HIGH-STRENGTH PLATED STEEL SHEET HAVING EXCELLENT PLATING PROPERTIES, WORKABILITY, AND DELAYED FRACTURE RESISTANCE, AND METHOD FOR PRODUCING SAME

摘要

Provided are a hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel sheet having at least 980 MPa, having excellent plating properties, workability in terms of bendability and hole expandability, and delayed fracture resistance, and also having excellent shock absorption resistance. This high-strength plated steel sheet is a plated steel sheet having a plating layer on the surface of a base material steel sheet, includes predetermined steel components, and comprises, in order from the interface between the base material steel sheet and the plating layer toward the base material steel sheet side: a soft layer having a Vickers hardness that is 90% or less of the Vickers hardness at a t/4 position of the base material steel sheet, where t is the thickness of the base material steel sheet; and a hard layer constituted by a structure mainly including martensite and bainite, and in which the average grain size of prior austenite is 20 µm or less. The average depth D of the soft layer is 20 µm or greater, and the average depth d of an inner oxide layer is 4 µm or greater and less than D.