Hot rolled high strength steel sheet with excellent formability

Abstract

A hot rolled high strength steel sheet having a satisfactory strength-elongation balance and an stretch frangibility and with excellent formability comprising a steel, which contains: C :0.05 ˜ 0.15% Si :0.5 ˜ 2.0% Mn :0.5 ˜ 2.0% P :0.05% or less S :0.010% or less Al :0.005 ˜ less than 0.10%, and the balance of Fe and inevitable impurities, and in which the metal structure mainly comprises three phases of ferrite, retained austenite and bainite, the amount of the ferrite [V(F)] is 60˜95 area %, the amount of the retained austenite [V(γ)] is 3˜15 vol %, the amount of the bainite [V(B)] in the area ratio is 1.5 times or more of the amount of the retained austenite [V(γ)], and the average hardness of the bainite is 240-400 Hv.

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