STEEL USED AS HIGH STRENGTH HOT DIP COATED STEEL SHEET HAVING SUPERIOR YIELD STRENGTH AND SURFACE PROPERTIES AND MANUFACTURING METHOD THEREOF

摘要

A steel sheet for the high intensity melting zinc coating with a superior surface quality the deviation of resistant strength is less and manufacturing method thereof are provided. A manufacturing method of the steel sheet for the high intensity melting zinc coating performs the followings: a step for heating to 1150~1190‹C the steel slab; a step for heat with finishing rolling in 880~920‹C; a step for performing the coiling in the temperature range of 520~540‹C; and a step for manufacturing the cold rolled steel sheet at the reduction rate more than 70%. The cold rolled steel sheet consecutively is annealed at the temperature range of 750~810‹C and roll to the reduction rate of 1.6~2.0%.