High manganese hot dip aluminum-plated steel sheet having excellent sacrificial corrosion resistance and platability and manufacturing method therefor
Provided are a high manganese hot dip aluminum-plated steel sheet and a method for manufacturing the same, the steel sheet including: a base steel comprising, by wt %, 0.3-0.9% of C, 10-25% of Mn, 0.01-0.5% of Ti, 0.01-0.2% of Sn, 0.01-0.1% of Sb, and the balance of Fe and inevitable impurities; a hot dip aluminum-based steel plated layer formed on the base steel sheet and comprising 0.1 wt % or more of a sum of one or more types among Li, Na, and K, and the balance of Al and inevitable impurities; and an Al—Fe—Si—Mn based alloy layer formed between the base steel sheet and the aluminum-based plated layer, and having a dual structure with different average Fe amounts.
1. A high manganese hot dip aluminum-plated steel sheet comprising:
a base steel sheet comprising, by wt %, 0.3 to 0.9% of C, 10 to 25% of Mn, 0.01 to 0.5% of Ti, 0.01 to 0.2% of Sn, 0.01 to 0.1% of Sb, and a balance of Fe and inevitable impurities;
an aluminum-based plated layer formed on the base steel sheet and comprising 0.1 wt % 1.0 wt % or more of a sum of one or more among Li, K, Ca, Na, and Mg, and a balance of Al and inevitable impurities; and
an Al—Fe—Si—Mn-based alloy layer formed between the base steel sheet and the aluminum-based plated layer, and having a dual structure,
wherein the dual structure includes: a lower alloy layer formed on the base steel sheet; and an upper alloy layer formed on the lower alloy layer,
wherein the lower alloy layer has an average Fe content of 50 wt % or more and an average Si content of less than 5 wt %, and
wherein the upper alloy layer has an average Fe content of less than 50 wt % and an average Si content of 5 wt % or more.
2. The high manganese hot dip aluminum-plated steel sheet of claim 1 , wherein the lower alloy layer has an average thickness of 0.2 to 0.8 μm, and the upper alloy layer has an average thickness of 1.5 to 8 μm.
3. The high manganese hot dip aluminum-plated steel sheet of claim 1 , wherein an oxide including one or more of Si, Mn, and Al is discontinuously distributed on an interface of the base steel sheet and the Al—Fe—Si—Mn-based alloy layer, and the oxide has a linear fraction of 0.35 to 0.45, the linear fraction being defined by a value obtained by dividing a length of the oxide projected on the interface in a direction of a cross-section of the steel sheet by a length of the interface.
4. The high manganese hot dip aluminum-plated steel sheet of claim 1 , wherein the aluminum-based plated layer further comprises 0.1 to 13 wt % of Si.