HIGH-STRENGTH THIN STEEL SHEET AND PROCESS FOR MANUFACTURING SAME

摘要

According to the present invention, a high-strength thin steel sheet which has a high tensile strength (TS) of 980MPa or higher and which stably exhibits excellent bendability over the whole of the sheet can be obtained. This high-strength thin steel sheet has a prescribed steel composition and a structure wherein: the average ferrite grain diameter is 10mum or less; the volume fraction of ferrite is 30 to 70%; the total volume fraction of martensite and retained austenite is 10% or less; and the ratio of pairs of adjacent phases such that the nano-hardness difference between the adjacent phases of each pair is 4GPa or smaller is 90% or more.