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|1. (WO2017038070) HIGH STRENGTH THIN STEEL SHEET AND METHOD FOR MANUFACTURING SAME|
|Applicants:||JFE STEEL CORPORATION
|Title:||HIGH STRENGTH THIN STEEL SHEET AND METHOD FOR MANUFACTURING SAME|
Provided is a high strength thin steel sheet having both excellent tensile strength and elongation, and also having low elongation anisotropy. This high strength thin steel sheet has a predetermined composition, and has a structure in which the total area ratio of ferrite, tempered bainitic ferrite and bainitic ferrite is 40-70%, the area ratio of martensite is 5-30%, the area ratio of retained austenite 10-35%, the average equivalent circular diameter of martensite and retained austenite (second phase) grains is 2.0 µm or less, the area ratio of grains having an equivalent circular diameter of 2.0 µm or greater in the second phase is 10% or less, and the average short diameter of grains in the second phase is 0.40 µm or less.