Thin steel sheet and plated steel sheet, manufacturing method of hot rolled steel sheet, manufacturing method of cold rolled full hard steel sheet, method of manufacturing heat treatment plate, method of manufacturing thin steel sheet and method of manufacturing plated steel sheet

摘要

A thin steel sheet having a TS of 540 MPa or more, excellent in ductility, low yield ratio (YR), excellent in-plane anisotropy of YP and excellent plating property. Wherein the ferrite includes a specific component composition, ferrite and a second phase, the ferrite has an area ratio of 50% or more, the second phase has an area ratio of 1.0% or more and 25.0% Martensite, the average crystal grain size of the ferrite is 3 m or more, the hardness difference between the ferrite and the martensite is 1.0 GPa or more and 8.0 GPa or less, and the texture of the ferrite is And a steel structure having an inverse strength ratio of -fiber to -fiber of 0.8 or more and 7.0 or less, and has a tensile strength of 540 MPa or more.