▎ 摘　　要

NOVELTY - A high-strength steel plate comprises a base steel plate, and a ferrite layer formed on a surface layer of the base steel sheet. The ferrite layer has an internal oxide layer on which an iron-nickel alloy layer is formed. The inner oxide layer is formed from surface of the ferrite layer to a maximum depth of 3 μ m in the thickness direction along grain boundary of base structure of the base steel sheet. The iron-nickel alloy layer has excellent surface quality formed in the internal oxide layer from the surface of ferrite layer to a depth of 2 μ m or more in the thickness direction along the grain boundary of matrix structure of the base steel sheet. USE - High-strength steel plate. ADVANTAGE - The high-strength steel plate has excellent surface quality and plating properties, and suppresses liquid metal embrittlement phenomenon of transformation induced plasticity steel and minimizes formation of oxides near the steel surface. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for manufacture of the high-strength steel sheet.