COLD ROLLED STEEL SHEET AND HOT-DIP ZINC PLATED STEEL SHEET WITH SUPERIOR PRESS FORMABILITY AND BAKE HARDENABILITY AND METHOD FOR MANUFACTURING THE STEEL SHEETS

摘要

PURPOSE: A cold-rolled steel sheet and a hot-dip zinc plated steel sheet with excellent press formability and bake hardenability and a manufacturing method thereof are provided to improve tensile strength by controlling the formation of a deposited material. CONSTITUTION: A cold-rolled steel sheet with bake hardenability is composed of C 0.001~0.004 weight%, Mn 0.1~0.2 weight%, Si 0.05~0.250.05~0.25 weight%, S 0.003~0.025 weight%, Al 0.01~0.15 weight%, N less than 0.005 weight%, P 0.01~0.10 weight%, Cu 0.01~0.2 weight%, B 0.0001~0.003 weight%, Fe and inevitable. The cold-rolled steel sheet comprises a deposited material. 50% or more of the deposited material is AIN and BN deposited materials. The average diameter of the AIN and BN deposited materials is 30~100nm.