclosed is a hot dip galvannealed steel sheet whose formability is greatly improved by optionally specifying chemical composition and structure of the basis steel sheet. | 01-07-2010 |