HIGH YIELD RATIO AND HIGH STRENGTH COLD ROLLED STEEL SHEET, GALVANIZED STEEL SHEET AND MANUFACTURING METHOD THEREOF

摘要

A high yield ratio high-strength cold-rolled steel sheet with a superior solderability, a molten galvanizing steel plate and a manufacturing method thereof are provided to reduce the manufacturing cost in the alloy steel slab manufacturing. A manufacturing method for the high yield ratio high-strength cold-rolled steel sheet with a superior solderability comprises: a step of heating a steel slab to the 1180~1220°C; a step of hot finishing rolling the steel slab at 900~940°C; a step of cool winding within 540~580°C; a step of cool rolling with the reduction rate more than 45%; a step of annealing within 780~830°C; a step of performing a melting zinc plating process; and a step of temper rolling with the reduction rate 0.4~1.1%.