CONTINUOUS HOT-DIP GALVANIZED STEEL SHEET FOR OUTER PANEL WITH EXCELLENT PRESS-FORMABILITY AND METHOD OF MANUFACTURING THE SAME

摘要

PURPOSE: A continuous hot-dip galvanized steel sheet with superior press-formablity for an outer panel and a manufacturing method thereof are provided to minimize zeta-alloy phase by securing the optimum cooling speed of cooling equipment after galvannealing and cracking. CONSTITUTION: A method for manufacturing a continuous hot-dip galvanized steel sheet with superior press-formablity for an outer panel is as follows. A cold rolled steel sheet, which comprises C(Carbon) of 0.005wt.% or less, Si(Silicon) of 0.015wt.% or less, Mn(Manganese) of 0.15wt.% or less, P(Phosphorus) of 0.010-0.020wt.%, Al(Aluminum) of 0.02-0.06wt.%, Ti(Titanium) of 0.020-0.035wt.%, Nb(Niobium) of 0.010-0.020wt.%, N(Nitrogen) of 0.005wt.% or less, and Fe(Iron) and inevitable impurities of the remaining amount, is galvanized. The galvanized cold rolled steel sheet is induction-heated through an induction-heating unit(160). The heated steel sheet is rapidly cooled from 500C to 460C and air-cooled from 460C.