HIGH-STRENGTH STEEL SHEET WITH EXCELLENT DUCTILITY AND CRACKLESS EDGE PORTION, HOT-DIP GALVANIZED STEEL SHEET, AND MANUFACTURING METHOD THEREOF

摘要

An object of the present invention is to provide a steel sheet with a tensile strength of 780 to 980 MPa and an elongation of 28% or higher, and a crackless edge portion. The present invention provides a high-strength steel sheet, a hot-dip galvanized steel sheet and a method for manufacturing these steel sheets, the steel sheet comprising: by weight %, C: 0.1 to 0.25%, Si: 1.0 to 1.9%, Mn: 1.5 to 2.5%, Al: 0.5 to 1.6%, Ti: 0.005 to 0.03%, B: 5 to 30 ppm, and Sb: 0.01 to 0.03%, and the remainder consisting of Fe and inevitable impurities, wherein 1.75=Si+Al=3.25.