ULTRA HIGH-STRENGTH HOT- DIP GALVANIZED STEEL SHEET HAVING EXCELLENT FORMABILITY AND GALVANIZING PROPERTY, AND METHOD FOR PRODUCING THE SAME

摘要

PURPOSE: An ultra high-strength hot-dip galvanized steel sheet and a method for producing the same are provided to obtain a hot-dip galvanized steel sheet having excellent elongation ratio. CONSTITUTION: A method for manufacturing an ultra high-strength hot-dip galvanized steel sheet is as follows. Steel is subject to equalizing at 1200°C or higher and then hot rolling at 850~950. The treated steel is wound at 500~700°C. The cooled steel is subjected to cold rolling at a cold-rolling ratio of 50%, annealing, hot-dip galvanizing, and then alloying hot-dip galvanizing.