High-strength elongation steel sheet, method for manufacturing hot-rolled steel sheet, cold-rolled steel sheet, zinc-coated steel sheet, and alloyed zinc-coated steel sheet

Abstract

The present invention relates to a steel sheet which is used as structural members of vehicles, and a manufacturing method thereof. The invention provides a method for manufacturing high-strength elongation steel sheets, hot-rolled steel sheets, cold-rolled steel sheets, zinc-coated steel sheets, and alloyed zinc-coated steel sheet. The steel sheet comprises C: 0.5~1.0%, Mn: 0.01~2.0%, Si: 1.0~2.0%, Al: 0.01~2.0%, S: less than 0.012%, Fe: the remaining %, and other inevitable impurities based on weight percent. The inner structure of the steel sheet comprises bainite and remaining austenite. The steel sheet has an average lath width of the bainite: less than 0.3?, yield strength: more than 700MPa, tensile strength: more than 980MPa, and elongation: more than 20%. The present invention contributes to the weight reduction of the steel sheet for vehicles and crash safety by providing the steel sheet with a yield strength of more than 700MPa, tensile strength of more than 980MPa, elongation of more than 20%, hot-rolled steel sheet, cold-rolled steel sheet, zinc-coated steel sheet, and alloyed zinc-coated steel sheet.

Description

technical field [0001] The present invention relates to a steel plate usable for structural members and inner panels of vehicles and a method for producing the same, and more particularly, to a steel plate having high strength and elongation and the production of hot-rolled steel plates and cold-rolled steel plates having high strength and elongation , The method of electro-galvanized steel sheet and hot-dip galvanized steel sheet. Background technique [0002] Recently, the emission of carbon dioxide has been restricted in order to protect the environment, and the demand for improvement of fuel efficiency of vehicles has gradually become higher. In addition, in order to ensure the safety of passengers when vehicles collide with each other, it is also required to improve the safety mainly in vehicle body collision characteristics. Therefore, it is required to improve the workability of a high-strength steel sheet as a means to realize weight reduction and safety of a vehicl...

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Problems solved by technology

However, there is a disadvantage that the phase transition time of the method is so long that the method cannot be used in hot rolling or annealing processes

[0007] In addition, although Korean Patent No. 2007-0126202 proposes a steel material with a specified composition through austenitic transformation treatment followed by constant temperature transformation at a temperature between Bs temperature and Bs-100°C to obtain a The method of steel with above tensile strength and elongation above 10%, but the disadvantage is that because expensive alloy elements such as Cr, Ni, Mo need to be added, the manufacturing cost is high, and the method is limited to thermal rolled steel

[0008] Although Sandvik et al. proposed in Metals Technology (p213-220, 1981) to add 0.65-0.99 wt% C, 2-2.78 wt% Si, 0.5 wt% Mn, 0.02-0.79 wt% Cr and 0-0.03 wt% %Ti steel is subjected to austenitic heat treatment followed by heat treatment in the range of 290°C to 380°C to obtain ultra-high strength steel, but the disadvantage is that the high content of Si in the steel makes the rollability so poor that it is difficult to The method is applied to hot rolling and cold rolling and the method is limited to hot rolled steel sheets

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