Aluminum-zinc alloy plated steel sheet having excellent hot workability and corrosion resistance, and method for manufacturing same
The present disclosure relates to a manufacture for manufacturing an Al—Zn alloy plated steel sheet having high hot workability and corrosion resistance.
1 . A method for manufacturing an Al—Zn alloy plated steel sheet, the method comprising:
immersing and discharging a steel sheet in and from a plating bath which comprises, by wt %, Zn: 10% to 30%, Si: 1% or less, and a balance of Al and inevitable impurities;
air wiping the steel sheet within a temperature range of 200° C. to 300° C. to adjust a thickness of a plating layer of the steel sheet discharged from the plating bath; and
forming an alloy plating y alloying the thickness-adjusted plating layer of the steel sheet within a temperature range of 500° C. to 670° C.
2 . The method of claim 1 , wherein the alloy plating layer comprises a lower-layer portion and an upper-layer portion; the lower-layer portion comprises, based on a weight thereof, Fe: 40% to 50%, Al: 50% to 60%, Si: 1% or less, and other inevitable impurities; the upper-layer portion comprises, based on a weight thereof, Zn: 10% to 30%, and the balance of Al and 0.05% or less of one or more other impurities selected from the group consisting of Cr, Mo, and Ni; and the upper-layer portion has a thickness which is 30% or less of a total thickness of the alloy plating layer.
3 . The method of claim 1 , wherein the thickness-adjusted plating layer is alloyed within a temperature range of 630° C. to 670° C.
4 . The method of claim 1 , wherein the steel sheet comprises, by wt %, C: 0.05% to 0.3%, Si: 0.01% to 2.5%, Mn: 0.5% to 8%, Al: 0.01% to 0.5%, B: 100 ppm or less, and the balance Fe and inevitable impurities.
5 . The method of claim 4 , wherein the steel sheet is a cold rolled steel sheet or a hot rolled steel sheet.