Aluminum-zinc alloy plated steel sheet having excellent hot workability and corrosion resistance, and method for manufacturing same
Provided are an aluminum-zinc alloy plated steel sheet having excellent hot workability and corrosion resistance, and a method for manufacturing same. The plated steel sheet has an Al—Zn hot-dip aluminized coating layer on a base steel sheet, wherein: the coating layer is composed of a lower layer part and an upper layer part; the lower layer part comprises 40-50% of Fe, 50-60% of Al, 1% or less of Si, and other unavoidable impurities, on the basis of wt % of the lower layer part itself; the upper layer part comprises 10-30% of Zn, the balance of Al, and 0.05% or less of at least one of Cr, Mo, and Ni as an impurity, on the basis of wt % of the upper layer part itself; and the thickness of the upper layer part accounts for 30% or less of the total thickness of the coating layer.
1. An Al—Zn alloy plated steel sheet having workability and corrosion resistance, the Al—Zn alloy plated steel sheet comprising an Al—Zn hot-dip aluminized plating layer on a base steel sheet,
wherein the plating layer comprises:
a lower-layer portion comprising, based on a weight thereof:
Fe: 40% to 50%,
Al: 50% to 60%,
Si: 1% or less, and
inevitable impurities; and
an upper-layer portion comprising, based on a weight thereof:
Zn: 10% to 30%,
Al: 69.8 to 90%, and
the balance of 0.05% or less of one or more impurities selected from the group consisting of Cr, Mo, and Ni;
wherein an amount of Si, if present, in the lower-layer portion is the same as or greater than an amount of Si, if present, in the upper-layer portion; and
wherein the upper-layer portion has a thickness which is 30% or less of a total thickness of the plating layer.
2. The Al—Zn alloy plated steel sheet of claim 1 , wherein the base steel sheet is a cold-rolled steel sheet or a hot-rolled steel sheet.
3. The Al—Zn alloy plated steel sheet of claim 1 , wherein the base 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 of Fe and inevitable impurities.
4. The Al—Zn alloy plated steel sheet of claim 1 , wherein the lower-layer portion and the upper-layer portion are free of Si.
5. The Al—Zn alloy plated steel sheet of claim 1 , wherein the amount of Si in the lower-layer portion is the same as the amount of Si in the upper-layer portion.
6. The Al—Zn alloy plated steel sheet of claim 1 , wherein the amount of Si in the lower-layer portion is greater than the amount of Si in the upper-layer portion.