KR910009949A - High tensile cold rolled steel sheet, hot dip galvanized steel sheet and manufacturing method thereof - Google Patents

Abstract

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Description

High tensile cold rolled steel sheet, hot dip galvanized steel sheet and manufacturing method

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Claims (5)

C: 0.03-0.15% by weight, Si: 0.05% by weight or less, Mn: 0.5-1.2% by weight, Nb: 0.005-0.045% by weight and Al: 0.10% by weight or less, the remainder of the structure of iron and unavoidable impurities A high tensile cold rolled steel sheet having excellent stretch flange characteristics, characterized in that the crystalline microcrystalline ferrite structure having an average grain size of 20 µm or less has a structure of 95% or more. C: 0.03-0.15% by weight, Si: 0.05% by weight or less, Mn: 0.5-1.2% by weight, Nb: 0.005-0.045% by weight and Al: 0.10% by weight or less, the remainder of the structure of iron and unavoidable impurities After the steel is hot rolled, cold rolling of 50% or more of reduction ratio is carried out, followed by heating at a heating rate of 5 ° C./s or more in a continuous unwinding line and 20 at a temperature range of 720-780 ° C. -60s A method for producing a high tensile cold rolled steel sheet having excellent stretch flange characteristics, characterized in that it is subjected to annealing to be preserved and then cooled. C: 0.03-0.15% by weight, Si: 0.05% by weight or less, Mn: 0.5-1.2% by weight, Nb: 0.005-0.045% by weight and Al: 0.10% by weight or less, the remainder of the structure of iron and unavoidable impurities A high-strength hot-dip galvanized steel sheet having excellent stretch flange characteristics, characterized in that the microcrystalline recrystallized ferrite structure having an average grain size of 20 μm or less has a structure of 95% or more. C: 0.03-0.15% by weight, Si: 0.05% by weight or less, Mn: 0.5-1.2% by weight, Nb: 0.005-0.045% by weight and Al: 0.10% by weight or less, and the remaining part is contained by iron and unavoidable impurities The material is made of steel, hot-rolled to the material, followed by cold rolling with a rolling reduction of 50% or more, followed by heating at a heating rate of 5 ° C / s in an inline annealing continuous hot dip galvanizing line to a temperature of 720-780 ° C. A high tensile hot dip galvanized steel sheet excellent in stretch flange characteristics, characterized in that it is subjected to 20-60s annealing in the range, then cooled and then plated. C: 0.03-0.15% by weight, Si: 0.05% by weight or less, Mn: 0.5-1.2% by weight, Nb: 0.005-0.045% by weight and Al: 0.10% by weight or less, the remainder being structured in iron and unavoidable impurities Made of steel, which is hot-rolled, and then cold-rolled to 50% or more of reduction ratio, and then heated at a heating rate of 5 ° C / s in an inline annealing continuous hot dip galvanizing line to be 720-780 A method for producing a high tensile strength hot-dip galvanized steel sheet having excellent stretch flange characteristics, characterized in that the annealing is performed at 20 ° C. for 60-60 s in a temperature range of 0 ° C., followed by cooling, followed by plating for subsequent alloying. ※ Note: The disclosure is based on the initial application.