US Patent 10590522 Aluminum-iron alloy-coated steel sheet for hot press forming, having excellent hydrogen delayed fracture resistance, peeling resistance, and weldability and hot-formed member using same

An Al—Fe alloy coated steel sheet includes a base steel sheet and an alloy coating layer, wherein the base steel sheet includes, by wt %, C: 0.1%˜0.5%, Si: 0.01%˜2%, Mn: 0.01%˜10%, P: 0.001%˜0.05%, S: 0.0001%˜0.02%, Al: 0.001%˜1.0%, N: 0.001%˜0.02%, and the balance of Fe and other impurities, wherein the alloy coating layer includes: an Al—Fe alloy layer I formed on the base steel sheet and having a Vickers hardness of 200˜800 Hv; an Al—Fe alloy layer III formed on the Al—Fe alloy layer I and having a Vickers hardness of 700˜1200 Hv; and an Al—Fe alloy layer II formed in the Al—Fe alloy layer III continuously or discontinuously in a length direction of the steel sheet, and having a Vickers hardness of 400˜900 Hv, wherein an average oxygen content at a depth of 0.1 μm from a surface of the oxide layer is 20% or less by weight.